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401
|
Type determination for SN 2005L
|
The Nearby Supernova Factory: G. Aldering, B. C. Lee, S. Loken, P. Nugent, S. Perlmutter, J. Siegrist, R. Scalzo, R. C. Thomas, L. Wang (Lawrence Berkeley National Laboratory, Berkeley, CA), G. Adam, R. Bacon, C. Bonnaud, L. Capoani, D. Dubet, F. Henault, B. Lantz, J-P. Lemonnier, A. Pecontal, E. Pecontal (Centre de Recherche Astronomique de Lyon), N. Blanc, G. Boudoul, S. Bongard, A. Castera, Y. Copin, E. Gangler, L. Sauge, G. Smadja (Institut de Physique Nucleaire de Lyon), R. Kessler (Kavli Institute for Cosmological Physics, Chicago, IL), P. Antilogus, P. Astier, E. Barrelet, G. Garavini, S. Gilles, L-A. Guevara, D. Imbault, C. Juramy, R. Pain, R. Taillet, D. Vincent (Laboratoire de Physique Nucleaire et de Haute Energies de Paris), C. Baltay, D. Rabinowitz, A. Bauer (Yale)
|
A spectrum (range 330-990 nm) of SN 2005L in MCG+07-33-5 (IAUC # 8469 ), obtained Jan 27.64 UT with the SuperNova Integral Field Spectrograph on the University of Hawaii 2.2m telescope, reveals it to be a very peculiar type Ia supernova possibly one to two weeks past maximum. Assuming a host redshift from the Sloan Digital Sky Survey of z = 0.07, we clearly identify the Si II 6150 AA absorption at ejection velocity 10,000 km/s. The blue region (330-510 nm) is littered with numerous absorption features from intermediate mass elements, among which we identify Mg II, Si III and a weak Ca II.
|
2005-01-28 06:54:00
|
optical,supernovae
|
402
|
Optical observations of the X-ray Transient XTE J1118+480
|
C. Zurita (IAC), P. RodrÃguez-Gil (IAC), J. Casares (IAC), T. Muñoz-Darias (IAC), M. A. P. Torres (CfA), T. Shahbaz (IAC)
|
Time resolved (40-sec resolution, ~6-hours per night), R-band photometry of the outbursting black hole candidate XTE J1118+480 (ATEL #383) was obtained with the European Space Agency, 1-m OGS telescope at the Spanish Observatorio del Teide (Tenerife) from 2005 Jan 21.01 to Jan 26.30. The average R-band magnitude displays a linear decay with a rate of ~0.06 mag/day. Mean magnitudes are: Jan 21.3, 13.54+-0.01; Jan 22.07, 13.61+-0.01; Jan 23.14, 13.65+-0.01; Jan 24.15, 13.70+-0.01; Jan 25.15, 13.77+-0.01; Jan 26.12, 13.84+-0.01. On Jan 20 and Jan 22, we found a 0.02-mag amplitude modulation consistent with the 0.170-day superhump period observed during the 2000 outburst (IAUC # 7394 , # 7407 ), and with the periodic humps reported in 2005 (ATEL #399). However, no orbital variation was apparent in the remaining nights, although substantial scatter was present.
|
2005-01-29 02:36:00
|
optical,x-ray,binary,black hole,transient
|
403
|
ROTSE-III detection of optical outburst of 2QZ J142701.6-012310
|
E. Rykoff (UMich) on behalf of the ROTSE collaboration
|
Online analysis of ROTSE-III sky patrol fields for new transients has revealed an outburst of 2QZ J142701.6-012310. The object was detected at m_R=15.1 on 23 January 2005, and was dimmer than m_R=18.0 on 21 January. This object had been labeled as a potential blazar by the 2dF survey, although the survey had not been able to assign a redshift to the object. The quiescent counterpart is visible in SDSS and is pointlike and very blue with m_R=20.4. We have taken a spectrum with the HET on 25 January, which shows no obvious absorption or emission features. At this time, we are unable to determine whether this is a blazar or galactic CV. Further information including finding charts, spectra and a light curve can be found at the link provided.
|
2005-01-29 06:48:00
|
optical,agn,blazar,cataclysmic variable,transient,variables
|
404
|
Recent VLA radio observations of XTE J1118+480
|
M. P. Rupen (NRAO/GSFC), V. Dhawan, A. J. Mioduszewski (NRAO)
|
We report further Very Large Array (VLA) observations of the continuing outburst of the black hole candidate binary XTE J1118+480 (e.g., ATEL #399, ATEL #400, ATEL #402). Our most recent observation (31 January 2005, MJD 53401.306) showed a 1.4+/-0.1 mJy source at 8.46 GHz. Multi-frequency observations taken on MJD 53399 show a rising (nu^0.3) spectrum between 4.86 and 8.46 GHz, as is also seen from 4.86 to 22.46 GHz on MJD 53396. Our data show the radio emission has decayed roughly exponentially with a time constant of 10 days since the original radio detection on MJD 53383, a decay punctuated by a few-mJy radio flare sometime between our observations on MJD 53386 and MJD 53391. A plot of the current radio light curve is available at
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
|
2005-02-03 05:32:00
|
radio,x-ray,binary,black hole,transient
|
405
|
Binary period in Optical counterpart to XMMU J004723.7-731226 (SXP 264)
|
W. R.T. Edge, M. J. Coe and J. L. Galache (Southampton University)
|
A probable binary period has been detected in the optical counterpart to the X-ray source XMMU J004723.7-731226 = RXJ0047.3-7312 = AXJ0047.3-7312= SXP 264 in the Small Magellanic Cloud. This source has been identified with the emission line star [MA93]172 and is coincident with Optical Gravitational Lensing (OGLE) objects 116979 (Phase II) and 45007 (Phase III) (Udalski et al., 1998). We find an optical period of 48.8 +/- 0.6 days in the OGLE data. The modulation has an amplitude of 0.04 mag and a steep rise/slow decay profile similar to other confirmed X-ray binary systems. The relationship between this orbital period and the pulse period of 264s is within the normal variance found in the Corbet diagram (Corbet, 1984).
|
2005-02-06 02:03:00
|
optical,x-ray,binary,gravitational lensing,pulsar,star,transient
|
406
|
Type determination for SN 2005Z and SN 2005aa
|
Avishay Gal-Yam (Caltech)
|
Avishay Gal-Yam reports for the CCCP: A. Soderberg and D. Fox have obtained spectra of the unidentified supernovae SN 2005Z and SN 2005aa, using the double spectrograph mounted on the Palomar Observatory 200" Hale telescope, on Feb. 6, 2005, UT. Preliminary analysis reveals that SN 2005Z (Khandrika, Park, Graham, and Li, IAUC # 8476 ) is of type II. Broad lines of Halpha and Hbeta display a P-Cygni profile. SN 2005aa (Khandrika, Park, Graham, and Li, IAUC # 8476 ) is also of type II, with broad lines of Halpha and Hbeta, mostly in emission, superposed on a blue continuum.
|
2005-02-07 04:22:00
|
optical,supernovae
|
407
|
Spin and Pulsed X-ray Flux Properties of SGR 1806-20 after the Giant Flare
|
Peter M. Woods (USRA/NSSTC), Chryssa Kouveliotou (MSFC/NSSTC), Ersin Gogus (Sabanci Univ), Mark Finger, Sandy Patel (USRA/NSSTC), Jean Swank (NASA/GSFC), and Kevin Hurley (UCB)
|
The Soft Gamma Repeater SGR 1806-20 emitted a giant flare that was recorded on 2004 December 27 (GCN 2920). We triggered an ongoing sequence of ToO observations of the SGR with RXTE that began on 2005 January 22, the earliest RXTE could observe due to Sun-angle constraints. We find no evidence for a sudden change in spin frequency of the SGR following this flare and place a limit on such a frequency jump of |delta nu| < 2 x 10^-5 Hz. On the other hand, the spin-down rate has decreased relative to the pre-flare value. The current frequency derivative is (-3.15 +/- 0.09) x 10^-12 Hz/s, some ~2.7 times smaller than the average value of -8.6 x 10^-12 Hz/s observed over the ~4 years leading up to the flare. Finally, the pulsed flux of SGR 1806-20 is significantly less than it was pre-flare (ATEL 313). Assuming that the pulsed fraction has not changed since before the flare, we infer the current, unabsorbed X-ray flux of SGR 1806-20 to be ~2 x 10^-11 ergs cm^-2 s^-1 (2-10 keV).
|
2005-02-08 07:04:00
|
x-ray,gamma ray,neutron star,soft gamma-ray repeater,star,the sun
|
408
|
Type Determination for SN 2005ac
|
The Nearby Supernova Factory: G. Aldering, B. C. Lee, S. Loken, P. Nugent, S. Perlmutter, J. Siegrist, R. Scalzo, R. C. Thomas, L. Wang (Lawrence Berkeley National Laboratory, Berkeley, CA), G. Adam, R. Bacon, C. Bonnaud, L. Capoani, D. Dubet, F. Henault, B. Lantz, J-P. Lemonnier, A. Pecontal, E. Pecontal (Centre de Recherche Astronomique de Lyon), N. Blanc, G. Boudoul, S. Bongard, A. Castera, Y. Copin, E. Gangler, L. Sauge, G. Smadja (Institut de Physique Nucleaire de Lyon), R. Kessler (Kavli Institute for Cosmological Physics, Chicago, IL), P. Antilogus, P. Astier, E. Barrelet, G. Garavini, S. Gilles, L-A. Guevara, D. Imbault, C. Juramy, R. Pain, R. Taillet, D. Vincent (Laboratoire de Physique Nucleaire et de Haute Energies de Paris), C. Baltay, D. Rabinowitz, A. Bauer (Yale)
|
A spectrum (range 330-990 nm) of SN 2005ac in SDSS J133955.93+005217.1 (Burket and Li, IAUC # 8478 ), obtained on Feb 10.65 UT with the SuperNova Integral Field Spectrograph on the University of Hawaii 2.2m telescope, reveals it to be a Type Ia supernova approximately one week past maximum light. The supernova is similar to SN 2001ay (Nugent et al., IAUC # 7612 ), with very strong Si II absorption features throughout the optical spectrum. Adopting the SDSS redshift of 0.070 for the host galaxy, the supernova expansion velocity is approximately 11,700 km/s for Si II (rest 635.5 nm).
|
2005-02-11 04:22:00
|
optical,supernovae
|
409
|
XMM-Newton observation of M101 ULX-1
|
A. K.H. Kong (MIT)
|
We report XMM-Newton TOO observation of the recent outburst of M101 ULX-1 (CXOU J140332.3+542103; ATEL #374). The observation was taken on 8 January 2005 with an exposure time of 32 ks. With about 20 ks useful data, there are about 1200 counts in EPIC-pn for spectral fitting. The spectrum is very soft and there is no significant X-ray emission above 1 keV. The spectrum has a peak at around 0.4-0.5 keV and can be fitted with an absorbed blackbody model (N_H=1.9e21 cm^-2, kT=56 eV). The absorbed 0.3-2.5 keV luminosity is 4.5e38 ergs/s (d=6.7 Mpc), a factor of 3 lower than the Chandra observation taken on 1 January 2005. The unabsorbed 0.3-7 keV luminosity of the source is about 5.9e39 ergs/s during the XMM-Newton observation, similar to the initial decline stage of the previous outburst in 2004 July (Kong et al. 2004, ApJ, 617, L49). The source spectrum also changed from a quasisoft (Di Stefano and Kong 2004, ApJ, 609, 710) shape (kT=166 eV; ATEL #374) back to a supersoft spectrum (kT=60 eV) during the decline.
|
2005-02-11 08:52:00
|
x-ray,binary,black hole,variables
|
410
|
Seyfert 2 VV 780 detected with INTEGRAL
|
Emrah Kalemci (SSL/UCB), Steven E. Boggs (SSL/UCB), Niels Lund (DNSC)
|
The analysis of the ISGRI / INTEGRAL data of SN 1006 observations yielded an unknown catalog source located at RA=14h57m31s, DEC=-43d10m11s. The source is detected with 8.7 sigma in 20-40 keV band in the mosaic image covering all SN 1006 observations taken in Jan 2004, revolutions 155, 156, 157 and 158 with ~700 ks of data. Subsequent investigation revealed that the Seyfert 2 galaxy VV 780 is in the error circle of ISGRI for the source position.
The ISGRI spectrum obtained using the mosaic image can be fitted with a power law of index 2.2 +- 0.4 and the 20-50 keV flux is 8.8 10^-12 ergs cm^-2 s^-1.
The source was not detected with JEM-X (0.06 mCrab upper limit in 4.2-8.4 keV band), and Seyfert 2s are known to be highly obscured. There is no X-ray source in the ROSAT catalogue within the ISGRI error circle. The SN 1006 observations taken on January 2003 in revolutions 30 and 32 did not show an excess in the ISGRI image at the source position, pointing to variable emission. The 2 sigma upper limit flux in 20 - 50 keV band for these observations is 10^-11 ergs cm^-2 s^-1. The analysis of other public INTEGRAL observations of the source position is underway. As best of our knowledge, this area of the sky has not been observed with modern X-ray satellites, and this is the first detection of the source in hard X-rays. Further observations with other instruments and analysis of the INTEGRAL data will shed light to the nature of variability of this object in X-rays.
|
2005-02-16 02:05:00
|
x-ray,gamma ray,agn,black hole,variables,request for observations
|
411
|
Discovery and Type Identification for New Supernova
|
The Nearby Supernova Factory: G. Aldering, B. C. Lee, S. Loken, P. Nugent, S. Perlmutter, R. Scalzo, R. C. Thomas, L. Wang (Lawrence Berkeley National Laboratory, Berkeley, CA), C. Bonnaud, E. Pecontal (Centre de Recherche Astronomique de Lyon), N. Blanc, S. Bongard, Y. Copin, E. Gangler, L. Sauge, G. Smadja (Institut de Physique Nucleaire de Lyon), R. Kessler (Kavli Institute for Cosmological Physics, Chicago, IL), P. Antilogus, G. Garavini, S. Gilles, R. Pain (Laboratoire de Physique Nucleaire et de Haute Energies de Paris), C. Baltay, D. Rabinowitz, A. Bauer (Yale)
|
The Nearby Supernova Factory reports the discovery of a supernova, SNF20050203-000, with NEAT images taken on the Palomar Oschin Schmidt telescope Feb. 3.45 UT as part of the Palomar-QUEST Survey. At discovery the supernova had an unfiltered magnitude of 18.0. It is located at RA = 10:24:12.9, Dec = -03:44:50.6 (J2000), which is 6.0" W and 0.4" N of the host, LCRS B102141.5-032936. A spectrum (range 330-990 nm) of SNF20050203-000 obtained on Feb. 15.47 UT with the SuperNova Integral Field Spectrograph on the University of Hawaii 2.2m telescope, reveals it to be a Type IIn supernova well after maximum light at the redshift of the host galaxy, z = 0.031. It is similar to SN 1994Y (Clocchiatti et al., IAUC # 6065 ) more than 100 days after discovery. Present in the spectrum are broad emission features (fwhm approximately 5000 km/s) due to H-alpha, H-beta and the Ca II H&K and IR triplet lines.
|
2005-02-16 06:57:00
|
optical,supernovae
|
412
|
The Second Optical Outburst of XTE J1118+480
|
Y. Chou (National Central University), A. Chen (National Cheng Kung University), P. S. Chiang (National Cheng Kung University), C. P. Hu (National Central University), R. H. Hu(National Central University)
|
We report the results from our continuous monitoring of the outbursting black hole X-ray transient XTE J1118+480 (KV UMa, ATEL #383, #384, #385, #386, #387, #389, #393, #399, #402, #404) made by Lulin One-meter Telescope (LOT), Taiwan. After about a month declining to V=17.4, its optical flux was found rising again on Feb 13 and has been increasing since. Our latest data show that the source is ~1 mag brighter than the lowest state on Feb 12. The mean V band magnitudes from Feb. 6 to 16 measured by LOT were: Feb 6.745, 15.01; 7.694, 15.20; 8.733, 15.42; 11.809, 16.48; 12.851, 17.43; 13.831, 16.92, 14.820, 16.57; 15.787, 16.57; 16.782, 16.67. Our discovery implies that the source is on its second outburst state, which is probably similar to its last outburst in 2000. Observations in all wavebands are strongly suggested.
|
2005-02-18 14:40:00
|
optical,x-ray,binary,black hole,transient
|
413
|
GRO J1008-57 Brightening
|
Jean Swank (GSFC) for the RXTE team
|
The transient pulsar GRO J1008-57 may be starting an outburst. On Feb 18.00, the ASM on the Rossi X-Ray timing Explorer (RXTE) detected a flux of 36(3) mCrab. The source first spent a week, starting on Feb 6, at a level of 5 mcrab; it then rose to 20 mcrab on Feb 15. The ASM hardness ratio HR2 is 2.0(0.3), consistent with a pulsar spectrum, in comparison to the Crab at 1, though soft compared to the still active V0332+53. The Gamma-Ray Observatory discovered 93.5 s pulsations in the discovery outburst of July 1993, which reached a peak of 1.4 Crab (Bildsten et al. 1997, ApJS. 113, 367; Shrader et al. 1999, ApJ, 512,920). A probable Be star companion was found at that time (Coe et al. 1994, MNRAS, 270, L57).
|
2005-02-19 08:06:00
|
x-ray,gamma ray,binary,pulsar,star,transient
|
414
|
New Outburst of GRO J1655-40?
|
C. B. Markwardt (U. Maryland & NASA/GSFC) & J. H. Swank (NASA/GSFC)
|
RXTE PCA bulge scan observations on 2005 Feb 17.99 (UT) have detected emission consistent with coming from the black hole transient GRO J1655-40. The flux in the 2-10 keV band was 4.1 +/- 0.6 mCrab. The source was not detected in a previous observation on Feb 10.77 (2-10 keV flux measurement of 0.3 +/- 0.3 mCrab).
A dedicated scan to confirm the position and look at the growth rate is planned for Feb 20.
|
2005-02-20 05:15:00
|
x-ray,binary,black hole,transient,request for observations
|
415
|
GRO J1655-40 Flux is Rising (Slowly)
|
C. B. Markwardt (U. Maryland & NASA/GSFC), E. Smith & J. H. Swank (NASA/GSFC)
|
Dedicated RXTE/PCA scans of the region around GRO J1655-40 (ATEL #414) were performed on Feb 20 around 09h UT.
The scans show only one source in the region, whose position is consistent with GRO J1655-40 to within 4 arcmin (2.5 sigma). The 2-10 keV flux has risen to approximately 8 mCrab (compare to 4 mCrab on Feb 18, ATEL #414). No pulsations were detected, ruling out the presence of a transient pulsar. The spectrum was fitted by a power law with photon index 1.9, corresponding to a 10-40 keV flux of 14 mCrab.
|
2005-02-21 04:11:00
|
x-ray,binary,black hole,pulsar,transient
|
416
|
The orbital period of CI Cam (XTE J0421+560)
|
E. A. Barsukova, N. V. Borisov, A. N. Burenkov, V. G. Klochkova (Special Astrophysical Observatory, Russia), V. P. Goranskij, N. V. Metlova (Sternberg Astronomical Institute, Moscow University)
|
CI Cam is a known B[e] star and X-ray transient. We perform photometric and medium-resolution spectroscopic monitoring of CI Cam in the quiet state during 7 years since April 1998 outburst. We have detected orbital light variations with the period of 19.41+/-0.02 day. The modulation has an amplitude of 0.032 mag in V band. The epoch of maximum is at JD 2452200.75. We find large regular variations of the radial velocity in HeII 4686A emission line with this photometric period. The velocity curve has a sawtooth shape and a semi-amplitude of about 230 km/s with gamma-velocity at -51 km/s. Modelling of the velocity curve results in the orbital eccentricity of about 0.62, and a*sin(i) ~42 million km. The inferior conjunction epoch is at JD 2452199.6+/-0.2, and periastron passage occurs near the moment of inferior conjunction. Maximum brightness occurs 0.06P later by phase. Mass function of HeII emission source is equal to 12 solar masses. This is a lower limit on the primary star mass, the spectrum of which we define as B4 III-V. We have not found any detectable motion in a HeI line that may belong to the primary B type star. So, the fast moving HeII emitting object should have at least 25 times smaller mass than the primary star. More likely this object is a white dwarf surrounded by an accretion disk.
|
2005-02-21 04:40:00
|
optical,x-ray,binary,star,transient,variables
|
417
|
A NIR Observation of GRO J1655-40
|
M. A.P. Torres (CfA), D. Steeghs (CfA), P. Jonker (SRON), P. Martini (CfA)
|
Following ATEL #414, on February 20.39 UT we acquired a J-band image of the X-ray transient GRO J1655-40 using the PANIC camera on the 6.5-m Magellan-Baade telescope at Las Campanas Observatory. Preliminary relative photometry with respect to ten 2MASS nearby stars yields J=13.2 +/- 0.1, indicating that GRO J1655-40 is brighter by at least ~0.5 mag in J relative to its magnitude in quiescence (J=13.7-14; Greene, Bailyn & Orosz 2001,ApJ,554,1290). This suggests that GRO J1655-40 is indeed the rising X-ray source reported in ATEL #414 and #415.
|
2005-02-21 11:05:00
|
infra-red,x-ray,binary,black hole,star,transient,request for observations
|
418
|
Optical and NIR observations of GRO J1655-40
|
Michelle Buxton, Charles Bailyn, Dipankar Maitra (Yale University)
|
In response to the recent report of renewed activity in GRO J1655-40 (ATEL #414), we have obtained B, V, I, J and K-band images using the ANDICAM instrument on the SMARTS 1.3m telescope at CTIO. On UT Feb 21.3-21.4 we measure the following magnitudes: B = 18.5, V = 17.0, I = 14.9, J = 13.4, K = 12.4. In comparison to the average quiescent magnitudes (Greene, Bailyn & Orosz 2001, ApJ, 554, 1290), we find the following differences in magnitude: dB = 0.3, dV = 0.2, dI = 0.2, dJ = 0.5, dK = 0.9. Our dJ agrees with that of Torres et al. (ATEL #417). The B and V mags are within the amplitudes of the quiescent ellipsoidal variations, the I mag is just above. The J and K mags, however, are well outside the ellipsoidal variations. Hence, we confirm that GRO J1655-40 is entering a new active phase. The strong IR rise suggests that we may be in the early stages of an outburst like that of 1997, when Orosz et al. (1997, ApJ, 478, L83) noted a rise in the red bands that preceded the rise in the bluer bands. This might also be an IR flare like that described by Buxton & Bailyn (2004, ApJ, 615, 880) in 4U 1543-47. Multiwavelength observations, particularly radio, would be very desirable. We will be monitoring this object on a daily basis with SMARTS.
|
2005-02-22 03:09:00
|
radio,infra-red,optical,binary,black hole,transient
|
419
|
Radio detection of GRO J1655-40
|
M. P. Rupen (NRAO/GSFC), V. Dhawan, A. J. Mioduszewski (NRAO)
|
We report the detection of renewed radio activity associated with the black hole X-ray binary GRO J1655-40, currently undergoing an X-ray (ATEL #414; ATEL #415) and optical/infrared (ATEL #417, ATEL #418) flare. Very Large Array (VLA) observations taken on Feb. 20th (MJD 53421.6) under poor weather conditions clearly detect a 1.4+/-0.2 mJy source at the position of GRO J1655-40 at 4.86 GHz, and a corresponding 1.1+/-0.4 mJy source (uncertainties dominated by phase errors) at 8.46 GHz. There is no obvious extension with our 5.35 x 2.67 arcsec beam (oriented -5 degrees east of north) at 4.86 GHz; the 8.46 GHz do not place any useful limit. Our last previous observations were made on 4 January 2005 (MJD 53374.6) at 4.86 GHz, yielding a non-detection with an rms noise of 0.13 mJy/beam. Further radio observations are planned.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
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2005-02-22 03:44:00
|
radio,optical,x-ray,binary,black hole,transient
|
420
|
No radio re-flare in XTE J1118+480
|
M. P. Rupen (NRAO/GSFC), V. Dhawan, A. J. Mioduszewski (NRAO)
|
We report recent radio observations of the X-ray binary XTE J1118+480, recently reported as undergoing a second optical outburst (ATEL #412) following a more impressive optical (ATEL #383, ATEL #386, ATEL #393, ATEL #399, ATEL #402), X-ray (ATEL #384, ATEL #390), and radio (ATEL #385, ATEL #387, ATEL #400, ATEL #404) flare. Very Large Array (VLA) observations taken at the beginning of the infrared recovery, on Feb. 13th (MJD 53414.2), gave non-detections with rms noise levels of 0.072 and 0.045 mJy/beam at 4.86 and 8.46 GHz, respectively. Observations on Feb. 20th (MJD 53421.5) also showed no radio source, with rms noise levels of 0.061 (4.86 GHz) and 0.035 (8.46 GHz) mJy/beam. Our last detection of this source was on Feb. 6th (MJD 53407.5), with flux densities at 4.86 and 8.46 GHz of 0.45+/-0.07 and 0.33+/-0.07 mJy, and no detection at 22.46 GHz, with an rms noise of 0.31 mJy/beam. The overall radio light curves, shown at
show a roughly linear decay since Jan. 24th (MJD 53394). Further observations are planned.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
|
2005-02-22 04:08:00
|
radio,optical,x-ray,binary,black hole,transient
|
421
|
Discoveery of a nova in M31
|
A. Dimai (Col Druscié Observatory, Italy), F. Manzini (Stazione Astronomica di Sozzago, MPC code A12, Italy)
|
Marco Migliardi, Col Drusciè Observatory (Italy), report the discovery of an apparent nova in M31 (NGC 224) on behalf of the CROSS Program with the 0.5-m telescope of the Col Drusciè Observatory. The possible nova was found on unfiltered CCD images (Kodak KAF-1602E CCD) taken on February 18.77 (mag. 17.7), and confirmed by other 5 images, last taken on February 18.78 . The object is located about 128"E and 99"S of the galaxy nucleus, at RA 00h42m52.764s and DEC +41d 14m 29s. CROSS images taken on November 09.9, 2004 shows nothing at the position of the apparent nova (limiting mag about 18,5) and SAS (Stazione Astronomica di Sozzago SN search) images taken on January 01.8, 2005 shows nothing at the position of the apparent nova (limiting mag about 20,0). The object shows no motion, moreover no known minor planets, brighter than V = 19.0, were found in the area by SN Minor-Planet Checker on 2005 02 18.77 UT. An image of the object can be observed at: http://www.aac.sunrise.it/cross/NovaM31/novaM31-200502a.htm
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2005-02-22 16:00:00
|
optical,nova,planet,star,variables
|
422
|
INTEGRAL observation of GRO J1655-40
|
N. Produit (ISDC), S. Shaw (ISDC), P. Jean (CESR),K. Kretschmer(MPG)
|
During INTEGRAL observations of the Galactic Disk, the superluminal source GRO J1655-40 was observed with the ISGRI detector. The source was detected in 5 ~2000second long pointings between 2005-02-18 and 2005-02-19 at a flux between 3 and 4 cps in the 20-50 keV band (corresponding to approx 30mCrab). This measurement confirms that of ATEL 415 and 414, which showed that the source is slowly brightening in the 2-10 keV band.
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2005-02-22 23:49:00
|
gamma ray,binary,star,transient,variables
|
423
|
Discovery of CV ROTSE3 J100932.2-020155
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E. Rykoff (U. Mich.) and R. Quimby (U. Texas) on behalf of the ROTSE collaboration
|
Online analysis of ROTSE-III sky patrol fields reveals a new CV we designate ROTSE3 J100932.2-020155. The object was first detected on 20 Jan 2005 by the ROTSE-IIIb telescope at McDonald Observatory, Texas at an unfiltered magnitude m_R = 14.3. It has since stayed brighter than m_R=15 and has been imaged by ROTSE-IIIa at Siding Spring Observatory, Australia and ROTSE-IIIc at the H.E.S.S. site in Namibia, with the most recent detection on 22 Feb. The 2df survey had targeted the object (m_b=20.5) as a possible quasar, and took two spectra. The spectra are consistent with a quiescent galactic CV. On 20 Feb we took a spectrum during outburst with the HET. The object has a blue continuum with prominent H-alpha emission. This object is consistent with a SU UMa Dwarf Nova during a super outburst. Further information including a light curve can be found at http://www.rotse.net/transients/j1009/index.html
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2005-02-23 00:33:00
|
optical,cataclysmic variable,nova,quasar,transient,variables
|
424
|
New Optical Observations of XTE J1118+480
|
C. Zurita, T. Muñoz-Darias, I. G.MartÃnez-Pais, J. Casares, P. RodrÃguez-Gil, T. Shahbaz (Instituto de AstrofÃsica de Canarias) and M. A.P. Torres, P. Zhao, D. Steeghs, M. R. Garcia (Harvard-Smithsonian Center for Astrophysics)
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We report on new R-band photometry of the outbursting black hole candidate XTE J1118+480 (ATEL #383, #384) obtained with the 4.2m WHT at the Observatorio del Roque de los Muchachos (La Palma) and with the FLWO 1.2m telescope on Mt. Hopkins. We measure the following average magnitudes: Feb 20.19 (UT), R=16.94 +/- 0.06; Feb 21.18, R=17.41 +/- 0.06; Feb 21.49, R=17.58 +/-0.07; Feb 22.26, R=18.08 +/- 0.06. The data show that XTE J1118+480 continues its decline to quiescence. The previous claim of a second outburst (ATEL #412) is more likely an optical reflare or minioutburst with no X-ray counterpart like those observed in other X-ray transients such as XTE J1859+226 (Zurita et al. 2002,MNRAS,334,999).
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2005-02-23 08:48:00
|
optical,x-ray,binary,black hole,transient
|
425
|
Radio holding steady in GRO J1655-40
|
M. P. Rupen (NRAO/GSFC), A. J. Mioduszewski, V. Dhawan(NRAO)
|
Very Large Array (VLA) observations of the black hole X-ray binary GRO J1655-40 on Feb. 23rd (MJD 53424.6) show that the radio source seen on Feb. 20th (ATEL #419) has remained roughly constant, with flux densities of 1.53 +/- 0.07 mJy at 4.86 GHz, and 1.45 +/- 0.08 mJy at 8.46 GHz. These data, taken in much better weather conditions, show a fairly flat spectrum (flux density going as frequency to the -0.10 +/- 0.14), suggesting a very small (milliarcsecond or less) source. A Gaussian fit to the 8.46 GHz data yields a more direct upper limit to the size of about 1.1 arcseconds, compared to the 2.6 x 0.6 arcsec full-width-at-half-maxmimum of the beam (major axis oriented 6.1 degrees east of north). Further radio observations are planned.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
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2005-02-24 06:17:00
|
radio,x-ray,binary,black hole,transient
|
426
|
Binary period in Optical counterpart to CXOU J005455.6-724510 = RXJ0054.9-7245 = AX J0054.8-7244 = SXP504
|
W. R.T. Edge, M. J. Coe, J. L. Galache and V. A. McBride (Southampton University), R. H.D. Corbet (GSFC and USRA), C. B. Markwardt (GSFC and University of Maryland), S. Laycock (CfA), F. E. Marshall (GSFC)
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A probable binary period has been detected in the optical counterpart to the X-ray source CXOU J005455.6-724510 = RX J0054.9-7245 = AXJ0054.8-7244 = SXP504 in the Small Magellanic Cloud. This source was detected by Chandra on 04 Jul 2002 (MJD 52459) and first reported in ATEL#217. It was subsequently observed by XMM-Newton on 18 Dec 2003 (MJD 52991) (ATEL#219). The source is coincident with the Optical Gravitational Lensing (OGLE) object numbered 47103 (in Phase II) and 36877 (in Phase III) (Udalski et al., 1998). Several probable optical outburst peaks are visible in these light curves at ~268 day intervals. Timing analysis shows a period of 261 ± 7 days at >99% significance. A search of archival RXTE PCA data for the 504s pulse-period revealed detections at MJDs 50802, 51652, 51870, 52165, 52612 and 52978 which correspond closely with predicted or actual peaks in the optical data. This source is also coincident with MACHO object 207.16245.16 (Alcock et al., 1999) in which there is some evidence for a weak period at around 268 days. All these observations can be described by an ephemeris of T= (MJD 50556 ± 3) + n (268 ± 1.4) where T is the epoch of the outburst and n is the outburst cycle number. Nearly all the X-ray detections are at the predicted optical ephemeris, but because of non-continuous X-ray coverage others may well have been missed. The relationship between this orbital period and the pulse period of 504s is within the normal variance found in the Corbet diagram (Corbet, 1984).
|
2005-02-25 02:17:00
|
optical,x-ray,binary,gravitational lensing,pulsar,transient
|
427
|
Type determination for SN 2005ak
|
The Nearby Supernova Factory: G. Aldering, B. C. Lee, S. Loken, P. Nugent, S. Perlmutter, R. Scalzo, R. C. Thomas, L. Wang (Lawrence Berkeley National Laboratory, Berkeley, CA), C. Bonnaud, E. Pecontal (Centre de Recherche Astronomique de Lyon), N. Blanc, S. Bongard, Y. Copin, E. Gangler, L. Sauge, G. Smadja (Institut de Physique Nucleaire de Lyon), R. Kessler (Kavli Institute for Cosmological Physics, Chicago, IL), P. Antilogus, G. Garavini, S. Gilles, R. Pain (Laboratoire de Physique Nucleaire et de Haute Energies de Paris), C. Baltay, D. Rabinowitz, A. Bauer (Yale)
|
The Nearby Supernova Factory reports that a spectrum (range 340-1000 nm) of SN 2005ak (CBET #110), obtained Feb 25.66 UT with the SuperNova Integral Field Spectrograph on the University of Hawaii 2.2m telescope, shows it to be a type Ia SN just before maximum light. Assuming a host redshift of z =0.027 from NED and SDSS, the Si II 635.5 nm minimum absorption is at approximately 10,000 km/s.
|
2005-02-26 03:17:00
|
optical,supernovae
|
428
|
XTE J1118+480 near Quiescence
|
C. Zurita, J. Casares, T. Muñoz-Darias, P. RodrÃguez-Gil, I. G. MartÃnez-Pais, T. Shahbaz (Instituto de AstrofÃsica de Canarias) and M. A. P. Torres, P. Zhao, D. Steeghs, M. R. Garcia (Harvard-Smithsonian Center for Astrophysics)
|
Following our optical monitoring of the halo black-hole candidate XTE J1118+480 (ATELs #383, #402, #424), we have obtained time-resolved R-band photometry with the ESA 1-m OGS telescope at the Spanish Observatorio del Teide and with the FLWO 1.2m telescope on Mt. Hopkins. Our observations show that the source has settled into a near-quiescence level, about 0.6-mag brighter than in true quiescence (R~18.9; IAUC # 7868 ). The light curve obtained on 2005 UT Feb 25.90-26.27 is consistent with a double-humped ellipsoidal modulation with an orbital period of 0.17+/-0.01 d and a ~0.35 mag peak-to-peak amplitude. Additionally, the light curve is distorted from a pure ellipsoidal variation suggesting the presence of superhumps, like those observed in the near-quiescence state at the end of the 2000 outburst (Zurita et al. 2002, MNRAS, 333, 791).
|
2005-02-28 10:16:00
|
optical,binary,black hole,transient
|
429
|
Optical counterpart to IGR J16465-4507
|
Ignacio Negueruela (Alicante), David M. Smith (U. C. Santa Cruz), Sylvain Chaty (CEA-Saclay)
|
Intermediate resolution spectra of the only star in the XMM-Newton error box for IGR J16465-4507 (ATel #329, #336), USNO-B1.0 0448-00520455 = 2MASS J16463526-4507045, have been taken with the 3.5-m NTT, in La Silla (ESO proposal 274.D-0510). As anticipated in ATel #338, the star is a reddened early-type supergiant and hence certainly the correct counterpart.
The spectral type is estimated at B0.5I. The H-alpha line shows a broad emission component on top of the photospheric profile.
It seems clear now that XTE J1739-302, IGR J17544-2619 and IGR J16465-4507 define a new class of high mass X-ray transients, characterised by very short outbursts and evolved counterparts (cf. Atel #338).
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2005-03-01 01:56:00
|
optical,x-ray,binary,neutron star,star,transient
|
430
|
Type determination for SN 2005al
|
The Nearby Supernova Factory: G. Aldering, B. C. Lee, S. Loken, P. Nugent, S. Perlmutter, R. Scalzo, R. C. Thomas, L. Wang (Lawrence Berkeley National Laboratory, Berkeley, CA), C. Bonnaud, E. Pecontal (Centre de Recherche Astronomique de Lyon), N. Blanc, S. Bongard, Y. Copin, E. Gangler, L. Sauge, G. Smadja (Institut de Physique Nucleaire de Lyon), R. Kessler (Kavli Institute for Cosmological Physics, Chicago, IL), P. Antilogus, G. Garavini, S. Gilles, R. Pain (Laboratoire de Physique Nucleaire et de Haute Energies de Paris), C. Baltay, D. Rabinowitz, A. Bauer (Yale)
|
The Nearby Supernova Factory reports that a spectrum (range 340-1000 nm) of SN 2005al (IAUC # 8488 ), obtained Feb 28.54 UT with the SuperNova Integral Field Spectrograph on the University of Hawaii 2.2m telescope, shows it to be a type Ia SN, most likely near maximum light. Assuming a host redshift of z =0.0124 from NED, the Si II 635.5 nm minimum is at approximately 11,000 km/s, and the Ca II infrared triplet absorption extends to a high velocity of 22,500 km/s.
|
2005-03-01 03:54:00
|
optical,supernovae
|
431
|
Type Refinement for SN 2005U in Arp 299
|
D. C. Leonard and S. B. Cenko (Caltech)
|
D. C. Leonard and S. B. Cenko report on behalf of the CCCP that a prelinarily reduced spectrum (range 5500 - 9500 A) of the previously identified Type II SN 2005U (Mattila et al., IAUC # 8473 ; Modjaz et al., IAUC # 8475 ) obtained using the double spectrograph mounted on the Palomar Observatory 200" Hale telescope, on Feb. 28, 2005, UT, shows it to resemble the spectrum of the Type IIb SN 1993J over a month past explosion (Matheson et al. 2000, AJ, 120, 1487). In addition to features typically seen in SNe II at this epoch, lines of He I with P-Cyg profiles have emerged, most notably those of 6678 and 7065 in our spectrum. This suggests that the progenitor of SN 2005U lost a substantial fraction of its hydrogen envelope prior to exploding.
|
2005-03-01 07:01:00
|
optical,supernovae
|
432
|
INTEGRAL follow-up of GRO J1655-40
|
I. Brott (ISDC/Hamburg Observatory), J. Swank (GSFC), N. Mowlavi (ISDC, Geneva Observatory), C. Shrader (GSFC/USRA)
|
A Target Of Opportunity observation of the X-ray binary GRO J1655-40 was triggered with INTEGRAL from 2005 February 24, 05h30 UTC to February 28, 12h30 UTC.
The source was detected in the ISGRI instrument with a significance of about 15 sigma. The Quick Look Analysis (QLA) found the flux slowly increased during the first three days of the observation, from ~30 mCrab to ~60 mCrab in the 20-60 keV energy band and from ~40 mCrab to ~90 mCrab in the 60-200 keV band (15% accuracy level). No clear evidence for further increase was seen in the QLA lightcurves after February 27, 05h00.
During the intervals when the source was in its field of view, JEM-X established upper limits of 20 mCrab in 1 hour integrations of 3-10 keV. These are consistent with contemporaneous RXTE PCA detections of about 16 mCrab.
|
2005-03-01 20:08:00
|
x-ray,gamma ray,binary,black hole,transient
|
433
|
Continued RXTE observations of GRO J1655-40
|
J. Swank (GSFC) and C. Markwardt (UMD/GSFC)
|
GRO J1655-40 has been observed with the RXTE pointed instruments each day during Feb 21-Mar 1. The flux has risen only slowly during this period: The 2-10 keV and 10-60 keV flux fluxes on Feb 21.9 were 8.4 and 16.7 mCrab, respectively, and on Feb 27.9 were 17.1 and 36.1 mCrab. During a period of 3 hr Feb 27.96-28.10 there was a sequence of dips by as much as 50%, a phenomenon discovered during 1997 observations (Kuulkers et al. 1998, ApJ, 494, 753).The flux Mar 1 was the same as that of Feb 26, confirming the plateau noted for the INTEGRAL data (ATEL #432). Most of the flux has been in a power law of index 1.66+/- 0.05. Outside the dips at least, no iron line emission is required in the fits.
|
2005-03-01 21:12:00
|
x-ray,binary,black hole,transient
|
434
|
Continued slow radio rise of GRO J1655-40
|
M. P. Rupen (NRAO/GSFC), A. J. Mioduszewski, V. Dhawan (NRAO)
|
We report further Very Large Array (VLA) observations of the black hole X-ray binary GRO J1655-40. Data taken on Feb. 27th from 11:40 through 13:40 UT (during the X-ray plateau seen by INTEGRAL [ATEL #432] and RXTE [ATEL #433]) show the radio source steady to within 10%, with flux densities of 1.86 +/- 0.17, 1.80 +/- 0.06, and 1.57 +/- 0.05 mJy at 1.425, 4.860, and 8.460 GHz, respectively. Quasi-simultaneous observations at 22.460 GHz were not useful, due to a combination of weather conditions and the low elevation of the source. The radio source has continued its roughly linear rise since the first radio detection on Feb. 20th (ATEL #419), and retains a fairly flat (optically thick) spectrum. The slow (~30%) rise in the radio contrasts with the X-ray flux, which has roughly doubled over the same period (ATEL #433) in both the 2-10 and 10-60 keV bands. Further radio observations are planned, and will be posted (together with the results so far) at:
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
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2005-03-01 23:41:00
|
radio,x-ray,binary,black hole,transient
|
435
|
Type Determination for SN in ESO 506-G011
|
The Nearby Supernova Factory: G. Aldering, B. C. Lee, S. Loken, P. Nugent, S. Perlmutter, R. Scalzo, R. C. Thomas, L. Wang (Lawrence Berkeley National Laboratory, Berkeley, CA), C. Bonnaud, E. Pecontal (Centre de Recherche Astronomique de Lyon), N. Blanc, S. Bongard, Y. Copin, E. Gangler, L. Sauge, G. Smadja (Institut de Physique Nucleaire de Lyon), R. Kessler (Kavli Institute for Cosmological Physics, Chicago, IL), P. Antilogus, G. Garavini, S. Gilles, R. Pain (Laboratoire de Physique Nucleaire et de Haute Energies de Paris), C. Baltay, D. Rabinowitz, A. Bauer (Yale)
|
The Nearby Supernova Factory reports that a spectrum (range 340-1000 nm) of the supernova in ESO 506-G011 (Weidong Li, private communication), obtained Mar 4.46 UT with the SuperNova Integral Field Spectrograph on the University of Hawaii 2.2-m telescope, shows it to be a very young Type II. The spectrum is very blue and practically featureless, save for the presence of very weak H-alpha and He I (587.6 nm) P-Cygni lines.
|
2005-03-05 01:39:00
|
optical,supernovae
|
436
|
GRO J1655-40 Rising Again
|
C. Markwardt (U. Maryland & NASA/GSFC), J. Homan (MIT), J. Swank (NASA/GSFC)
|
RXTE has continued to observe GRO J1655-40 since Mar 1 (ATEL #433). The X-ray flux reached an intermediate low point on Mar 2 (19-22 mCrab, 2-10 keV), and has since been rising, with fluxes of 27, 29, 39 and 44 mCrab on Mar 3.8-4.0, 4.0-4.1, 4.9-5.1, 5.7, respectively (UT). Occasional dipping behavior is still present, with a maximum amplitude of ~40%.
The spectrum has remained primarily a power law with photon index 1.4-1.6. As the flux has risen, there is evidence for a softer component, consistent with a black body with a kT of ~1 keV.
A QPO has become more distinct. The centroid frequency of the QPO has increased from 0.17 to 0.31 Hz. These spectral and temporal changes may indicate a state change of the source is occurring.
|
2005-03-07 01:39:00
|
x-ray,binary,black hole,transient
|
437
|
Complex evolution of radio spectrum in GRO J1655-40
|
M. P. Rupen (NRAO/GSFC), V. Dhawan, A. J. Mioduszewski (NRAO)
|
The radio spectrum of the black hole X-ray binary GRO J1655-40 has undergone rapid changes over the past few days, according to observations by the Very Large Array (VLA). On Mar. 4th, data taken between 12:09 and 12:41 UT give flux densities of 1.2 +/- 0.2, 1.9 +/- 0.1, and 1.5 +/- 0.1 mJy at 1.425, 4.860, and 8.460 GHz, respectively; on Mar. 6th, observations between 12:16 and 12:56 UT yield values of 1.8 +/- 0.2, 1.3 +/- 0.1, and 1.2 +/- 0.1 mJy at the same frequencies. Combined with previous observations (ATEL #419, ATEL #425, ATEL #434) these data suggest a small radio flare sometime between Feb. 27th and Mar. 4th (i.e., during or just after the X-ray plateau, ATEL #432, ATEL #433), followed by a return to the earlier fairly flat spectrum. The radio light curve is posted at:
Further radio observations are planned.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
|
2005-03-08 03:33:00
|
radio,x-ray,binary,black hole,transient
|
438
|
Announcement of INTEGRAL Galactic Bulge monitoring program and (re)brightening of GRO J1655-40
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E. Kuulkers (ESA/ESAC, Spain), S. Shaw (ISDC, Geneva), A. Paizis (ISDC Geneva/IASF Milano), N. Mowlavi, T. Courvoisier (ISDC, Geneva), K. Ebisawa (NASA/GSFC, USA), P. Kretschmar (ESA/ESAC, Spain), C. Markwardt (NASA/GSFC, USA),T. Oosterbroek, A. Orr (ESA/ESTEC, Netherlands) & R. Wijnands (UvA, Netherlands)
|
The Galactic Bulge is a region rich in bright and variable high-energy X-ray and gamma-ray sources. From February 17, 2005 and onwards we will observe this region regularly, using the European gamma-ray satellite INTEGRAL, during all the Galactic Bulge visibility periods under an approved AO-3 proposal (PI: Kuulkers). One complete hexagonal dither pattern (7 pointings of 1800 sec each) is performed during each INTEGRAL revolution (i.e., every 3 days). As a service to the scientific community, the IBIS/ISGRI and JEM-X light curves in two energy bands (20-60 keV, 60-150 keV and 3-10 keV, 10-25 keV, respectively) of the sources detected in the field of view, as well as IBIS/ISGRI mosaic images, are made publicly available as soon as possible after the observations are performed. The results, as well as more information about the program, can be retrieved from http://isdc.unige.ch/Science/BULGE/.
As a first result, we report that the recently active black-hole X-ray transient GRO J1655-40 (ATel #414, and following ATels) has increased considerably in flux on 2005 March 8.0-8.2 (~225 mCrab; 20-60 keV), with respect to our observations on March 2.5-2.7 (~65 mCrab; 20-60 keV) and March 5.7-5.9 (~125 mCrab; 20-60 keV), as well as previous INTEGRAL observations (ATel #422, #432). This supports the recent (re)brightening reported by RXTE (ATel #436).
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2005-03-08 23:19:00
|
x-ray,gamma ray,binary,black hole,globular cluster,neutron star,soft gamma-ray repeater,star,transient,variables
|
439
|
Flux variability from the likely IR counterpart of SGR 1806-20
|
G. L. Israel (INAF AO Roma), S. Covino (INAF AO Milano), S. Mereghetti (INAF IASF Milano), R. Mignani (ESO), L. Stella (AO Roma), V. Testa (AO Roma), G. Marconi (ESO), on behalf of a larger team
|
Following the refined radio position of SGR 1806-20 (Gaensler et al., astro-ph/0502393; Cameron et al., astro-ph/0502428), about 0.5" away from the preliminary one (Kouveliotou et al. 2005, GCN \#2929), we note that the possible counterpart we tentatively identified (Israel et al., ATel \#378) is not anymore included in the radio positional uncertainty region.
Only one relatively faint object falls within the refined radio position regions, while two additional objects are just outside. The former object is consistent with the Chandra error circle (radius of 0.3") reported by Kaplan et al. 2002 (ApJ, 564, 935). Moreover, it is the only one to show a constant brightening during 2004, with the highest magnitude recorded just after the intense SGR 1806-20 burst occurred on 5th October 2004. The likely counterpart of SGR 1806-20 has an average Ks magnitude of about 19.01+\-0.07 (1sigma uncertainty is reported) and displays a Ks variation of about 0.7 mags on a 7 months baseline. The IR flux variation is roughly of the same order of that shown during the same period by the persistent X-ray emission of SGR 1806-20 (Mereghetti et al., astro-ph/0411695).
We note that the candidate counterpart plus the two closest objects (Ks=18.0 and Ks=18.3, respectively) are all within a radius of less than 0.2" and consistent with being unresolved components of candidate B in the IR images of Eikenberry et al. (2001, ApJ, 563, L133).
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2005-03-11 05:08:00
|
radio,infra-red,x-ray,gamma ray,soft gamma-ray repeater
|
440
|
GRO J1655-40 rapidly evolving
|
Jeroen Homan (MIT)
|
Daily RXTE/PCA observations of GRO J1655-40 show that the source is rapidly evolving. Between March 5.7 (ATel #436) and March 10.7 the 2-25 keV flux gradually increased by a factor of 5.2, to 8.2e-9 erg/s/cm^2, with the spectral power-law index increasing from ~1.5 to ~1.7 and the QPO frequency from 0.31 Hz to 2.3 Hz.
On March 11.7 the flux had suddenly increased by a factor of 3.2 in a single day, to 2.6e-8 erg/s/cm^2. The spectrum was also much softer, with a power-law index of ~2.2 and a prominent thermal disk component (kT~1.1 keV). The March 11.7 power spectrum showed evolution on a time scale of a few thousand seconds. QPOs were detected at ~3.3 Hz and ~6.8 Hz, with indications for features around 0.07 Hz and 260 Hz.
The sudden softening and increase in flux indicate that the source may soon (within a few days) make a transition to the steep power-law state (McClintock & Remillard 2005, astro-ph/0306213). Such transitions often result in major changes in the optical/IR spectrum of black holes, as well as in strong radio flares. Radio, optical and near-IR observations of GRO J1655-40 in the next few days are therefore strongly encouraged. RXTE will keep observing the source on a daily basis.
RXTE/PCA light curves and hardness curves of the source can be found at: http://tahti.mit.edu/opensource/1655
I will try to update the page on a daily basis.
|
2005-03-13 04:24:00
|
radio,optical,x-ray,binary,black hole,transient,request for observations
|
441
|
GRO J1655-40 radio counterpart fades
|
M. P. Rupen (NRAO/GSFC), A. J. Mioduszewski, V. Dhawan (NRAO)
|
The radio counterpart to the black hole X-ray binary GRO J1655-40 has faded considerably over the past few days. Observations by the Very Large Array (VLA) taken on March 14th, from 12:25 to 12:35 UT, gave no detection, with a nominal flux density at the location of the source of 0.15 +/- 0.14 mJy/beam at 8.46 GHz. The full radio light curve is shown at:
This radio cutoff corresponds to the X-ray rise and softening reported in ATEL #440. Further VLA observations are scheduled for March 16th and 18th; those results will be added to the plot referenced above, and any renewed radio activity will be reported in another Astronomer's Telegram.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
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2005-03-15 04:04:00
|
radio,x-ray,binary,black hole,transient
|
442
|
INTEGRAL observes fading of GRO J1655-40 above 20 keV
|
S. Shaw (Southampton, UK & ISDC, Geneva), E. Kuulkers (ESA/ESAC, Spain), A. Paizis (ISDC, Geneva & IASF, Milano), N. Mowlavi (ISDC, Geneva), T. Courvoisier (ISDC, Geneva), K. Ebisawa (NASA/GSFC, USA), P. Kretschmar (ESA/ESAC, Spain), C. Markwardt (NASA/GSFC, USA),T. Oosterbroek (ESA/ESTEC, Netherlands), A. Orr (ESA/ESTEC, Netherlands) & R. Wijnands (UvA, Netherlands)
|
We have observed a decrease in the the hard X-ray flux (above 20 keV) from the black hole binary GRO J1655-40, of about a factor of two (in four days), using INTEGRAL. This object has been observed for ~12 ksec approximately every 3 days since 17 Feb 2005 during the INTEGRAL Galactic Bulge Monitoring observations ( ATel #438 ).
In the latest observation, on MJD 53444.2 (15 March 2005), the measured flux in the ISGRI instrument was ~18 and ~5 cps in the 20--60 and 60--150 keV bands respectively. In the same energy bands the Crab gives about 180 and 50 cps, so both measurements correspond to ~100 mCrab.
In the previous observation, on MJD 53440.0 (11 March 2005) at the peak of the recent activity, the average flux was more than 2 times higher at ~48 cps in 20--60 keV (~270 mCrab) and ~11 cps (~220 mCrab) in 60--150 keV.
The fading of the hard X-ray flux from this source accompanies the decrease in the radio reported in ATel #441 and the apparent softening of the 2--25 keV RXTE/PCA spectrum given in ATel #440.
Note that the source was observed at a large off-axis angle (~ 15 degrees) and so is in the partially coded field of view of ISGRI and is not visible with JEM-X.
Light curves and images can be found at the following web page and will be updated as soon as possible after following INTEGRAL Galactic Bulge Monitoring observations, which are conducted every 3 days:
http://isdc.unige.ch/Science/BULGE
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2005-03-17 01:12:00
|
radio,x-ray,gamma ray,binary,black hole
|
443
|
Renewed radio emission from GRO J1655-40
|
M. P. Rupen (NRAO/GSFC), V. Dhawan, A. J. Mioduszewski (NRAO)
|
The radio counterpart to the black hole X-ray binary GRO J1655-40 has again re-appeared, and is growing stronger (cf. ATEL #441). Observations taken at 4.86 GHz with the Very Large Array (VLA) showed a 1.77 +/- 0.07 mJy source on March 16th (13:38 to 14:29 UT), and a 3.6 +/- 0.1 mJy source on March 18th (12:59 to 13:10 UT). The latter represents the strongest radio emission so far during the current outburst. The radio emission remains optically thick, with a flux density at 8.46 GHz of 3.8 +/- 0.2 mJy on March 18th (13:19-13:26 UT), implying a quite small source. The full radio light curve is shown at:
This radio re-appearance corresponds to the X-ray hardening visible in the XTE data (see the Web page referenced in ATEL #440). Further VLA observations will be added to the Web page referenced above, with any new surprises reported in another Astronomer's Telegram.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
|
2005-03-19 05:01:00
|
radio,x-ray,binary,black hole,transient
|
444
|
New X-ray transient IGR J1709.8-3628 discovered with INTEGRAL
|
S. A. Grebenev (IKI, Moscow), S. V. Molkov (IKI, Moscow), R. A. Sunyaev (IKI, Moscow; MPA, Garching)
|
We report on the discovery with INTEGRAL of a probable new hard X-ray source located 9.4 arcmin off IGR J17091-3624. This source, IGR J1709.8-3628, was detected with IBIS/ISGRI on March 24.33-25.58, 2005 (UT) during deep Open Program observations of the Galactic center region. The S/N ratio at the mosaic image was 22.3 in the 18-45 keV band and 14.5 in the 45-80 keV band, the corresponding average fluxes were 28.2+/-1.4 and 38.7+/-2.8 mCrab. The source was variable reaching in a maximum the flux levels 60 and 95 mCrab in the above bands.
The best fit position, R.A.= 17h09m48s, Dec.= -36o28'12'' (equinox 2000.0, error radius 2') keeps the source firm outside the error box of IGRJ17091-3624 (R.A.=17h09m06s, Dec.=-36o24'07'', error radius 0.8', ATEL #150, see also ATEL #149, #160).
We detected no signs of the source fading during the reported period. Our observations were interrupted due to the end of revolution but INTEGRAL will continue to observe this region after recovery.
We encourage follow-up observations of this source at all wavelengths.
|
2005-03-27 01:04:00
|
radio,optical,x-ray,gamma ray,transient,variables,request for observations
|
445
|
The RXTE/ASM reveals rebrightening of GROJ1655-40
|
Smith, D. A. (U. of Michigan)
|
The RXTE/ASM reveals rebrightening of GROJ1655-40.
The 1-day averaged x-ray intensity of GRO J1655-40 has been declining since its maximum of 1.70±0.02 Crab (2-12 keV) on 2005 Mar 19 (UT), reaching a minimum of 940±10 mCrab on Mar 26. On Mar 27, the average intensity was 960±10 mCrab. The average of the five 90-s observations taken on Mar 28 (at this writing) yield an average of 1.06±0.03 Crab, indicating that the source is rebrightening or possibly undergoing short-term flaring. The ASM hardness ratios for today are consistent with no change in color compared to the last two days.
The southern half of the ROTSE-III world-wide telescope system has been monitoring GROJ1655-40 since 2005 Mar 8.6. The features of the optical light curve do not match the features of the ASM X-ray light curve. The optical intensity peaks around Mar 23.657 at 14.10±0.05 magnitudes (ROTSE-III magnitudes are unfiltered, calibrated to the USNO A2.0 R-band catalog.). The source then fell by 0.6 mags over 1.1 days, before beginning to rise again. Our last measurement at Mar 28.095 yields an intensity of 14.14±0.05 mags. The source is clearly behaving differently at different wavelengths, and observations over a wide range of frequencies would be useful.
X-ray and optical light curves can be seen in this PDF file.
Thanks to the RXTE/ASM teams at MIT and NASA/GSFC. Also thanks to the members of the ROTSE collaboration at UNSW Sydney, Siding Spring Observatory, MPI-Heidelberg, and the HESS team in Namibia.
|
2005-03-29 02:04:00
|
optical,x-ray,binary,black hole,transient
|
446
|
An outburst of the accreting millisecond X-ray pulsar XTE J1751-305 detected with INTEGRAL
|
S. A. Grebenev (IKI, Moscow), S. V. Molkov (IKI, Moscow), R. A. Sunyaev (IKI, Moscow; MPA, Garching)
|
The X-ray transient XTE J1751-305 was detected in outburst with IBIS/ISGRI on March 28.054-28.464, 2005 (UT), during INTEGRAL deep Open Program observations of the Galactic center region. The average flux was equal to 20.4+/-1.2 and 16.8+/-2.8 mCrab in the 18-45 and 45-80 keV bands. No notable variabilty was found on a time scale of hours during this time interval. The source was not detected during our previous observations of the region on March 26.104-26.778.
XTE J1751-305 was discovered with RXTE on April 3, 2002, during the outburst lasted 12 days (IAUC # 7867 ). It is one of the four currently known accreting millisecond pulsars and the second of this kind to be found. It has a spin frequency of 435 Hz.
We encourage follow-up observations of this source at all wavelengths.
|
2005-03-29 02:51:00
|
x-ray,neutron star,pulsar,star,transient,request for observations
|
447
|
Spectral evolution of IGR J17098-3628 observed by INTEGRAL and RXTE
|
S. A. Grebenev (IKI, Moscow), S. V. Molkov (IKI, Moscow), M. G. Revnivtsev (IKI, Moscow; MPA, Garching), R. A. Sunyaev (IKI, Moscow; MPA, Garching)
|
Two next sets of INTEGRAL deep Galactic center field observations (on March 26.104-26.778 and 28.054-28.464, 2005 UT) showed that IGR J17098-3628 (ATEL #444) is strongly evolving in both brightness and spectral shape. The flux measured during these sets was equal to 57.1+/-1.5 and 40.1+/-2.5 mCrab in the 18-45 keV band and 55.4+/-3.1 and 16.6+/-4.6 mCrab in the 45-80 keV band. Comparison with the flux values given in ATEL #444 points on the steady softening of the source X-ray spectrum.
The spectra measured on March 24-25 and March 26 could be satisfactory described by a simple power law in the broad 18-200 keV band without any signs of a high energy cut-off. The photon index was equal to 1.81+/-0.09 and 2.20+/- 0.06, respectively. The spectrum measured on March 28 was significant only below 70 keV. Its approximation with a power law led to the photon index 3.00+/-0.25.
The light curves of IGR J17098-3628 obtained with ISGRI as well as the related X-ray image can be found at www-site: http://hea.iki.rssi.ru/~sergei/igrj17098-3628.html.
The RXTE carried out the cross-scanning of this region on March 29.179-29.227 (UT) and detected the source with the 3-20 keV flux of about 80 mCrab (we thank the RXTE team for organizing such a prompt observation). The best-fit position (R.A.=17h09m38, Decl.=-36o27'41'', epoch 2000.0, error radius 5' ) is generally consistent (2.1' off) with the ISGRI position reported in ATEL #444. The spectrum was complex consisting of a soft black body component with kT~1.0 keV and a hard power law tail with the photon index of about 2.5. The hydrogen column density did not exceed 10^22 cm^-2. Assuming that the source is located at the Galactic center distance (8 kpc) its broad band X-ray luminosity can be estimated to be ~2x10^37 erg/s.
The observed behaviour of IGR J17098-3628 indicates that it is a new reliable black hole candidate and a possible X-ray nova at the initial stage of its outburst (during the transition to the very high state).
We encourage further observations of this source at all wavelengths.
|
2005-03-30 06:51:00
|
radio,infra-red,optical,x-ray,black hole,nova,transient,request for observations
|
448
|
SN 2005ay - a type II SN to be observed by GALEX
|
Avishay Gal-Yam and Graham P. Smith (Caltech)
|
Avishay Gal-Yam and Graham P. Smith report on behalf of a larger collaboration, including the CCCP and the GALEX Core-collapse SN ToO teams: We observed SN 2005ay (Rich; IAUC# 8500 ) using the DBSP spectrograph mounted on the 200" Hale telescope at Palomar Observatory, starting on Mar 29.4 UT. A preliminary reduction of the spectrum reveals prominent H and He lines superposed on a blue continuum. This indicates a young type II event, consistent with the findings of Taubenberger et al. from March 29.9 UT (IAUC # 8502 ). The profile of the Halpha line is peculiar, and all the lines appear surprisingly strong for a young Type II SN (Yamaoka and Igataki, IAUC# 8502 ). The prompt classification of this SN at Palomar allowed us to trigger our GALEX Target of Opportunity program (P.I. Gal-Yam), which is designed to obtain a series of UV spectra for nearby, young and bright core-collapse SNe. Observations will commence on Saturday, Apr. 2, 2005. Such UV data have rarely been obtained for core-collapse SNe. Intensive observations of this event at all available wavelengths are therefore strongly encouraged. We thank the Palomar engineering staff, and our support astronomer Rick Burruss for their dedication and hard work - without their help the Palomar observations would not have been possible. We also acknowledge K. Forster and T. Conrow at the GALEX SOC for their help in facilitating the ToO observation.
|
2005-03-31 13:59:00
|
optical,ultra-violet,supernovae,request for observations
|
449
|
RXTE PCA Observations of XTE J1751-305
|
J. H. Swank (NASA/GSFC), C. B. Markwardt (U. Maryland & NASA/GSFC), E. A. Smith (L-3 Communications)
|
The RXTE PCA observed the position of XTE J1751-305 on Mar 28.812 (UTC) for about two minutes, on Mar 29.229-29.273, and on Mar 30.478-30.517, as well as in a scan on Mar 30.379. The PCA flux is systematically uncertain due to the contributions from diffuse galactic emission and other nearby sources in the PCA field of view. The uncertainty is about 3 mCrab peak-to-peak, based on the regular PCA bulge scans of the region.
For the longer observation on Mar 30, the 2-10 keV total flux is 2.8 mCrab, consistent with the best background flux estimated in the bulge scan analysis. There is a strong Fe line in the spectrum, which is another indicator of contamination by diffuse galactic emission. The bulge scan an Mar 30 also shows a background-subtracted flux of < ~1 mCrab.
Assuming that the background is fixed by the Mar 30 observation, then XTE J1751-305 was detected on Mar 28 at a level of about 7.7 mCrab (2-10 keV). The background subtracted spectrum is consistent with a power law of with photon index ~2. The net X-ray fluxes are 18.4, 8.3, and 8.2 x 10E-11 erg/cm^2/s in the 2-10, 10-20 and 20-40 keV bands, respectively. Because the Mar 28 observation was done by realtime command, the PCA instrument was not in the proper mode to detect pulsations.
The fluxes on Mar 29 were 9.1, 3.8, and 3.9 x 10E-11 erg/cm^2/s, in the corresponding energy bands. No pulsations were detected. The flux was about at the level where the pulses became undetectable as the April 2002 outburst decayed.
Based on these results, the flux appears to have decreased to the point of non-detectability by the PCA, since the hard X-ray measurement on Mar 28.054-28.464 by Grebenev et al. (ATEL #446).
|
2005-04-01 01:43:00
|
x-ray,binary,pulsar,transient
|
450
|
Aql X-1 optical/IR outburst
|
Dipankar Maitra and Charles Bailyn (Yale)
|
Ongoing SMARTS consortium observations of Aql X-1 with the 1.3m telescope at CTIO + ANDICAM instrument show evidence for a new outburst from this source. Data obtained starting 3/29/05 showed significant flux above the quiescent level - as of April 2.381 (UT) we find R=17.1 (quiescent brightness of ~18.8) and J=15.5 (quiescent brightness of ~16.4). We note that these measurements include light from the near neighbor star (Chevalier et al., 1999, A&A, 347,L51). It is likely that the source is still in the canonical low/hard state and a transition to high/soft state might occur soon. Multiwavelength observations of the source are encouraged. Attached is the OIR lightcurve.
|
2005-04-03 09:40:00
|
infra-red,optical,binary,neutron star,star,transient,request for observations
|
451
|
Type Determination for SN 2005az
|
The Nearby Supernova Factory: G. Aldering, B. C. Lee, S. Loken, P. Nugent, S. Perlmutter, R. Scalzo, R. C. Thomas, L. Wang (Lawrence Berkeley National Laboratory, Berkeley, CA), C. Bonnaud, E. Pecontal (Centre de Recherche Astronomique de Lyon), N. Blanc, S. Bongard, Y. Copin, E. Gangler, L. Sauge, G. Smadja (Institut de Physique Nucleaire de Lyon), R. Kessler (Kavli Institute for Cosmological Physics, Chicago, IL), P. Antilogus, G. Garavini, S. Gilles, R. Pain (Laboratoire de Physique Nucleaire et de Haute Energies de Paris), C. Baltay, D. Rabinowitz, A. Bauer (Yale)
|
The Nearby Supernova Factory reports that a spectrum (range 340-1000 nm) of SN 2005az (IAUC # 8503 ), obtained April 4.49 UT with the SuperNova Integral Field Spectrograph on the University of Hawaii 2.2-m telescope, shows it to be a Type Ib near peak brightness. Si II 635.5 nm is well developed and slightly stronger than the He I 587.6 nm line. Na I D lines are present due to both the host and our own galaxy suggesting some extinction along the line of sight to the supernova.
|
2005-04-05 02:10:00
|
optical,supernovae
|
452
|
INTEGRAL detected Aql X-1 in hard X-rays
|
S. A. Grebenev (IKI, Moscow), G. Belanger (SEA, Saclay), A. Bodaghee (ISDC, Versoix), N. Lund (DSRI, Copenhagen), W. Hermsen (SRON, Utrecht; UvA, Amsterdam), A. Parmar (ESA/ESTEC, Noordwijk), J.-P. Roques (CESR, Toulouse), M. Mas-Hesse (LAEFF, Madrid)
|
INTEGRAL observed the region near Aql X-1 on April 1.825-1.924, 2005 (UT) during the Galactic plane scan. The IBIS/ISGRI telescope detected the source at the flux level of 54+/-3 and 64+/-8 mCrab in the 18-45 and 45-80 keV bands, respectively. The source was as well detected in the standard 3-20 keV X-ray band with JEM-X at the flux level of about 35 mCrab. The combined spectrum can be well described with a single power law with a photon index of 1.98+/-0.06 in the broad 3-100 keV band.
Further observations will show if it is a temporal reactivation of the source in hard X-rays (a ``mini-outburst'' similar to that observed in March 2004) or the real beginning of a new X-ray outburst as was suspected by Maitra and Bailyn (ATEL #450) from their optical and infrared observations.
|
2005-04-06 00:04:00
|
radio,infra-red,optical,x-ray,neutron star,star,transient
|
453
|
INTEGRAL monitoring of IGR J17098-3628
|
N. Mowlavi (ISDC, Geneva), E. Kuulkers (ESA/ESAC, Spain), J. Rodriguez, S. Shaw (ISDC, Geneva), A. Paizis (ISDC Geneva/IASF Milano), T. Courvoisier (ISDC, Geneva), K. Ebisawa (NASA/GSFC, USA), P. Kretschmar (ESA/ESAC, Spain), C. Markwardt (NASA/GSFC, USA), T. Oosterbroek, A. Orr (ESA/ESTEC, Netherlands), R. Wijnands (UvA, Netherlands)
|
IGR J17098-3628 (ATEL #444) has been observed by INTEGRAL in the Galactic Bulge Monitoring program (ATEL #438). We detected the source with ISGRI in observations during 2005, March 26 00:00, April 2 02:45 and April 3 23:30 with fluxes of, respectively, ~50 mCrabs, ~12 mCrabs and ~9 mCrabs in 20-60 keV. The detection on April 3 is marginal due to slightly higher background compared to the previous observation. The detection significances were 22, 5.5 and 3.8 during the three periods, respectively. On March 26, the source was also detected in the 60-150 keV band at an intensity of ~50 mCrabs (IBIS/ISGRI). It was not detected, at these energies, on april 2 and 3, with an upper limit of 15 mCrabs. The source was not detected in either energy band in the Galactic Bulge Monitoring observations before March 25.
|
2005-04-06 00:35:00
|
radio,optical,x-ray,gamma ray,transient
|
454
|
Type Determination for SN 2005be
|
The Nearby Supernova Factory: G. Aldering, B. C. Lee, S. Loken, P. Nugent, S. Perlmutter, R. Scalzo, R. C. Thomas, L. Wang (Lawrence Berkeley National Laboratory, Berkeley, CA), C. Bonnaud, E. Pecontal (Centre de Recherche Astronomique de Lyon), N. Blanc, S. Bongard, Y. Copin, E. Gangler, L. Sauge, G. Smadja (Institut de Physique Nucleaire de Lyon), R. Kessler (Kavli Institute for Cosmological Physics, Chicago, IL), P. Antilogus, G. Garavini, S. Gilles, R. Pain (Laboratoire de Physique Nucleaire et de Haute Energies de Paris), C. Baltay, D. Rabinowitz, A. Bauer (Yale)
|
The Nearby Supernova Factory reports that a spectrum (range 340-1000 nm) of SN 2005be (IAUC # 8506 ), obtained April 6.49 UT with the SuperNova Integral Field Spectrograph on the University of Hawaii 2.2-m telescope, shows it to be a Type Ia about a week after maximum. It is quite similar to the spectrum of SN 1996X at that epoch [Salvo et al. (2001), through the SUSPECT database]. The supernova expansion velocity, derived from the minimum of Si II (rest 635.5 nm) and adopting the NED redshift of 0.03351 for the host, is 10,500 km/s.
|
2005-04-07 02:09:00
|
optical,supernovae
|
455
|
State transition of GX 339-4
|
D. M. Smith (University of California, Santa Cruz (UCSC)), Jeroen Homan (MIT), Nathan Bezayiff (UCSC)
|
Twice-weekly monitoring with the Proportional Counter Array (PCA) of the Rossi X-ray Timing Explorer shows that GX 339-4 is coming out of an extended period spent in the soft state. The most recent observation, made on 6 April 2005 from 18:03:00 to 18:20:00, shows spectral and timing characteristics of an intermediate state.
A disk blackbody component of best-fit maximum temperature (0.57 +/- 0.02) keV carries 2/3 of the energy from 2.5 to 25 keV, and a power law of best-fit photon index (2.21 +/- 0.09) carries most of the remainder. A broadened and redshifted iron fluorescence line (Gaussian center energy (5.4 +/- 0.2) keV, sigma = (1.3 +/- 0.2) keV) must also be included to achieve a good spectral fit.
The spectral changes have been gradual and subtle, but the power spectrum shows rapid and clear evolution over the last few pointings (see Table). The most recent observation is the first to show a quasi-periodic oscillation. The QPO, at (3.50 +/- 0.04 Hz), is strong, with integrated rms of (10.5 +/- 0.6)%, and well defined, with Q = (3.6 +/- 0.7).
Observation Number MJD % rms variability, 0.01-100 Hz 91105-04-06-00 53452.34758753 < 3.3 91105-04-08-00 53455.82666160 < 3.2 91105-04-07-00 53459.46703197 6.7 +/- 1.3 91105-04-09-00 53463.19425419 13.3 +/- 1.1 91105-04-10-00 53466.75369864 13.6 +/- 1.0
We note that the transition to the hard state seems to be occurring at approximately the same luminosity as during decline of the last outburst, in February 2003, lending further evidence to the idea that the soft-to-hard transition near the end of transient outbursts occurs at a nearly constant fraction of the Eddington luminosity (Maccarone 2003, A&A 409, 697), in strong contrast to the early hard-to-soft transition, which usually occurs near the peak luminosity of the outburst, whatever that peak happens to be. In the current case, the transition is accompanied by a small increase in luminosity, and it is possible that the current transition could represent the very beginning of a new rebrightening phase rather than the ordinary transition during decline. In either case, the system is certainly in a rare and short-lived state, and observations at all wavelengths are encouraged. Within two weeks, when the source is likely to become even harder, we expect an increase in the radio and IR brightness of GX 339-4.
The URL below links to figures showing 1) the evolution of the PCA count rate and hardness during the current outburst and 2) the QPO in the most recent observation.
|
2005-04-08 06:09:00
|
radio,x-ray,binary,black hole,transient,request for observations
|
456
|
Discovery of a new X-ray transient IGR J16283-4838 with INTEGRAL
|
S. Soldi (ISDC, Geneva), S. Brandt (DSRI, Copenhagen), A. Domingo Garau (LAEFF, Vilspa), S. A. Grebenev (IKI, Moscow), E. Kuulkers (ESA/ESAC, Spain), G. G.C. Palumbo (Bologna University), A. Tarana (IASF/Rome-INAF)
|
We report the discovery of a new source by the IBIS/ISGRI detector on board INTEGRAL. The new source, IGR J16283-4838, was detected during a core program observation of the Norma Arm between 2005 April 7 13:56:50 U.T. and April 9 04:44:23 U.T., with a flux of ~3.6 mCrab in the 20-60 keV band and a significance of 6.2 in a mosaic image of 126 ksec. The source was not detected in the 60-200 keV band. This is the first time that an INTEGRAL detection of this source is reported. An analysis of the ISGRI mosaic image of the previous observation of the same region, between 2005 April 4 01:55:25 and 2005 April 6 11:23:50, reveals a 4 sigma upper limit at ~1.7 mCrab, indicating that the source is rising in a timescale of days. Its position is RA=16:28.3, DEC=-48:38, with a 3' accuracy.
|
2005-04-11 23:16:00
|
x-ray,transient,request for observations
|
457
|
IGR J16493-4348 - a radiopulsar or a new X-ray binary
|
S. A. Grebenev (IKI, Moscow), A. J. Bird (Southampton University), S. V. Molkov (IKI, Moscow), S. Soldi (ISDC, Versoix), P. Kretschmar (ESA/ESAC, Vilspa), R. Diehl (MPE, Garhing), C. Budz-Joergensen (DSRI, Copenhagen), B. McBreen (UCD, Dublin)
|
During the Galactic plane survey carried out with INTEGRAL in 2004 a weak X-ray source was marginally (S/N=6.3) detected with IBIS/ISGRI at the position coincident with that of the 0.87 s radiopulsar PSR J1649-4349 (Bird et al., ApJ, 607, L33, 2004; Bassani et al. ATEL #232).
This source was recently detected again during the INTEGRAL deep survey of the Norma Arm region at the S/N ratio of 9.1 in the 18-45 keV band. The best fit position, R.A.=16h49m21s, Decl.=-43d48m36s (equinox 2000.0, uncertainty 2'), was only 45 arcsec off that of PSR J1649-4349. For the first time it became possible to measure with confidence the photon flux from this source 5.6+/-0.6 mCrab (averaged over the interval April 6.239-9.198, 2005 UT). Some signs of the variability were detected with a short (~1 h) increase in flux to 15-20 mCrab but this requires further analysis and observations. Assuming that the spectrum has a Crab-like shape we derive the source's 18-45 keV luminosity to be 2.2 x 10^{35} erg/s at a 5.6 kpc distance of PSR J1649-4349 (Manchester et al. MNRAS, 328, 17, 2001). This value exceeds by 5 orders of magnitude the rate of energy loss (2.6 x 10^{30} erg/s) due to the spin-down (Pdot = 4.4 x 10^{-17}) of a neutron star in this pulsar.
We conclude that either this pulsar is a member of a currently unrecognized binary system with a notable level of episodic accretion (accretion should be irregular to save a radiopulsar; taking into account the pulsar's large age ~3 x 10^8 years and the weakness of its magnetic field B~2 x10^{11} G the system could be at the stage of transition to LMXB) or, that is more probable, the pulsar is serendipitous for the detected source and we can report on a previously unknown X-ray binary IGR J16493-4348 discovered with INTEGRAL.
We encourage further observations of this interesting object at all wavelengths.
|
2005-04-12 22:52:00
|
radio,infra-red,optical,x-ray,binary,black hole,neutron star,pulsar,star,transient
|
458
|
IGR J16283-4838 X-ray flux is rising
|
A. Paizis (ISDC Geneva, IASF Milano), J. M. Miller (Harvard-Smithsonian CfA), S. Soldi (ISDC Geneva), N. Mowlavi (ISDC Geneva)
|
Starting on April 10th, 2005, 01:25:59 UTC, INTEGRAL performed a TOO observation of GRO J1655-40 (PI Miller). The newly discovered IGR J16283-4838 (ATEL #456) has been in the partially coded field of view of ISGRI during all this observation. IGR J16283-4838 is detected in IBIS/ISGRI with a significance of 11.6 in the 20-60 keV mosaic (96 ksec) with a flux of ~ 8.5 mCrab. This corresponds to an increase by about a factor 2 relative to the ~3.6 mCrab flux measured at the time of its first detection on 7-9 April 2005 (ATEL #456).
|
2005-04-13 22:10:00
|
x-ray,transient
|
459
|
Swift-XRT detection of IGR J16283-4838
|
J. A. Kennea, D. N. Burrows, J. A. Nousek, M. Chester, P. Roming (PSU), S. Barthelmy, N. Gehrels (GSFC), V. Beckmann (GSFC-UMBC), S. Soldi (ISDC)
|
We report the localization of the Integral-discovered X-ray transient IGR J16283-4838. IGR J16283-4838 was observed by Swift on April 13th at 14:01:56 UTC for 2.5ks as a Target of Opportunity observation. We have performed a preliminary analysis of the Swift-XRT data and have found a uncatalogued X-ray source at the following coordinates: RA(J2000): 16:28:10.7, Dec(J2000): -48:38:55. We estimate an uncertainty of about 5 arcseconds radius (90% containment). This position is 91 arcseconds from the INTEGRAL position reported in ATEL #456. The source is highly absorbed with no detected emission below 1.5 keV.
|
2005-04-14 01:59:00
|
x-ray,gamma ray,transient
|
460
|
Possible infra-red counterpart to IGR J16283-4838
|
Jerome Rodriguez (CEA Saclay & ISDC Versoix), Ada Paizis (ISDC Versoix & IASF Milano)
|
We report on 2-MASS archival data analyses of the field of IGR J16283-4838 (Atel #456, 458, 459). A clear source is detected in the 2-MASS All-Sky Quicklook image archive (with name 2MASS J16281083-4838560) in the K band at a position consistent with the X-ray position obtained with the SWIFT-XRT detector (Atel #459), while only lower limits are obtained in the J and H bands. The position of the source is R.A. = 16h 28m 10.83s, Decl. =-48deg 38' 56.1" (equinox 2000.0; nominal uncertainty about 0".11) which is about 1.7" from the best position returned from SWIFT-XRT.
|
2005-04-14 16:25:00
|
infra-red,optical,x-ray,gamma ray,binary,black hole,neutron star,pulsar,star,transient
|
461
|
Discovery of CV ROTSE3 J16134+012124.4
|
E. S. Rykoff (U. Mich.), R. Quimby (U. Texas.) on behalf of the ROTSE collaboration
|
Rapid analysis of ROTSE-III sky patrol fields reveals a new CV which we designate ROTSE3 J16134+012124.4. The object was first detected Apr. 13.37, 2005 by the ROTSE-IIIb telescope at McDonald Observatory, Texas, at an unfiltered magnitude of 17.5. Follow-up observations over the following 18 hours with ROTSE-IIIa (at Siding Spring Observatory, Australia) and ROTSE-IIIc (at the H.E.S.S. site in Namibia) show the transient fading over half a day to m_R=17.9 on Apr. 13.64. It remained around m_R=18 through our most recent observation on Apr. 14.07. The transient has a quiescent counterpart marginally detected in the USNO-B1.0 catalog at m_R~20.4. A spectrum (430-890 nm) obtained on Apr. 13.44 with the 9.2m Hobby*Eberly Telescope (+ Marcario Low-Resolution Spectrograph) by J. Caldwell and E. Terrazas shows a blue continuum with prominent H-alpha and H-beta emission. We therefore conclude this is a galactic CV. Further information including a light curve and spectrum can be found at http://www.rotse.net/transients/j1613/index.html .
|
2005-04-15 08:15:00
|
optical,cataclysmic variable,transient,variables
|
462
|
New X-ray outburst from Rapid Burster
|
S. V.Molkov (IKI, Moscow), S. A.Grebenev (IKI, Moscow),R. A.Sunyaev (IKI, Moscow;MPA, Garching)
|
We report the detection of an outburst from MXB1730-335 (Rapid Burster) with the INTEGRAL observatory during ultra deep observations of the Galactic Center field. In observations during Apr. 14 UT08:20 - Apr. 14 UT18:00, 2005 the source flux increased from undetectability (<2 mCrab) to 17+/-2 mCrab in the 18-60 keV energy band. The source was only marginally detected with JEM-X on the level of 15 mCrab in the energy range 3-20 keV. No bursting activity was observed.
Practically continuous observations of this region of the sky with INTEGRAL are scheduled through Apr. 21, 2005.
|
2005-04-15 16:04:00
|
x-ray,gamma ray,binary,globular cluster,transient
|
463
|
IGR J17303-0601 is a new intermediate polar
|
B. T. Gaensicke (Warwick), T. R. Marsh (Warwick), A. Edge (Durham), P. Rodriguez-Gil (IAC), D. Steeghs (CfA), S. Araujo-Betancor (STScI), E. Harlaftis (NO Athens), O. Giannakis (NO Athens), S. Pyrzas (Thessaloniki), L. Morales-Rueda (Nijmegen), A. Aungwerojwit (Warwick)
|
We have identified IGR J17303-0601 (1RXS J173021.5-055933) as an intermediate polar (IP). The optical counterpart is USNOA2.0 0825_10606993 (RA=17h30m21.9s Dec=-05d59m31s). Using optical photometry obtained in 2003 at the JKT and at the OGS we determine the white dwarf spin period to be 120s, which is the second-shortest spin period discovered so far (after AE Aqr, Pspin=33s). The spin folded light curve has a double-pulse structure, suggesting that both accreting poles / accretion curtains contribute to the optical light. Time-resolved spectroscopy obtained using the Calar Alto 2.m, the INT, the WHT, and the Magellan-Clay telescope show a radial velocity variation of 925.27min which we interpret as the orbital period of the system. It may be that IGR J17303-0601 is in a similar evolutionary state as AE Aqr, i.e. a post thermal-timescale mass transfer system (Schenker et al. 2002, MNRAS 337, 1105), and we encourage additional follow-up observations probing for radio / optical flares, as well as monitoring the spin period for a period change. The list of 123 IBIS/ISGRI sources from the galactic plane survey (Bird et al. 2004, ApJ Letters 607, 33) contains 6 confirmed cataclysmic variables, of which 4 IPs (including the IGR J17303-0601), one dwarf nova and one polar. It appears that at low galactic latitudes the combination of large X-ray luminosities and hard spectra makes IPs the predominant CV subtype picked up by INTEGRAL, and follow-up observations of unidentified INTEGRAL sources may well lead to the discovery of additional IPs.
|
2005-04-15 16:24:00
|
radio,optical,x-ray,binary,cataclysmic variable,nova,variables
|
464
|
Significant increase of the X-ray flux and slight softening of the spectrum of Aql X-1
|
Jerome Rodriguez (CEA Saclay & ISDC Versoix), Ada Paizis (ISDC Versoix & IASF Milano), Marion Cadolle-Bel (CEA Saclay), Diana C. Hannikainen (Observatory of Helsinki) & Simon E. Shaw (Univ. Southampton & ISDC Versoix)
|
On April 12th, 2005, 20:49:01 UTC, INTEGRAL performed an observation of GRS 1915+105 as part of a monitoring campaign of this microquasar. During this observation, Aql X-1 has always been in the IBIS/ISGRI partially coded field of view. The IBIS/ISGRI telescope detected the source at a flux level of 141+-1 mCrab in the 18-45 keV band and 101+-3 mCrab in the 45-80 keV energy range (average values over a ~100 ksec observation, assuming a crab-like spectrum). This shows the source fluxes have increased significantly with respect to the values reported by Grebenev et al. ~10 days earlier (54+/-3 mCrab in 18-45 keV, and 64+/-8 mCrab in 45-80 keV, see ATEL #452).
|
2005-04-15 18:41:00
|
x-ray,gamma ray,binary,black hole,neutron star,pulsar,star,transient
|
465
|
RXTE Observations of IGR J16283-4838 and IGR J16493-4348
|
C. B. Markwardt (U. Maryland & NASA/GSFC), J. H. Swank, E. Smith (NASA/GSFC)
|
RXTE has observed two recently reported INTEGRAL transients, IGR J16493-4348 and IGR J16283-4838.
IGR J16493-4348 was reported to be associated with the pulsar PSR J1649-4349 (Grebenev et al, ATEL #457). RXTE observed on Apr 14 at 02:20 for 3.5 ks, and on Apr 15 at 14:33 for 2.6 ks. Because of the Proportional Counter Array's (PCA) large field of view (2 deg at FWZM), the count rates are contaminated by significant amounts of galactic emission. On April 14, the count rate was variable on time scales of 100 to 1000 seconds; on April 15, the count rate was lower and flat. Assuming the second observation approximately represents quiescence, the variations on April 14 are from 0 to 3.6 ct/s/PCU (2-10 keV). No significant pulsations are detected from IGR J1649-4348 at any period, including the 0.871 second pulse period of PSR J1649-4349 (Manchester et all, 2001, MNRAS, 328, 17).
The background subtracted mean spectrum of IGR J16493-4348 is consistent with a heavily absorbed power law (with n_H of ~1 x 10E23 cmE-2 and photon index 1.4). The fluxes in the 2-10, 10-20 and 20-40 keV bands are 1.0, 1.3 and 2.1 (units of 10E-11 erg cmE-2 sE-1). No significant line emission is required.
IGR J16283-4838 was reported as a rising X-ray transient (ATEL #456, #458), was localized by the Swift XRT (ATEL #459), and may have an IR counterpart (ATEL #460). RXTE observed on April 14 at 00:46 for 3.6 ks, and on April 15 at 16:07 for 2.9 ks. Like J16493, J16283 is contaminated by galactic emission. Taking a best estimate of the background, the source is again well modeled by an absorbed power law (with n_H of ~4-5 x 10E22 and photon index 0.8 - 1.1). On April 14 the fluxes in the 2-10, 10-20 and 20-40 keV bands were 7.6, 11 and 21 (units of 10E-11 erg cmE-2 sE-1). On April 15, the fluxes were 3.8, 7.0 and 16 (same bands and units). No pulsations were detected.
The highly absorbed spectrum of J16283 is consistent with that reported by Kennea et al (ATEL #459). It appears that both sources have declined significantly since the last INTEGRAL reports. However if an imaging instrument observes J16493, it too should have a highly absorbed spectrum.
|
2005-04-17 05:36:00
|
x-ray,black hole,neutron star,pulsar,star,transient,variables
|
466
|
Type Determination for SN 2005bp
|
The Nearby Supernova Factory: G. Aldering, B. C. Lee, S. Loken, P. Nugent, S. Perlmutter, R. Scalzo, R. C. Thomas, L. Wang (Lawrence Berkeley National Laboratory, Berkeley, CA), C. Bonnaud, E. Pecontal (Centre de Recherche Astronomique de Lyon), N. Blanc, S. Bongard, Y. Copin, E. Gangler, L. Sauge, G. Smadja (Institut de Physique Nucleaire de Lyon), R. Kessler (Kavli Institute for Cosmological Physics, Chicago, IL), P. Antilogus, G. Garavini, S. Gilles, R. Pain (Laboratoire de Physique Nucleaire et de Haute Energies de Paris), C. Baltay, D. Rabinowitz, A. Bauer (Yale)
|
The Nearby Supernova Factory reports that a spectrum (range 340-1000 nm) of SN 2005bp (IAUC # 8515 ), obtained April 19.5 UT with the SuperNova Integral Field Spectrograph on the University of Hawaii 2.2-m telescope, shows it to be a Type II shortly after explosion. Weak P-Cyg profiles of H_alpha and He I 587.6-nm are present at a velocity of approximately 17,000 km/s, assuming the NED velocity for the host of 8288 km/s.
|
2005-04-20 05:34:00
|
optical,supernovae
|
467
|
New X-ray transient IGR J17473-2721 discovered with INTEGRAL
|
S. A. Grebenev (IKI, Moscow), S. V. Molkov (IKI, Moscow), R. A. Sunyaev (IKI, Moscow; MPA, Garching)
|
We report the discovery with the IBIS/ISGRI telescope on board INTEGRAL of a previously unknown hard X-ray source IGR J17473-2721. The source was detected during ultra deep Open Program observations of the Galactic center field carried out on March 17-28 and April 9-21, 2005. The signal-to-noise ratio for this source at the mosaic image was S/N=16.9 in the 18-45 keV band and S/N=5.6 in the 45-80 keV band. The average flux was equal to 3.87+/-0.23 and 2.8+/-0.5 mCrab in the same bands. The source best-fit position was found to be R.A.=17h47m21s, Decl.=-27d21m29s (equinox 2000.0, uncertainty 2').
The source was also detected during individual revolutions (on a time scale of 3 days) with the S/N ratio ranging from 4-6 in the middle of March to 8-10 in the middle of April. Such behaviour indicates steady brightening of the source with the increase of its 18-45 keV flux from 2.7 to 5.6 mCrab, respectively.
We encourage follow-up observations of this source at all wavelengths.
|
2005-04-23 00:51:00
|
radio,infra-red,optical,x-ray,black hole,neutron star,star,transient,request for observations
|
468
|
Start of OIR reflare in GX 339-4
|
Michelle Buxton, Charles Bailyn (Yale University)
|
Observations of GX 339-4 taken with the SMARTS 1.3m telescope at CTIO show that it has increased significantly at infrared wavelengths, indicating the beginning of an optical/infrared (OIR) reflare. The change in magnitudes between MJD 53476.3 and MJD 53482.3 are as follows: dV = 0.4, dI = 0.5, dJ = 0.8, dH = 1.0. We have observed this OIR reflare phenomenon during the 2002/2003 outburst of GX 339-4 (Buxton et al., in prep.) and in 4U 1543-47 (Buxton & Bailyn, 2004, ApJ, 615, 880) and XTE J1550-564 (Jain et al., 2001, ApJ, 554, L181). In each case, the reflares appeared after a transition into the low-hard state. Hence, these OIR reflares seem to be a common occurrence in BH LMXBs after transitioning into the low-hard state, as GX 339-4 did very recently (ATEL #455). It is widely believed that this X-ray state is associated with the presence of steady radio jets (Fender, Belloni & Gallo, 2004, MNRAS, 355, 1105). Therefore, these OIR reflares may be associated with synchrotron emission from a jet. We strongly encourage observers to monitor GX 339-4 at all wavelengths, particularly radio at more than one frequency, during this OIR reflare period. For our V- and J-band lightcurves see http://www.astro.yale.edu/buxton/smarts/light_curves/gx339.html.
|
2005-04-23 00:53:00
|
radio,infra-red,optical,x-ray,binary,black hole,transient
|
469
|
IGR J11215-5952 discovered in INTEGRAL Galactic Plane Scans
|
P. Lubinski (CAMK, Warsaw & ISDC), M. Gadolle Bel (CEA, Saclay), A. von Kienlin (MPE, Munich ), C. Budtz-Jorgensen (DSRI, Copenhagen), B. McBreen (Univ. College Dublin), P. Kretschmar (ESA/ESAC, Spain), W. Hermsen (SRON-Utrecht), P. Shtykovsky(SRI, Moscow)
|
We report the discovery of a new source of hard X-rays by the IBIS/ISGRI detector on board INTEGRAL. The new source, IGR J11215-5952, was detected in the 20--60 keV band in two consecutive core programme observations of Galactic Plane Survey, each of ~ 2100 second duration. The approximate 20--60 keV count-rate and mCrab equivalents, for pointings starting at the given times, are as follows:
The position of the source is: RA=11h21m45s, DEC=-59d52' with 3' accuracy. The new source is located about 45' from Cen X-3.
During this Galactic Plane scan, the only pointings of the new source region are the two given above and the source region is not scheduled to be observed with INTEGRAL until 15th May.
The source was not detected in the 60-200 keV ISGRI images, suggesting a soft spectrum. This could not be confirmed by JEM-X, which did not detect the new source in the 3--10 keV or 10--30 keV bands. However, it should be noted that the source position was only in the field of view of JEM-X in one pointing (starting at 06:43:01), when it was located approximately 3.5 degrees from the pointing direction, where systematic effects start to limit the sensitivity of the JEM-X instrument.
Follow-up observations are encouraged.
|
2005-04-23 01:27:00
|
x-ray,gamma ray,transient,request for observations
|
470
|
HD 306414 and IGR J11215-5952
|
Ignacio Negueruela (Alicante), David M. Smith (U. C. Santa Cruz), Sylvain Chaty (CEA/Saclay)
|
We note that the B supergiant HD 306414 (Tycho coordinates RA: 11 21 46.807, Dec: -59 51 47.93) lies only 16" away from the nominal position for the new INTEGRAL transient IGR J11215-5952 (ATel #469).
From 2MASS and USNO-B1 archival data analyses, HD 306414 is the brightest optical object in the 3' error circle, though there are three brighter IR sources, namely 2MASS J11214129-5953035 (K=7.15, b=15.3), 2MASS J11220105-5950185 (K=6.10, b=12.8) and 2MASS J11220165-5952502 (K=8.05, b=19.2). For HD 306414, 2MASS lists J=8.55, H=8.34, K=8.19.
Accurate optical photometry for HD 306414 is provided by Klare & Neckel (1977, A&AS 27, 215), who quote V=9.98, (B-V)=0.59, (U-B)=-0.45. Drilling (1991, ApJS 76, 1033) measures UBV values fully consistent within the expected errors. Vijapurkar & Drilling (1993, ApJS 89, 293) derive a spectral type B1Ia for HD 306414. The reddening to HD 306414 is, hence, moderate E(B-V)=0.78. If the luminosity class is correct and the reddening law is standard (Av=2.42), the distance to the supergiant is around 8 kpc.
Obviously only a better position for IGR J11215-5952 can confirm or discard the association with HD 306414. However, taking into account the accuracy of previous INTEGRAL nominal positions and the nature of most of the new INTEGRAL sources (e.g., Lutovinov et al. astro-ph/0411550 or ATel #429), the identity is very likely
|
2005-04-23 17:38:00
|
infra-red,optical,x-ray,binary,transient,a comment
|
471
|
Type Determination for SN 2005bt
|
The Nearby Supernova Factory: P. Antilogus, G. Garavini, S. Gilles, R. Pain (Laboratoire de Physique Nucleaire et de Haute Energies de Paris), G. Aldering, B. C. Lee, S. Loken, P. Nugent, S. Perlmutter, R. Scalzo, R. C. Thomas, L. Wang (Lawrence Berkeley National Laboratory, Berkeley, CA), C. Bonnaud, E. Pecontal (Centre de Recherche Astronomique de Lyon), N. Blanc, S. Bongard, Y. Copin, E. Gangler, L. Sauge, G. Smadja (Institut de Physique Nucleaire de Lyon), R. Kessler (Kavli Institute for Cosmological Physics, Chicago, IL), C. Baltay, D. Rabinowitz, A. Bauer (Yale)
|
The Nearby Supernova Factory reports that a spectrum (range 340-1000 nm) of SN 2005bt (IAUC # 8518 ), obtained April 24.5 UT with the SuperNova Integral Field Spectrograph on the University of Hawaii 2.2-m telescope, shows it to be a Type II with well developed hydrogen features as well as He I 587.6 nm. Assuming the NED velocity for the host, H-alpha has an expansion velocity of 6800 km/s.
|
2005-04-26 14:13:00
|
optical,supernovae
|
472
|
Hard X-ray brightening of Ginga 1843+009 seen by INTEGRAL
|
J.-C. Leyder (ISDC, Geneva & IAG Liege), J. Chenevez (DSRI, Copenhagen), M. T. Fiocchi (IASF/Rome-INAF), M. Revnivtsev (IKI, Moscow & MPA, Garching), J. Paul (CEN--Saclay), T. Oosterbroek (ESA/ESTEC), M. Mas-Hesse (LAEFF, Madrid), A. Strong (MPI, Garching)
|
The transient X-ray pulsar, Ginga 1843+009, appears to be undergoing a hard X-ray outburst brighter than the one reported in May 2003 (ATEL #159).
The source has been observed during ISWT observations of the Scutum Arm region with INTEGRAL and was first detected when the source was in the field of view of the ISGRI imager on 2005-04-23T11:05 with a 20-60 keV count rate of ~3 cps, corresponding to ~20 mCrab. This is the first time this source has been detected in a single ~2000s pointing with ISGRI, and is approximately the same level as the flux reported in ATEL #159.
Over the following ~5 days, the source appears to have slowly doubled in brightness, to its current level of ~6 cps (40 mCrab).
The source was also visible in JEM-X images in a single pointing at 2005-04-29T04:42 with fluxes of approximately 15 and 20 mCrab, in the 3-10 and 10-30 keV bands respectively. During this pointing the corresponding 20-60 keV ISGRI flux was ~30 mCrab, indicating a spectrum which is harder than the Crab.
Observations at other wavelengths are encouraged.
|
2005-04-29 23:04:00
|
x-ray,gamma ray,pulsar,transient
|
473
|
Type Determination for SN in UGC 8539
|
The Nearby Supernova Factory: N. Blanc, S. Bongard, Y. Copin, E. Gangler, L. Sauge, G. Smadja (Institut de Physique Nucleaire de Lyon), P. Antilogus, G. Garavini, S. Gilles, R. Pain (Laboratoire de Physique Nucleaire et de Haute Energies de Paris), G. Aldering, B. C. Lee, S. Loken, P. Nugent, S. Perlmutter, R. Scalzo, R. C. Thomas, L. Wang (Lawrence Berkeley National Laboratory, Berkeley, CA), C. Bonnaud, E. Pecontal (Centre de Recherche Astronomique de Lyon), R. Kessler (Kavli Institute for Cosmological Physics, Chicago, IL), C. Baltay, D. Rabinowitz, A. Bauer (Yale)
|
The Nearby Supernova Factory reports that a spectrum (range 340-1000 nm) of the SN in UGC 8539 (Tim Puckett, private communication), obtained April 29.5 UT with the SuperNova Integral Field Spectrograph on the University of Hawaii 2.2-m telescope, shows it to be an early Type II at the redshift of the host galaxy. Present in this blue spectrum are the Hydrogen features H-alpha through H-delta as well as He I 587.6 nm.
|
2005-04-30 00:59:00
|
optical,supernovae
|
474
|
Type Determination for SN 2005bx
|
The Nearby Supernova Factory: C. Bonnaud, E. Pecontal (Centre de Recherche Astronomique de Lyon), N. Blanc, S. Bongard, Y. Copin, E. Gangler, L. Sauge, G. Smadja (Institut de Physique Nucleaire de Lyon), P. Antilogus, G. Garavini, S. Gilles, R. Pain (Laboratoire de Physique Nucleaire et de Haute Energies de Paris), G. Aldering, B. C. Lee, S. Loken, P. Nugent, S. Perlmutter, R. Scalzo, R. C. Thomas, L. Wang (Lawrence Berkeley National Laboratory, Berkeley, CA), R. Kessler (Kavli Institute for Cosmological Physics, Chicago, IL), C. Baltay, D. Rabinowitz, A. Bauer (Yale)
|
The Nearby Supernova Factory reports that a spectrum (range 340-1000 nm) of SN 2005bx (CBET #148), obtained May 1.5 UT with the SuperNova Integral Field Spectrograph on the University of Hawaii 2.2-m telescope, shows it to be a Type IIn. Assuming the NED velocity for the host of 9359 km/s, H-alpha appears in emission with a fwhm of approximately 3500 km/s.
|
2005-05-02 00:06:00
|
optical,supernovae
|
475
|
Type confirmation of SN 2005bx
|
A. Gal-Yam, D. J. Sand, S. B. Cenko, D. C. Leonard and J. Muller (Caltech/Palomar Observatory)
|
A. Gal-Yam, D. J. Sand, S. B. Cenko, D. C. Leonard, and J. Muller report on behalf of the CCCP that a preliminarily reduced spectrum (range 4000 - 9500 A) of SN 2005bx (Rich et al., CBET # 148) obtained using the double spectrograph mounted on the Palomar Observatory 200" Hale telescope, on Apr. 30, 2005, UT, shows this is a type IIn SN, similar to SN 1988Z (e.g., Filippenko 1997). This confirms an earlier report by the Nearby Supernova Factory (ATEL #474). Narrow Balmer emission lines with broad bases are superposed on a blue continuum.
|
2005-05-03 02:49:00
|
optical,supernovae
|
476
|
Swift-XRT detection of IGR J17098-3626
|
J. A. Kennea, D. N. Burrows, J. A. Nousek, M. Chester (PSU), S. Barthelmy, N. Gehrels (GSFC), S. Grebenev (IKI-Moscow), V. Beckmann (GSFC-UMBC)
|
We report the localization of the Integral-discovered X-ray transient IGR J17098-3626 (ATEL #444). IGR J17098-3626 was observed by Swift on May 1st from 16:23 UTC until 18:19 UTC with an exposure time of 2.8ks. The source was predicted to be bright, so the XRT was put into Photon Counting mode for 500s of the observation in order to obtain a position, with the remainder of the observation taken in Window Timing mode.
We have performed a preliminary analysis of the Swift-XRT data and have found a uncatalogued X-ray source at the following coordinates: RA(J2000): 17:09:45.9 Dec(J2000): -36:27:57. We estimate an uncertainty of about 5 arcseconds radius (90% containment). This position is 30 arcseconds from the INTEGRAL position reported in ATEL #444.
The source is bright, with the Photon Counting mode data showing significant pile-up. We estimate an average source flux from Window Timing data of 1.3 x 10^-9 erg/s/cm^2 (0.5-10 keV) with an absorption of approximately 10^22 cm^-2, which is consistent with Galactic absorption. The source appears to be fading, with the flux dropping by ~8% over the duration of the observation.
|
2005-05-03 03:03:00
|
x-ray,gamma ray,transient
|
477
|
Possible infrared/optical counterpart of IGR J17098-3628
|
A. K.H. Kong (MIT)
|
Following the soft X-ray detection of the X-ray transient IGR J17098-3628 with Swift-XRT, we search for infrared/optical counterpart with the 2MASS All-Sky Catalog and the SuperCOSMOS Sky Survey. We note that there is a single star within the 5" radius error circle of the Swift-XRT (ATEL #476). The infrared counterpart, 2MASS J17094612-3627573 (J=14.69, H=13.66, and K=13.37), is about 2.7" from the X-ray position. From the SuperCOSMOS Sky Survey, a star with B=21.16, R=19.43, and I=18.75 is found at R.A.=17h9m46.166s and Decl.=-36d27m57.50s, 3.25" from the X-ray position.
More observations are strongly encouraged to confirm the counterpart.
|
2005-05-03 08:46:00
|
infra-red,optical,x-ray,binary,star,transient
|
478
|
Optical/NIR imaging of IGR J17098-3628 and IGR J16283-4838
|
D. Steeghs (CfA), M. A.P. Torres (CfA), P. G.Jonker (SRON/CfA), J. Miller (CfA), P. Green (CfA), C. Rakowski (CfA)
|
We report on optical and infrared observations acquired with the 6.5m Magellan-Baade telescope of the fields containing the INTEGRAL transients IGR J17098-3628 (ATEL#444) and IGR J16283-4838 (ATEL#456) for which SWIFT localizations have been reported (ATEL#476,#459).
IGR J17098-3628: optical I-band images of the field were obtained using the IMACS imaging spectrograph on 2005 April 9 9:40-9:50 UT. Seeing was 0.8" sampled at 0.2" per pixel with the 8Kx8K CCD mosaic. The images were tied to the 2MASS astrometric frame and revealed a large number of sources within the 5" SWIFT error circle reported in ATEL#476. Our images indicate that the counterpart candidate reported by Kong in ATEL#477 is actually a blend containing several sources within a few arcseconds. A comparison between the SuperCOSMOS sky survey image and our 360s IMACS image is available at: http://hea-www.cfa.harvard.edu/~dsteeghs/IGRJ17098-3628.jpg (SWIFT error circle plotted in red).
IGR J16283-4838: K band images were acquired on 2005 April 21 02:58-03:11 UT using the PANIC camera. The frames were obtained with a seeing of 0.7 arcsec and a projected pixel size of 0.125 arcsec on the 1024x1024 Hawaii detector. The images were tied to the 2MASS astrometric frame and show again a group of point sources within the SWIFT error circle (ATEL#459). We remark that the 2MASS candidate reported in ATEL#460 is a blend of point sources. Preliminary relative photometry with respect to four 2MASS nearby stars yields K~14.1 for the brightest source resolved in our images, consistent with the K=14 2MASS source. A comparison between the 2MASS field and our 300s PANIC K-band image is available at: http://hea-www.cfa.harvard.edu/~dsteeghs/IGRJ16283-4838.jpg (SWIFT error circle in red).
We plan to acquire additional imaging of these fields to identify the correct optical/NIR counterparts through their variability.
We caution that given the stellar densities in these low Galactic latitude fields, the chance of finding a non-related field star within a SWIFT X-ray error box is considerable (see linked images), even when using relatively shallow surveys such as DSS and 2MASS. Deeper imaging (to counter any significant reddening) with good spatial resolution at several epochs is crucial to separate the many field stars from the true and time-variable counterpart.
|
2005-05-04 04:53:00
|
infra-red,optical,x-ray,binary,black hole,neutron star,star,transient,variables
|
479
|
Possible Swift-UVOT optical counterpart for IGR J17098-3628
|
A. J. Blustin (MSSL-UCL), A. K. H. Kong (MIT), K. Wu, C. Brocksopp, K. McGowan (MSSL-UCL), J. A. Kennea, P. Roming, J. A. Nousek (PSU), K. O. Mason (MSSL-UCL), N. Gehrels (GSFC) on behalf of the Swift-UVOT team
|
The X-ray transient IGR J17098-3628, discovered by INTEGRAL (ATEL #444), was observed by Swift on May 1st from 16:23 UTC until 18:19 UTC. It was detected in soft X-rays by the Swift-XRT (ATEL #476), and possible optical/IR counterparts, associated with 2MASS J17094612-3627573, have been identified from the 2MASS All-Sky Catalogue, SuperCOSMOS Sky Survey (ATEL #477) and new observations with the Magellan-Baade telescope (ATEL #478).
During the May 1st Swift observation, the UV/Optical telescope (UVOT) obtained a total of 2443 s exposure time through the V filter. In an image generated from all of these data coadded, we detect a 19.3 +/- 0.1 magnitude source within the 5 arcsecond XRT error circle at R.A.=17h09m46.161s, Decl.=-36d27m58.05s, apparently identical with the possible SuperCOSMOS optical candidate at R.A.=17h9m46.166s and Decl.=-36d27m57.50s.
An image of the Swift-UVOT source is available at http://www.mssl.ucl.ac.uk/twiki/bin/view/SwiftBA/IGRJ17098-3628 .
As reported in the SuperCOSMOS Sky Survey, the B and R magnitudes of this source (or group of sources combined, as reported in ATEL #478) are 21.16 and 19.43 respectively. The observed UVOT V magnitude of 19.3 may imply that the optical transient has brightened; further observations are recommended to establish whether this is the case.
The Swift-UVOT magnitude is based on a preliminary zero-point, measured in orbit, and will require refinement with further calibration.
|
2005-05-04 05:45:00
|
infra-red,optical,x-ray,binary,black hole,neutron star,star,transient
|
480
|
Type determination of SN 2005by
|
Avishay Gal-Yam and George Djorgovski (Caltech)
|
Avishay Gal-Yam and George Djorgovski report that a spectrum obtained by Djorgovski with the DBSP spectrograph mounted on the Hale 200" telescope at Palomar Observatory, on May 4 2005 UT, shows this event is a young type II SN. Prominent broad Halpha with a P-cygni profile is superposed on a blue continuum.
|
2005-05-05 02:29:00
|
optical,supernovae
|
481
|
SDSS J124819.36+072049.4 is a Dwarf Nova
|
R. Quimby, M. Sellers, P. Mondol, P. Hoeflich, J. C. Wheeler (University of Texas), and C. Gerardy (Imperial College)
|
We report the discovery of a dwarf nova in unfiltered CCD images taken on Apr 26.25 UT (about 16.7 mag) and Apr 28.20 (about 17.0 mag) using the 0.45m ROTSE-IIIb telescope at the McDonald Observatory. The object is located at RA = 12h48m19.38s DEC = +07o20'48.8" and was not detected in ROTSE-IIIb data from Apr 20.20 UT (limiting mag about 17.0). The object was observed by the Sloan Digital Sky Survey in quiescence (SDSS J124819.36+072049.4) at r'=21.50 mag. A spectrum (420-890 nm) of the object obtained on Apr 29.13 with the 9.2m Hobby*Eberly Telescope (+ Marcario Low-Resolution Spectrograph) by S. C. Odewahn and M. Villarreal, shows doubly peaked H-alpha emission, along with absorption lines from H-beta, H-gamma, HeI 447.1 nm and 587.6 nm, and NaI 589 nm. ROTSE-IIIb data shows the object faded to about 17.7 magnitude on May 1.14 UT.
|
2005-05-06 01:14:00
|
optical,cataclysmic variable,nova,transient,variables
|
482
|
Superburst in 4U1608-52
|
R. Remillard and E. Morgan (MIT Kavli Institute for Astrophysics and Space Research) for the ASM team at MIT and NASA/GSFC
|
The light curve of "x1608-522" from the RXTE All-Sky Monitor on 2005 May 5 reveals a likely superburst lasting many hours. The ASM flux (2-12 keV) had been roughly steady during the last few days, ending with the measurement of 0.34 (03) Crab on MJD 53495.03995. The next measurement shows an abrupt increase to 1.25 (0.03) Crab on MJD 53495.10365, increasing to 1.50 (04) Crab on 53495.10476. Thereafter, the flux decays on a slower timescale, reaching 0.60 Crab at MJD 53495.62. The temporal profile and timescales of this event are strikingly similar to superbursts seen in other sources (see Kuulkers et al. 2002, A&A, 382, 503, and Strohmayer & Bildsten astro-ph/0301544).
|
2005-05-06 01:42:00
|
x-ray,neutron star,star
|
483
|
Probable superbursts in 4U 0614+091 and 4U 1608-522
|
Erik Kuulkers (ISOC, ESA/ESAC, Spain)
|
Inspection of the RXTE/ASM database of 4U 0614+091 reveals a recent flare which occurred on March 12, 2005. The 1.5-12 keV flux increased by a factor of 5-6 up to 0.3 Crab within ~7.5 hours. About 1.5 hours later the flux had dropped to 0.17 Crab; ~9.5 hours later it had reached the pre-flare flux level again. The exponential decay time of the flare is about 2.2 hours. During the peak of the flare the X-ray emission significantly hardens with respect to the pre- and post-flare level. These characteristics are similar to those reported for other hours-long thermonuclear X-ray events, so-called superbursts, seen in various other type I X-ray burst sources (see, e.g., Strohmayer & Bildsten astro-ph/0301544, and ATel #68, #482).
Note that the RXTE/ASM light curve of 4U 0614+091 shows more instances with flux values higher than about 0.25 Crab. Several of them, however, can be attributed to normal type I X-ray bursts in the field of view of the RXTE/ASM camera's, possibly from 4U 0614+091. It is interesting to comment that 4U 0614+091 only sporadically shows normal type I X-ray bursts (Swank et al. 1978, MNRAS 182, 349; Brandt et al. 1992, A&A 262, L15), i.e., unlike the other superburst sources, which possibly constrains superburst modeling.
Further to the discovery of a likely superburst in 4U 1608-522 (ATel #482), one may add that at the peak of that event the X-ray emission is clearly harder than the persistent X-ray emission before and after the event. During the decay of the event the X-ray emission is seen to soften. This further strengthens the association of this event with a superburst.
|
2005-05-06 23:27:00
|
x-ray,binary,neutron star,star,a comment
|
484
|
X-ray Outburst of the blazar, 3C454.3
|
R. Remillard (MIT Kavli Institute for Astrophysics and Space Research) for the RXTE ASM team at MIT and NASA/GSFC
|
The X-ray light curve of the blazar 3C454.3 was processed from observations with the RXTE All-Sky Monitor, following the report by Balonek (VSNET Alert) of an optical outburst. An X-ray detection is evident when the results are examined on timescales of one week or longer. Over the recent time interval, MJD 53490.0 to 53501.5, the average flux (2-12 keV) is 10.8 (1.7) mCrab, implying that 3C454.3 is currently one of the brightest AGN in the X-ray sky. During the previous 10 days (MJD 53480.0 to 53490.0), the flux is 0.4 (1.9) mCrab. We assess the outburst spectrum to be moderately hard, i.e. harder than the spectrum of a typical Galactic transient, yet softer than a classical X-ray pulsar. Multifrequency observations are needed.
|
2005-05-11 23:21:00
|
optical,x-ray,agn,blazar,pulsar,quasar,transient
|
485
|
OIR decline in GRO J1655-40
|
Michelle Buxton, Charles Bailyn (Yale University)
|
We have been monitoring the black-hole X-ray transient GRO J1655-40 in optical and infrared bands since the beginning of the current outburst (ATEL #414, 418). Observations are made daily (when possible) with the SMARTS 1.3m telescope at CTIO using the ANDICAM instrument. For the past 40 days, GRO J1655-40 remained at a steady magnitude of B ~ 16.4, V ~ 15.1, I ~ 13.2, J ~ 11.9 and K ~ 11.1. However, recent data taken on MJD 53499.2, MJD 53500.2 indicate that GRO J1655-40 is starting to decline, with a drop in magnitude of dB ~ 0.8, dV ~ 0.7, dI ~ 0.7, dJ ~ 0.6 and dK ~ 0.5. Our latest light curves can be seen at : http://www.astro.yale.edu/buxton/smarts/light_curves/oir_gro.jpg
|
2005-05-11 23:29:00
|
infra-red,optical,x-ray,binary,black hole,transient
|
486
|
Multiwavelength evolution of GROJ1655-40
|
D. A. Smith (U. of Michigan)
|
ROTSE-III monitoring of GRO J1655-40 reveals that over the last 24 hours, the optical intensity of this source has declined significantly. For the last forty days, it has remained near an unfiltered magnitude of 14.2 (calibrated to the USNO A2.0 R-band catalog), but at MJD 53500.489 it dropped to 14.7±0.2, and since 53501.0, it has remained within 0.1 mags of 15.1.
Meanwhile, the ASM quicktime analysis reveals that the 2-12 keV X-ray intensity has been rapidly flaring between levels of 2.0±0.1 to 4.4±0.1 Crab over the same time interval (using the individual 90-s dwells). Examination of the three sub-bands indicate a hardening of the spectrum.
Thanks to the RXTE/ASM teams at MIT and NASA/GSFC. Also thanks to the members of the ROTSE collaboration at UNSW Sydney, Siding Spring Observatory, MPI-Heidelberg, and the HESS team in Namibia.
|
2005-05-11 23:47:00
|
optical,x-ray,black hole,transient
|
487
|
GRO J1655-40 enters a highly-variable, high-luminosity state
|
Jeroen Homan (MIT), Jon M. Miller (CfA), Rudy Wijnands (U. of Amsterdam), and Walter H. G. Lewin (MIT)
|
GRO J1655-40 enters a highly-variable, high-luminosity state Jeroen Homan (MIT), Jon M. Miller (CfA), Rudy Wijnands (U. of Amsterdam), and Walter H.G. Lewin (MIT) Recent RXTE observations of the black hole X-ray transient GRO J1655-40, which is currently in outburst (e.g. ATEL #414,#417,#418,#419,#432,#438), show that the source has entered a highly variable, high-luminosity state. During the past two months the source has been steadily increasing in luminosity, while remaining spectrally soft. On May 10 the unabsorbed 3-200 keV flux increased from 3.9e-8 (erg/s/cm^2) to 6.8e-8 (erg/s/cm^2), compared to 2.9e-8 (erg/s/cm^2) on May 9. This increase was accompanied by a strong hardening of the X-ray spectrum and an increase in the strength of the 0.01-100 Hz variability (from ~5% to ~11% rms). In addition to red noise, which has dominated the power spectrum for the past two months, peaked noise and a weak QPO were observed in the 2-20 Hz range in the latest observation (taken on May 10 18:26 UTC).
Spectral fits were made to three 3-200 keV spectra obtained on May 10, with phenomenological (absorbed) multicolor disk blackbody plus power-law continuum models. These continuum models give an increasing apparent disk color temperature (kT = 1.3-1.5 keV) and varying power-law index (Gamma = 2.7 --> 2.5 --> 2.7), compared to kT = 1.27 and Gamma = 3.3 on May 9. These parameters are typical of the "very high" aka "steep power-law" state in Galactic black holes. Deconvolving the spectra in this way, the implied luminosity of GRO J1655-40 on May 10 rose from 1.2e38 erg/s to 2.7e38 erg/s in the 0.5-200 keV band (for d = 3.2 kpc), or approximately one-third of the Eddington limit for a 6 Msun black hole. The simple models used did not provide formally acceptable fits; the spectra also show indications for ionized disk reflection.
Observations with the RXTE/ASM on May 10 and 11 show that the source varies between ~2 and ~4.5 Crab on a time scale of a few hours (see also ATEL #486). This sudden turn-on of such strong variability is similar to that seen during the first part of the 1996/1997 outburst of GRO J1655-40.
As the X-ray spectral hardness of the source is close to the value during the period in which the source was radio bright (ATEL #419,#425,#434,#437,#443), GRO J1655-40 may show renewed radio activity. The sudden state change has already led to a decrease in the optical/IR flux of the source (ATEL #485). Further observations of GRO J1655-40 in the radio and optical/IR are encouraged in this relatively rare state. Daily RXTE/PCA observations will continue and the most recent results from these observations can be found at: http://tahti.mit.edu/opensource/1655/
This web-page now also includes light curves, power spectra, and energy spectra for all individual observations.
|
2005-05-11 23:53:00
|
radio,optical,x-ray,binary,black hole,transient,variables,request for observations
|
488
|
Radio monitoring of the blasar 3C454.3
|
Trushkin S. A. ( SAO RAS), Harinov M. A., Michailov A. G. (IAA RAS)
|
In ATEL #484 R. Remillard annonced about the bright X-ray outburst of the blazar 3C454.3 in May 2005. We have monitored 3C454.3 during the last 6 mounths with the RATAN-600 (SAO RAS) radio telescope in 17 September 2004 and then with RT32 radio telescope (Institute of Applied Astronomy RAS) from December 2004 to April 2005. The RATAN data (17/09/2004 = MJD53265): Frequency Flux Error GHz Jy Jy 0.61 16.3 1.0 0.98 15.8 0.7 2.3 13.47 0.3 4.8 11.33 0.2 7.7 10.54 0.2 11.2 9.40 0.2 21.7 6.95 0.3 30.0 6.0 0.3 The RT32 data (errors are less 5 %): Frequency 28-29 09 20-21 09-10 18-19 26 11-12 GHz Dec04 Jan05 Jan05 Fev05 Feb05 Mar05 Apr05 2.3 - - - - - 13.03 12.58 8.45 8.97 10.05 10.51 9.81 8.59 10.44 10.20 Thus these radio data just before the X-ray flare of 3C454.3 could be compared with follow-up radio observations. We plan to observe 3C454.3 16-18 May with RT32. You can see 3C454.3 radio spectrum here .
|
2005-05-12 17:28:00
|
radio,millimeter,x-ray,agn,blazar,request for observations
|
489
|
Recent radio evolution of GRO J1655-40
|
M. P. Rupen (NRAO/GSFC), V. Dhawan, A. J. Mioduszewski (NRAO)
|
Very Large Array (VLA) observations of of the black-hole X-ray binary GRO J1655-40 show a slight increase in radio flux density corresponding to the recent change in X-ray and optical/IR state (ATEL #485, ATEL #486, ATEL #487). The following results were obtained at 4.86 GHz:
The full radio light curves are shown at http://www.aoc.nrao.edu/~mrupen/XRT/GRJ1655-40/grj1655-40.shtml . Further VLA observations are planned, with the next scheduled for 16may05.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
|
2005-05-12 22:26:00
|
radio,optical,x-ray,binary,black hole,transient
|
490
|
Probable radio counterpart to IGR J17098-3628
|
M. P. Rupen (NRAO/GSFC), A. J. Mioduszewski, V. Dhawan (NRAO)
|
Very Large Array (VLA) observations of IGR J17098-3628 (ATEL #444) were made on March 31st, April 5th, April 12th, and May 4th UT, all at 4.86 GHz. The first data set showed the only significant radio source within the 2 arcminute INTEGRAL error circle, located at (J2000)
The NRAO VLA Sky Survey (NVSS; Condon et al. 1998, AJ, 115, 1693) shows no radio source within the Swift error circle, with a nominal flux density at that location of 1.2 +/- 0.6 mJy/beam at 1.4 GHz on 17jan95.
Contour plots of the recent observations are available at
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
|
2005-05-12 23:53:00
|
radio,x-ray,binary,black hole,neutron star,star,transient
|
491
|
Radio observations of Aql X-1
|
M. P. Rupen (NRAO/GSFC), A. J. Mioduszewski, V. Dhawan (NRAO)
|
Observations with the Very Large Array (VLA) during the recent X-ray outburst of Aql X-1 (ATEL #450, ATEL #452, ATEL #464) give the following nominal flux densities at 4.86 GHz:
Further VLA observations are planned.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
|
2005-05-13 00:07:00
|
radio,x-ray,binary,neutron star,star,transient
|
492
|
Detection of the Progenitor of SN 2004et
|
W. Li and A. V. Filippenko (University of California, Berkeley); and S. D. Van Dyk (Spitzer Science Center, California Institute of Technology)
|
The site of the Type II SN 2004et in NGC 6946 has been imaged in the Hubble Space Telescope Snapshot program GO-10272 (PI: A. V. Filippenko) with the ACS/HRC on 2005 May 2 UT. A pair of CR-split images was taken with each of the F435W and F625W filters, for a total exposure time of 840 s and 360 s, respectively. SN 2004et is still bright, with F435W = 18.07 mag and F625W = 15.36 mag. Comparison of the ACS/HRC images with those obtained by the Canada-France-Hawaii Telescope (CFHT) and analyzed by W. Li, S. D. Van Dyk, A. V. Filippenko, & J.-C. Cuillandre (2005, PASP, 117, 121) confirms their identification of the progenitor of SN 2004et in the CFHT images. When the ACS/HRC F435W image is geometrically transformed to match the best-seeing CFHT images, the position of SN 2004et is consistent with the progenitor in the CFHT image to within 0.056" +/- 0.043". SN 2004et thus becomes one of the only a few core-collapse supernovae whose progenitors have been directly identified.
|
2005-05-13 11:44:00
|
optical,supernovae
|
493
|
Type Determination for SN 2005bz
|
The Nearby Supernova Factory: G. Aldering, B. C. Lee, S. Loken, P. Nugent, S. Perlmutter, R. Scalzo, R. C. Thomas, L. Wang (Lawrence Berkeley National Laboratory, Berkeley, CA), C. Bonnaud, E. Pecontal (Centre de Recherche Astronomique de Lyon), N. Blanc, S. Bongard, Y. Copin, E. Gangler, L. Sauge, G. Smadja (Institut de Physique Nucleaire de Lyon), R. Kessler (Kavli Institute for Cosmological Physics, Chicago, IL), P. Antilogus, G. Garavini, S. Gilles, R. Pain (Laboratoire de Physique Nucleaire et de Haute Energies de Paris), C. Baltay, D. Rabinowitz, A. Bauer (Yale)
|
The Nearby Supernova Factory reports that a spectrum (range 320-1000 nm) of SN 2005bz (IAUC # 8527 ), obtained May 14.6 UT with the Supernova Integral Field Spectrograph on the University of Hawaii 2.2-m telescope, shows it to be a Type IIP SN at least a month after explosion. A well-developed net-emission H-alpha profile is accompanied by P-Cygni profile H-beta and O I 777 nm. Assuming the NED recession velocity of the host UGC 11162 of 4624 km/s, the hydrogen absorption features are at 4000 km/s, while the O I feature is at 10,000 km/s.
|
2005-05-15 06:23:00
|
optical,supernovae
|
494
|
Optical counterpart to IGR J17098-3628
|
D. Steeghs (CfA), M. A.P. Torres (CfA), P. G.Jonker (SRON/CfA), H. Chen (MIT), P. Green (CfA), J. Miller (CfA), M. R.Garcia (CfA)
|
Following the recent report of a possible radio counterpart to the X-ray transient IGR J17098-3628 (ATEL #490), we re-investigated our Magellan I-band exposures obtained on 2005 April 9 UT (see ATEL #478). The frames show a point source located at R.A.(J2000)=17:09:45.93, DEC(J2000)= -36:27:58.2 in the 2MASS reference frame (0.2" uncertainty). This optical position is consistent within 2 sigma with that derived from the radio observations (ATEL #490).
We acquired additional I-band images with the 6.5m Magellan-Baade telescope during 2005 May 13 9:19-9:27 UT. The instrumental setup and exposure times were similar to those used in our previous observation (ATEL #478). The seeing was also comparable at 0.6 arcsec. Differential photometry with respect to 6 nearby stars indicates that the optical source close to the radio position has faded by 0.12 +/- 0.02 mag in the I band since 2005 April 9. The positional coincidence with the SWIFT and VLA detections and its photometric variability strongly suggest that this source is indeed the optical counterpart to IGR J17098-3628.
Follow-up photometric observations and the acquisition of a spectrum to characterise the optical counterpart are encouraged.
|
2005-05-16 08:27:00
|
radio,infra-red,optical,x-ray,black hole,neutron star,star,transient
|
495
|
4U 1715-390 and NGC 6440 in Outburst
|
C. B. Markwardt (NASA/GSFC and U. Maryland), J. H. Swank (NASA/GSFC)
|
RXTE Proportional Counter Array scans of the galactic bulge region have been continuing.
The burster in the globular cluster NGC 6440 (MXB 1746-20) appears to be entering outburst. The previous outburst was in October 2001. The 2-10 keV fluxes on May 12.6, 15.6 and 16.1 were 5.4 +/- 1.0, 7 +/- 3 and 21 +/- 1 mCrab, respectively. We appreciate inquiries by J. in 't Zand and R. Wijnands about this source.
The X-ray source 4U 1715-39 also may be starting an outburst. Scans on May 16.2 indicate a rise in flux of 4 mCrab (the baseline flux level is somewhat uncertain). Based on a Simbad reference search, little is known about this source aside from its detection, last reported in the HEAO A-1 catalog.
The source 4U 1850-087, in the globular cluster NGC 6712, reached a peak of 8 mCrab on April 3, 2005, after a gradual rise starting in May 2004. It is still at 4 mCrab.
|
2005-05-18 22:53:00
|
x-ray,globular cluster,neutron star,star,transient
|
496
|
Swift-UVOT Ultra-Violet/Optical Observations of GRO J1655-40
|
Albert K. H. Kong, Jeroen Homan, and Walter H. G. Lewin (MIT)
|
We report Swift-UVOT observations of GRO J1655-40 during the recent outburst. GRO J1655-40 has been observed with Swift for 9 times since April and the Ultra-Violet/Optical telescope (UVOT) obtained images through the U, B, V, UVW1, and UVW2 filters during 3 of the observations. GRO J1655-40 was clearly detected and we derived the following magnitudes:
2005 Apr 10: U=16.51+/-0.16, B=16.60+/-0.09, V=15.12+/-0.09, UVW1=18.12+/-0.24, UVW2=19.15+/-0.28 2005 May 14: U=17.38+/-0.18, B=17.47+/-0.11, V=15.86+/-0.10, UVW1=18.90+/-0.27, UVW2=20.18+/-0.33 2005 May 16: U=18.08+/-0.18, B=17.91+/-0.10, V=16.32+/-0.10, UVW1=19.52+/-0.28, UVW2=20.27+/-0.32
The bandpass of the UVW1 and UVW2 filters is centered at 251nm (width=70nm) and 188nm (width=76nm), respectively. We note that the B and V magnitudes are consistent with ground-based observations (ATEL #485).
Simultaneous X-ray observations taken with the XRT show an increasing trend in luminosity; the mean 0.3-10 keV count rate is 816 c/s (Apr 10), 1235 c/s (May 14), and 1697 c/s (May 16). In particular, the last two observations show significant variability, consistent with the RXTE observations (ATEL #487). The anti-correlation between UV/optical and X-ray fluxes is probably related to the state change that occurred on May 10 (ATEL #485, #486, and #487).
The Swift-UVOT magnitudes are based on a preliminary zero-point, measured in orbit, and will require refinement with further calibration.
|
2005-05-20 02:00:00
|
optical,ultra-violet,x-ray,binary,black hole,transient
|
497
|
INTEGRAL observation of the blazar 3C454.3 in outburst
|
L. Foschini, G. Di Cocco, G. Malaguti (INAF/IASF, Sezione di Bologna), E. Pian (INAF, Astronomical Observatory of Trieste), G. Tagliaferri, G. Ghisellini, L. Maraschi (INAF, Astronomical Observatory of Brera), P. Giommi (ASI-ASDC), N. Gehrels (NASA-GSFC), R. Walter, D. Eckert (ISDC) on behalf of a large collaboration
|
The blazar 3C 454.3 (z = 0.859) has been observed by INTEGRAL as a Target-of-Opportunity for 200 ks, starting on May 15, 2005, at 18:40 UT following the announcement of a bright state at various frequencies (see Balonek, VSNET Alert; Remillard, ATel 484; Trushkin et al., ATel 488).
The source was clearly detected by the IBIS/ISGRI instrument in the 20-40 and 40-100 keV energy bands, with a significance of 20 and 15 sigma, respectively. The flux averaged over the whole exposure in the 20-100 keV band is 1.6x10-10 erg cm-2 s-1.
No further INTEGRAL observations are planned.
|
2005-05-20 22:27:00
|
x-ray,gamma ray,agn,blazar,quasar,transient,request for observations
|
498
|
Discovery of XTE J1747-274
|
C. B. Markwardt (U. Maryland & NASA/GSFC), J. H. Swank (NASA/GSFC)
|
A new source has appeared in scans of the galactic center by the RXTE Proportional Counter Array (PCA). The flux increase first became noticeable in PCA scans on May 11, 15 and 18. Unfortunately, because this region of the sky is relatively crowded, the flux increase was attributed to the nearby source GCRT J1746-2757.
On May 20, 14h UT, the flux had become bright enough to be distinct from other nearby sources. We fitted for the position in the bulge scan data, and found R.A. = 17h47m38s, Decl. = -27o26m (J2000), and thus designate the source XTE J1747-274.
Because there are a number of bright sources nearby, the position error is dominated by systematic uncertainties. Based on two trial fits, we estimate the error to be < 8 arcmin. There are no catalogged galactic X-ray sources within 15 arcmin of this position.
After re-processing the PCA scan data of the past few months with the new source included, no flux increase in GCRT J1746-2757 is needed. The fluxes of XTE J1747-274 on May 11.4, 15.6, 18.3 and 20.6 were 12 +/- 3, 17 +/- 4, 10 +/- 2 and 48 +/- 4 mCrab (2-10 keV), respectively. Thus the source appears to be brightening irregularly.
No pulsations or QPOs are detectable in the brief (10-20 second) PCA scan passes over the source.
|
2005-05-24 00:25:00
|
x-ray,binary,black hole,neutron star,star,transient,request for observations
|
499
|
Discovery of SNF20050519-000, a Type Ia Supernova
|
The Nearby Supernova Factory: P. Antilogus, G. Garavini, S. Gilles, R. Pain (Laboratoire de Physique Nucleaire et de Haute Energies de Paris), G. Aldering, S. Bailey, B. C. Lee, S. Loken, P. Nugent, S. Perlmutter, R. Scalzo, R. C. Thomas, L. Wang, B. Weaver (Lawrence Berkeley National Laboratory, Berkeley, CA), C. Bonnaud, E. Pecontal (Centre de Recherche Astronomique de Lyon), N. Blanc, S. Bongard, Y. Copin, E. Gangler, L. Sauge, G. Smadja (Institut de Physique Nucleaire de Lyon), R. Kessler (Kavli Institute for Cosmological Physics, Chicago, IL), C. Baltay, D. Rabinowitz, A. Bauer (Yale)
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The Nearby Supernova Factory reports the discovery of SNF20050519-000 (coordinates RA 21:35:52.5 DEC -26:27:03.5 J2000.0) in an image obtained May 19.5 UT with the QUEST II camera on the Palomar Oschin 48-inch telescope as a part of the JPL Near-Earth Asteroid Tracking component of the Palomar Consortium. A spectrum (range 320-1000 nm) of this object, obtained May 24.6 with the Supernova Integral Field Spectrograph on the University of Hawaii 2.2-meter telescope, shows it to be a Type Ia SN approximately three weeks past maximum brightness. Its spectrum, dominated by iron-peak features blueward of 500 nm, closely resembles that of SN 1994D at the same phase. The redshift derived from this comparison is consistent with that of the host galaxy (2MASX J21355254-2627050, z=0.0304) as given by NED.
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2005-05-25 00:36:00
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asteroid,supernovae
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500
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Swift XRT Observation of the XTE J1747-274 field
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J. A. Kennea, D. N. Burrows (PSU), C. Markwardt (UMD/GSFC), N. Gehrels (GSFC)
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Starting on May 23rd 2005, 22:09UT the Swift observatary observed a field centered on the RXTE source RXTE J1747-274 (Markwardt et al., ATEL #498). After ground processing we obtained 1261s of Photon Counting mode data from the Swift XRT. From these data we find a bright point source located at: RA(J2000): 17:47:17.8 Dec(J200): -27:20:39
We estimate an uncertainty of 6 arcseconds radius (90% containment). We note that this source is 66 arcseconds away from the INTEGRAL detected transient IGR J17473-2721 (Grebenev et al., ATEL #467) and 7 arcminutes from the RXTE position. This is the only source detected in the XRT field of view and we conclude that the source detected in this field is in fact IGR J17473-2721.
The spectrum of this source is highly absorbed, and best fit with a power-law spectrum. The best fit parameters are N_H = (5.2 +/- 0.4) x 10^22 cm^-2 with a photon index of 2.12 +/- 0.16 (errors quoted at 90% confidence). The flux from this source in the 0.5-10 keV range is (8.4 +/- 0.9) x 10^-10 erg/s/cm^2. Assuming a distance of 8.5 kpc and correcting for absorption this gives an X-ray luminosity of approximately 2 x 10^37 erg/s (0.5 - 10 keV).
It is noted that this flux is approximately a factor of ten lower than the flux reported from XTE J1747-274 in ATEL #498. Continuing measurements of XTE J1747-274 with RXTE have shown that the source continues to be visible at the flux level seen on May 20th. Therefore we suggest that XTE J1747-274 is in fact outside of the XRT field of view, which is defined as as a box with the corners at the following coordinates: (1) RA=17:48:21 Dec=-27:21:08 (2) RA=17:46:58 Dec=-27:17:04 (3) RA=17:46:42 Dec=-27:34:49 (4) RA=17:48:06 Dec=-27:38:12
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2005-05-25 06:25:00
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x-ray,transient
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