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301
|
Another X-Ray Brightening of H 1743-322 = IGR J1746-3213
|
Jean Swank(NASA/GSFC)
|
The black hole candidate X-ray transient H 1743-322 = IGR J1746-3213 = XTE J17464-3213, which went into outburst in March 2003 (ATEL#132,#133) and decayed below the RXTE PCA sensitivity limit sometime between Nov 2 and 2004 Feb 7, while it was too close to the sun, has brightened again. On Jul 3, the PCA scans of the galactic bulge detected it at a 2-10 keV intensity of 16(1) mCrab and on Jul 7, it had risen to 69(2) mCrab. The RXTE ASM had no observations of it Jun 29 - Jul 6 but saw 60(70)-160(30) mCrab Jul 6-10. Additional RXTE observations are planned on Jul 11. It has previously been an active radio transient (first reported in ATEL#137).
|
2004-07-11 03:17:00
|
radio,x-ray,binary,black hole,the sun,transient,request for observations
|
302
|
Radio observations of V4641 Sgr at 6 and 3 cm
|
Cliff Senkbeil (Univ of Tasmania), Bob Sault (Australia Telescope National Facility)
|
Australia Telescope Compact Array observations of V4641 Sgr on 7 July show a clear detection at 6 and 3 cm (4.80 and 8.64 GHz). For observations taken between 14.5 to 19.0 hours UT, the flux density was seen to vary between approximately 5mJy and 30mJy. In particular, a sudden increase was noted at 16.4 UT, followed by a decay over several hours. The 3cm flux density peaked approximately 20 minutes earlier than the 6cm signal.
The light curve of the observation can be found at
http://www.atnf.csiro.au/people/rsault/astro/v4641/
|
2004-07-11 09:04:00
|
radio,binary,black hole,transient,request for observations
|
303
|
V4641 Sgr: continued radio flaring
|
M. P. Rupen, V. Dhawan, A. J. Mioduszewski (NRAO)
|
We report further Very Large Array (VLA) observations of the black hole candidate binary V4641 Sgr, currently active at optical, X-ray, and radio wavelengths (see ATEL #295, ATEL #296, ATEL #297, ATEL #299, ATEL #300, ATEL #302):
These data in conjunction with earlier observations from the VLA (ATEL #296), RATAN (ATEL #300), and the ATCA (ATEL #302) indicate that V4641 Sgr continues to be quite active at radio wavelengths, undergoing a series of fairly large flares. Simultaneous X-ray and optical observations would be very valuable (see http://www .aoc.nrao.edu/~mrupen/XRT/V4641Sgr/v4641sgr.shtml).
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
|
2004-07-12 06:51:00
|
radio,optical,x-ray,binary,black hole,transient,variables
|
304
|
Radio observations of H1743-322 = IGR J1746-3213 = XTE J17464-3213
|
M. P. Rupen, V. Dhawan, A. J. Mioduszewski (NRAO)
|
We report Very Large Array (VLA) observations of the black hole candidate binary H1743-322 = IGR J1746-3213 = XTE J17464-3213, currently undergoing an X-ray outburst (ATEL #301). Data taken on 11 July 2004 show no detections at 4.86 and 8.46 GHz, with nominal flux densities at the position of the source of 0.17 +/- 0.23 mJy/beam and 0.10 +/- 0.08 mJy/beam respectively. Observations on 27 June 2004 also showed no source, the nominal flux density being 0.07 +/- 0.07 mJy/beam at 8.46 GHz. Regular monitoring observations at one to two week intervals gave a possible (3sigma) detection of the core on 9 April 2004 (0.15 +/- 0.05 mJy/beam at 4.86 GHz). The last clearly believable detection was however towards the end of the X-ray hard state (ATEL #198), on 6 November 2003, when the flux density was 0.22 +/- 0.04 mJy at 4.86 GHz. Further radio observations are planned at few-day to weekly intervals.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
|
2004-07-12 06:55:00
|
radio,x-ray,binary,black hole,star,transient,variables
|
305
|
New Outburst of the Ultraluminous Supersoft X-ray Source in M101
|
A. K.H. Kong (Harvard-Smithsonian Center for Astrophysics)
|
A new outburst of the ultraluminous supersoft X-ray source in M101 (CXOU J140332.3+542103) was detected during a recent 9.9 ks Chandra observation on 2004 July 5. More than 200 counts was detected and the energy spectrum can be fit with an absorbed blackbody model with kT=70+/-15 eV and N_H=(2.2+/-1.7)e21 cm^-2 (90% uncertainties). The unabsorbed 0.3-7 keV luminosity is 7.4e39 erg/s (d=6.7 Mpc) and the bolometric luminosity is 2e40 erg/s (derived from the normalization). The source entered the low/hard state in 2004 January with 0.3-7 keV luminosity of ~3e37 erg/s (ATEL #222); it was marginally detected with 10 counts (0.1-7 keV) in the last Chandra observation (42 ks) taken on 2004 May 9. The recent Chandra observations indicate that the source is currently in transition, possibly from the low/hard state to the high/supersoft state.
|
2004-07-13 13:19:00
|
x-ray,binary,black hole,transient
|
306
|
Outburst of the Ultraluminous Supersoft X-ray Source in M101
|
A. K.H. Kong (Harvard-Smithsonian Center for Astrophysics)
|
We report further Chandra observations of the ultraluminous supersoft X-ray source in M101, currently in outburst (ATEL #305). Data taken on 2004 July 6 (for 28 ks) and 2004 July 8 (for 54 ks) show that the source is in high/supersoft state. Preliminary analysis shows that the energy spectrum of the first observation can be fit with an absorbed blackbody model (N_H=2.8e21 cm^-2, kT=105 eV) plus two absorption edges at 0.66 keV and 0.87 keV. The 0.3-7 keV luminosity is 1e40 erg/s and the bolometric luminosity is 1.7e40 erg/s (d=6.7 Mpc). During the second observation on July 8, the energy spectrum can be fit with an absorbed blackbody model (N_H=1.4e21 cm^-2, kT=56 eV) plus two absorption edges at 0.33 keV and 0.56 keV. The 0.3-7 keV luminosity is 8e39 erg/s and the bolometric luminosity is 8e40 erg/s. During both observations, the source exhibits significant timing variability. The spectra of the two observations can be obtained at http://hea-www.harvard.edu/~akong/SSSjuly6.ps and http://hea-www.harvard.edu/~akong/SSSjuly8.ps.
|
2004-07-14 16:11:00
|
x-ray,binary,black hole,transient
|
307
|
Her X-1 Exiting Anomalous Low State
|
Patricia Boyd (NASA/GSFC and UMBC) Martin Still (NASA/GSFC and USRA) and Robin Corbet (NASA/GSFC and USRA)
|
Recent RXTE All-Sky Monitor (ASM) measurements of the X-ray flux of Her X-1 (= HZ Her) suggest that the source has exited the anomalous low state (ALS) and is again exhibiting long-term variability with a period near 35 days. Current (MJD 53196.8) RXTE ASM average count rates are above 5 counts/s, whereas during ALS the ASM rate is typically below 2 counts/s at every long term phase. (One Crab=75 counts/s in the ASM). Preliminary analysis of a pointed RXTE Proportional Counter Array (PCA) observation obtained 2004-July 12 finds the source to be significantly brighter than during an ALS, with a count rate of ~ 0.1 Crab (> 5 ASM counts/s) and large amplitude pulsations. In addition, another weaker but marginally significant ASM maximum was seen 35 days previously at peak time ~MJD 53163. This would be the fourth time Her X-1 has been observed to return to large-amplitude long-term variability after an anomalous low state. (During an ALS, the 35 day X-ray cycle turns off yet the 35-day optical cycle continues unabated.) The 1.24-s pulse period of Her X-1, typically spinning up, has been observed to spin down correlated with the behavior of ALS. Analysis of the PCA data continues. Pointed observations over energy bands from IR to hard X-rays, to investigate the coupling of the spin and (presumably) accretion disk precession periods, are encouraged as the source evolves.
|
2004-07-15 05:13:00
|
optical,x-ray,binary,neutron star,pulsar,star,request for observations
|
308
|
Optical observations of the field around the X-ray pulsars XTE J1858+034 and GRO J2058+42
|
Pablo Reig (University of Crete), Tasos Kougentakis (University of Crete), Giannis Papamastorakis (University of Crete)
|
We report photometric and spectroscopic optical observations of the likely optical counterparts to the 221-s XTE J1858+034 (Remillard & Levine and Takeshima & Corbet, 1998, IAUCirc 6826) and the 196-s high-mass X-ray binary (HMXB) pulsars GRO J2058+42 (Wilson et al. 1996, IAUCirc 6514, Wilson et al. 1998, ApJ, 499, 820).
Optical photometric observations of the field around the best-fit ISGRI/IBIS INTEGRAL position R.A.=18h58m43s, Decl.=03d26m06s (Molkov et al, 2004, ATel 274) of XTE J1858+034 using Johnson BVR and a H alpha filter were carried out on the night 20 May 2004 (JD 2,453,146.45) with the 1.3-m telescope of the Skinakas Observatory (Crete, Greece). Based on the strength of the Halpha line several candidates were identified. Subsequent spectroscopic observations revealed that only one exhibits Halpha emission. The position of the proposed candidate (from Aladin Sky Atlas) is R.A.= 18h58m36s, Decl.=03d26m09s consistent with the ISGRI/IBIS uncertainty, although outside the JEMX error circle as given by Molkov et al. Measured photometric magnitudes are B=19.63 V=18.01 R=16.94 with an uncertainty of 0.03 mag. The mean equivalent width of the H alpha line is -6.5 Angstroms.
We also performed optical photometric and spectroscopic observations of the best-fit GRO position of the X-ray source GRO J2058+42. These observations points to the star located at R.A.= 20h58m47s, Decl.=41d46m36s as the likely optical counterpart of this X-ray pulsar. The photometric data were obtained on three nights: 7 June 2003 (JD 2,452,798.494), 8 June 2003 (JD 2,452,799.442) and August 24, 2003 (JD 2,452,876.380) and resulted in the following mean magnitudes B=16.04, V=14.92, R=14.23 and I=13.49, with an error of 0.03 mag. Spectra obtained on 25 June 2004 (JD 2,453,182.444) and 6 July 2004 (JD 2,453,193.491) of the proposed candidate show a double-peak Halpha profile with a mean equivalent width of -4.5 Angstroms.
Emission lines together with IR excess and V/R variability (changes in the relative strength of the blue and red peaks of a double peaked line) are the signatures of Be stars. The origin of these two observational properties resides in the presence of a circumstellar disk formed with matter expelled from the photosphere of the Be star in a way that it is still not fully understood. The double-peak profile of the H alpha line seen in the low resolution spectra of GRO J2058+43 and its transient nature give support to its classification as a Be/X-ray binary. Supergiant X-ray binaries (the other type of HMXB) may also show H alpha in emission. The equivalent width and shape (a single and narrow peak) of the H alpha line in XTE J1858+034 are not incompatible with the system containing an evolved companion. Further higher resolution spectra are needed to find out its spectral type.
|
2004-07-15 21:26:00
|
optical,x-ray,binary,pulsar,star,transient
|
309
|
V4641 Sgr: new optical flaring
|
I. Bikmaev (KSU), I. Khamitov, Z. Aslan (TUG), N. Sakhibullin (KSU), R. Burenin, M Pavlinsky (IKI), M. Revnivtsev, R. Sunyaev (IKI, MPA)
|
We have performed photometric time-series observations (Rc-band) of X-ray binary system V4641Sgr with the Russian-Turkish telescope RTT150 at the TUBITAK National Observatory (Turkey) during the period of 18:33-23:32 UT, July 17,2004. Several optical flaring with increasing of brightness amplitude up to 0.6 mag have been detected. Obtained Light curve with the time resolution of 16.8 sec can be seen in http://db.rsdc.rssi.ru/V4641Sgr/2004/lc040717.jpg Orbital variations of V4641 Sgr in quiescence (Goranskij et al., Astron.Rep., 2003, v.80, N9) with data points obtained on July 17, 2004 can be seen in http://db.rsdc.rssi.ru/V4641Sgr/2004/ph040717.jpg Given strong optical variability the source obviously in some active state. Simultaneous X-ray and optical observations are crucial for investigations of the nature of the observed activity.
|
2004-07-18 21:14:00
|
optical,x-ray,binary,black hole,request for observations
|
310
|
IGR J18027-1455 / USNO-B1.0 0750-0506536 is an AGN
|
N. Masetti, E. Palazzi, L. Bassani, A. Malizia, J. B. Stephen (IASF/CNR-INAF Bologna Italy)
|
It has recently been suggested that the radio/near-infrared/optical and soft X-ray sources NVSS J180247-145451, 2MASXi J1802473-145454, USNO-B1.0 0750-0506536 and 1RXS J180245.5-145432 are in fact the same object and this is also considered as the most likely counterpart of the new INTEGRAL/IBIS source IGR J18027-1455 (ATel #229, #246). In order to identify the high energy object and to establish its relation to the other sources, a 20-minute spectrum of USNO-B1.0 0750-0506536 was acquired on July 15, 2004 with BFOSC at the `G.D. Cassini' 1.5m telescope located in Loiano (Italy) under a seeing of 1.5 arcsec. The resulting spectrum, covering the 4000-8500 Angstroms range, is dominated by a strong redshifted line complex corresponding to Halpha and [NII] and shows other emission lines typical of an AGN, likely a type 1 Seyfert. The redshift is estimated to be z=0.036, corresponding to a source distance of 144 Mpc (Ho=75 Km/sec/Mpc). At this distance, the source X-ray luminosity is 2.3 x 10^42 erg/sec and 1 x 10^44 erg/sec in the 0.1-2.4 keV and 20-40 keV band respectively, locating IGR J18027-1255 among the brightest Seyferts detected so far. The absolute B magnitude of the object is about -22. The extragalactic nature is compatible with the extension seen both in the IR and optical wavebands and is likely due to the galaxy surrounding the AGN.
|
2004-07-20 20:30:00
|
radio,infra-red,optical,x-ray,gamma ray,agn,black hole
|
311
|
Radio observations of the ultraluminous supersoft X-ray source in M101
|
M. P. Rupen (NRAO), L. O. Sjouwerman (NRAO), A. K.H. Kong (Harvard-Smithsonian Center for Astrophysics)
|
We report Very Large Array (VLA) observations of the ultraluminous supersoft X-ray source in M101, currently undergoing a strong X-ray outburst (ATEL #305, ATEL #306). Data taken on 21 July 2004 show no detections at 4.86 and 8.46 GHz, with nominal flux densities at the Chandra position (ATEL #305) of 0.093 +/- 0.033 mJy/beam and 0.007 +/- 0.025 mJy/beam respectively. The 4.86 GHz data at this position are partially contaminated by a nearby (14 arcseconds away) confusing source, CasHII. Removing that source, under the assumption that it is point-like, gives a nominal flux density for the ULX of 0.007 mJy/beam.
The raw and calibrated uv-data, together with deconvolved FITS images and contour plots, are available at http://www.aoc.nrao.edu/~mrupen/XRT/M101ULX/m101ulx.shtml.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
|
2004-07-22 01:05:00
|
radio,x-ray,binary,black hole,transient,variables
|
312
|
Radio observations of BD +60 73 = IGR J00370+6122
|
P. B. Cameron (1, 2), J. Grcevich (1, 3), N. Gugliucci (1, 4), K. Hess (1, 5), C. Ly (1, 6), K. Schillemat (1, 7), A. Shetiya (1, 8), C. Simpson (1, 9), A. Stilp (1, 3), Urvashi Rao Venkata (1, 10), B. Zeiger (1, 11) (1 NRAO; 2 Caltech; 3 U. of Wisconsin-Madison; 4 Lycoming College; 5 Cornell U; 6 U of Arizona; 7 Clarkson U; 8 New Mexico Tech; 9 Wellesley College; 10 UCSD; 11 Willamette U)
|
We report Very Large Array (VLA) D-configuration observations of recently discovered High Mass X-ray Binary IGR J00370+6122 = BD +60 73 (ATEL #281, #282, #285). Data taken by the VLA Summer Students on 9 July 2004, from 16:58 to 18:58 UT, show no detections at the frequencies listed below with the nominal flux densities measured at the position of BD +60 73.
Error bars are 1 sigma. At 1.46 and 4.86 GHz the field-of-view is large enough to cover the full INTEGRAL error circle (ATEL #281), and we see no sources in that region to the noise levels indicated. The raw data are publicly available via the NRAO Data Archive.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
|
2004-07-24 07:06:00
|
radio,x-ray,gamma ray,binary,neutron star,star,variables
|
313
|
Gradual Brightening of SGR 1806-20
|
Peter M. Woods (USRA/NSSTC), Chryssa Kouveliotou (MSFC/NSSTC), Ersin Gogus (Sabanci Univ), Sandy Patel (USRA/NSSTC), Kevin Hurley (UCB), and Jean Swank (NASA/GSFC)
|
The Soft Gamma Repeater SGR 1806-20 became particularly burst active in May 2004 (GCN 2603, 2604) and has remained active up through the present. Over this interval, both the pulsed X-ray flux as measured with the RXTE/PCA and the phase-averaged X-ray flux as measured with Chandra/ACIS have been 2 to 3 times higher than ever observed since the discovery of the X-ray counterpart in 1993. In the Chandra X-ray data, we detect a thermal component in the X-ray spectrum of SGR 1806-20 for the first time. We measure a blackbody temperature of 0.54 +/- 0.07 and a photon index of -1.44 +/- 0.15. Surprisingly, the pulsed flux as measured during several RXTE pointings over the last two months has actually risen by 40-50% as the burst rate declined during the same time interval. Given the unprecedented, continued brightening of the source, additional observations, particularly in soft and hard X-rays and IR, are encouraged.
|
2004-07-29 01:45:00
|
infra-red,x-ray,gamma ray,soft gamma-ray repeater,request for observations
|
314
|
Renewed radio activity in H1743-322 = IGR J1746-3213 = XTE J17464-3213
|
M. P. Rupen, A. J. Mioduszewski, V. Dhawan (NRAO)
|
Very Large Array (VLA) observations of the black hole candidate binary H1743-322 = IGR J1746-3213 = XTE J17464-3213 (e.g., ATEL #301, ATEL #304) show renewed radio activity on 5 August 2004. Two sets of scans, from 01:18 to 01:34 and 03:34 to 03:46 UT, were consistent with a steady flux density of 1.96 +/- 0.15 mJy at 4.86 GHz. Observations on 4 August 2004 from 05:21 to 05:29 UT gave no detection, with a nominal value at the source position of 0.14 +/- 0.17 mJy/beam at the same frequency. Based on past experience with this and other sources, the radio rise probably corresponds to a state change in the accretion disk, most directly reflected in a hardening of the on-going X-ray flare.
During last year's outburst (e.g., ATEL #142) the source remained optically thick in the radio for almost two weeks, then began a series of chaotic radio flares. That slow, inverted-spectrum rise is very unusual among X-ray binaries; assuming the source is currently beginning a similar outburst, multi-wavelength observations would be extremely useful in understanding this phase.
The best radio position for the core is:
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
|
2004-08-07 01:14:00
|
radio,infra-red,optical,x-ray,binary,black hole,transient
|
315
|
V4641 Sgr returns to quiescence; deep observations planned
|
M. P. Rupen (NRAO), P. G. Jonker (CfA), A. J. Mioduszewski, V. Dhawan (NRAO), R. P. Fender (U. Amsterdam), & G. Dubus (LLR)
|
Observations of the X-ray binary V4641 Sgr (e.g., ATEL #309, ATEL #303) with the Very Large Array (VLA) show that the object has returned to quiescence. Our last clear detection was on 20 July 2004, when the 4.86 GHz flux density remained steady at 2.0 +/- 0.2 mJy in two five-minute observations centered on 05:06 and 08:53 UT. Data taken at the same frequency on 23 July 2004 gave a nominal flux density at the position of the source of 0.27 +/- 0.09 mJy/beam, while 8.46 GHz observations on 23, 27, 28, 31 July, 1 August gave nominal flux densities of 0.09 +/- 0.05, 0.06 +/- 0.08, 0.05 +/- 0.04, 0.105 +/- 0.034, and 0.00 +/- 0.10 mJy/beam, respectively.
A 20ksec observation with Chandra on July 30 detected 15 source counts (i.e., 8.75e-4 c/s). Although this is somewhat higher than the quiescent source count rate of 3e-4 c/s seen by Tomsick et al. (2003), this indicates that the source is also approaching X-ray quiescence.
These X-ray and radio observations are consistent with optical reports on VSNet (cf. http://www2.yukawa.kyoto-u.ac.jp/~uemura/v4641sgr/index.html ) which indicate strong activity on July 19/20, followed by a return to ordinary ellipsoidal variations by the 23rd. Note however that in previous years flares were observed for several months after the initial outburst.
In addition to on-going VLA monitoring, a simultaneous Chandra (40 ksec) + VLA (8 hour) observation is scheduled from 23:55 UT on 9 August 2004, to 07:54 UT on 10 August 2004. Simultaneous optical and near infrared observations are strongly encouraged.
|
2004-08-07 01:58:00
|
radio,infra-red,optical,x-ray,binary,black hole,transient,variables,request for observations
|
316
|
GX 339-4 : Significant decline in IR and Optical
|
M. M. Buxton, C. D. Bailyn (Yale)
|
We have been making daily optical and infrared observations of the black-hole candidate and microquasar GX 339-4 using ANDICAM on the SMARTS 1.3m telescope at CTIO. Data obtained on UT Aug 05, 06 and 08 show that GX 339-4 has become significantly fainter since UT Jul 31, and that the magnitude of this change increases with wavelength. The difference in magnitude between UT Jul 31 and UT Aug 08 are as follows: dV=0.14, dI=0.26, dJ=0.50, dH=0.68. The magnitudes as of UT Aug 08 are as follows: V=16.2, I=14.4, J=14.0, H=13.4. Sharp rises dominated by the IR have been observed in several sources, and have been interpreted as the onset of synchrotron emission associated with a jet (e.g. Buxton & Bailyn 2004 ApJ, accepted, astro-ph/0408156 and references therein). By analogy, this oppositely directed event might mark an abrupt end to jet activity, suggesting that GX 339-4 may have up until now been in an active 'jet state' but with different characteristics in the light curve to that seen in 2002/2003. Our most recent V- and J-band light curves can be seen at http://www.astro.yale.edu/buxton/smarts/light_curves/gx339.html.
|
2004-08-10 03:14:00
|
optical,binary,black hole,transient
|
317
|
XTE J1829-098: a New 7.8 s Period Pulsar
|
C. B. Markwardt (U. Maryland & NASA/GSFC); J. H. Swank (NASA/GSFC); E. A. Smith (NASA/GSFC)
|
Within the past three months, RXTE PCA monitoring observations of the galactic center region have been enlarged to include portions of the galactic plane on either side of the galactic bulge. The scans extend to about +/- 25 degrees in galactic longitude and +/- 4 degrees in galactic latitude.
Scans on July 30.9 (UTC) detected a new source with intensity ~7 mCrab. In follow-up pointed PCA observations on August 5.3, the source was detected as an X-ray pulsar. The pulse period is 7.82 +/- 0.05 s. Preceding the July 30.9 observation, there were five PCA scans between May 22 and June 10, where the source was not detected, with upper limit ~2 mCrab.
A dedicated PCA scan for position was performed on August 8.5. The scans were fit to a model which included components from the galactic ridge (~2 mCrab) and the nearby supernova remnant G21.5-0.9 (~5 mCrab). The best fit pulsar position is R.A. = 18h29m35s, Decl. = -09d51' (J2000). The 99% confidence region is approximately elliptical with semimajor axes of 3.8' (R.A.) and 3' (Decl.). We designate this source XTE J1829-098.
After accounting for the galactic ridge emission, which contaminates the field of view, the spectrum of XTE J1829-098 is consistent with an absorbed power law with high energy cut-off. The N_H value was 10^{23} cm^{-1}, the power law photon index 1.0, and the cut-off energy was 9.8 keV. The 2-10 keV flux was 1.0 x 10^{-10} erg cm^{-2} s^{-1}.
Although the pulse period is close to those of Anomalous X-Ray Pulsars, the spectrum is as hard as spectra of high mass binaries. 4U 1626-67 also has a similar period and a hard spectrum. The closest cataloged X-ray source appears to be 1WGA J1830.1-0954, which is nominally 9' away, and thus outside of our quoted 99% error contour. In 1994 the ROSAT flux of that source was 1.650 x 10^{-13} ergs s^{-1} cm^{-2}. SIMBAD reports no bright stars within the error contour, but there are many with V>16 mag.
|
2004-08-10 10:02:00
|
x-ray,binary,neutron star,pulsar,star,supernova remnant,supernovae,transient
|
318
|
GX 339-4 leaving the hard X-ray state - radio flare expected
|
Jeroen Homan (MIT)
|
Recent Rossi X-ray Timing Explorer observations of the black hole transient GX 339-4 show that the source is leaving the bright hard state. The evolution of the spectral and variability properties is very similar to the behavior seen during the outburst of GX 339-4 in 2002: the spectral power-law component has started to steepen and QPO frequencies are increasing. Observations in the optical/IR (see ATEL #316) further strengthen the similarities. If the analogy with the 2002 outburst holds and the time scale for the transition is the same, we expect the source to enter the very high state around August 14. In 2002 a large radio flare that lasted for a few hours was observed 1-2 days before the transition to the very high state, which would correspond to August 12-13 for the current transition. Radio, optical/IR and X-ray observations of the source for the next few days are therefore strongly encouraged. We note that the current transition is occurring at a luminosity that is lower by a factor of ~4 than in 2002, showing that these changes are probably not determined by the instantaneous mass accretion rate. Radio, optical/IR and X-ray coverage of such a transition at a different mass accretion rate could help to uncover the role of this parameter in the states of black hole X-ray binaries.
|
2004-08-11 05:57:00
|
radio,infra-red,optical,x-ray,binary,black hole,transient,request for observations
|
319
|
XMM-Newton Detection of the 7.8 s Pulsar XTE J1829-098
|
J. P. Halpern, E. V. Gotthelf (Columbia U.)
|
An outburst of the newly discovered 7.8 s pulsar XTE J1829-098 (Markwardt et al., ATEL #317) is seen in an unpublished XMM-Newton Galactic Plane Survey observation taken on 2003 March 27, when the source had a barycentric pulse period of 7.840+/-0.002 s and a count rate of 4.5 counts/s in the EPIC pn camera. Its position is R.A. = 18h29m44.0s, Decl. = -09d51'23" (J2000). The standard 90% confidence position uncertainty is 4". The spectrum is fitted, but not very well (chisquare = 48.5 for 33 d.o.f.), by a power law of photon index 0.9+/-0.2 and N_H = (6+/-1)x10^{22} cm^{-2}. The 2-10 keV flux is 5.6x10^{-11} ergs cm^{-2} s^{-1}. In comparison with the total Galactic 21 cm column in this direction of 1.8x10^{22} cm^{-2}, this suggests that most of the absorption is intrinsic to the source. In additional XMM pointings at the same field, the source was not detected on 2002 March 27 and 2003 September 13. See Hands, Warwick, Watson, & Helfand, MNRAS, 351, 31-56 (2004) for details of the XMM-Newton Galactic Plane Survey.
|
2004-08-11 10:36:00
|
x-ray,pulsar
|
320
|
Phototyping of SN2004cs with the Palomar 60-inch telescope
|
A. Rajala, D. B. Fox, and A. Gal-Yam (Caltech)
|
We have observed SN2004cs (IAUC 8361 ) in the Johnson BVR and Gunn g bands with the robotic Palomar 60-inch (1.5-m) telescope + CCD imager. Data were obtained on June 24 UT, one night after the discovery report for SN2004cs, and calibrated with images obtained on July 30 UT. The derived magnitudes and uncertainties for SN2004cs on June 24.3 UT are: B=18.16(0.07) mag, V=18.06(0.07) mag, R=17.87(0.08) mag and g=18.23(0.05) mag. This combination of B-g and R-V colors is strongly suggestive of a type Ia identification for this event (see Gal-Yam et al. 2004, PASP, 116, 597; http://wise-obs.tau.ac.il/~dovip/typing, and references therein). For more details, please see the P60 Phototyping Webpage.
|
2004-08-12 21:52:00
|
optical,supernovae
|
321
|
Spectroscopic identification of SNe 2004ds and SN 2004dt
|
Avishay Gal-Yam (Caltech)
|
A. Gal-Yam, D. Fox and S. Kulkarni, California Institute of Technology, report on red spectra (range 550-780 nm) obtained by Kulkarni and Fox on Aug. 13.5 UT at the 10-m Keck I telescope (+ LRIS). The spectrum of of SN 2004ds (IAUC # 8386 ), shows a broad, well-developed P-Cyg H_alpha line and suggests that this is a type II supernova. The spectrum of SN 2004dt (IAUC # 8386 ), shows the distinctive Si II 6100 absorption trough around 6100 Angstrom, indicating this is a young SN Ia.
|
2004-08-14 07:47:00
|
optical,supernovae
|
322
|
Confirmation of the Transition to the Very High State in GX 339-4
|
D. M. Smith, S. K. Bushart (University of California, Santa Cruz)
|
Homan (2004, ATEL #318) recently predicted that black-hole candidate GX 339-4 would make a transition to the Very High State around August 14, and we find, also using data from the Rossi X-ray Timing Explorer, that this transition has occurred.
The photon spectral index had averaged around 1.50 for the past month in the hard state; the recent evolution has been: 1.54 at 6h on 5 August, 1.58 at 10h on 8 August, 1.81 at 0h on 12 August, 2.39 at 23h on 13 August, and 2.83 at 14h on 17 August. These values are taken from fits that included both the power law component and a disk blackbody component. It is notable that the J band luminosity of the system had already dropped by the better part of a magnitude on 8 August (Buxton and Bailyn, 2004, ATEL #316) at a time when the spectral softening in the x-rays had barely begun.
Despite the very soft spectral index, the power law still energetically dominates the thermal component as of 17 August. Furthermore, the power spectrum resembles that of the canonical hard state, not the soft state, being flat-topped at low frequencies and showing a prominent quasi-periodic oscillation at about 4 Hz. The total rms variability is still high, at 23%. This is therefore a Very High or Intermediate state, the difference between the two being somewhat unclear, particularly considering the relatively low luminosity at which this transition has occurred (Homan, 2004, ATEL #318).
The first plot linked below shows the RXTE PCA count spectra which give the power-law indices above, with the colors white, red, green, dark blue, and light blue corresponding to the chronological order above. The second plot shows the history of the current outburst, giving the count rate (in counts per second per RXTE PCU) and a simple measure of spectral softness (counts between 2.5 and 6.0 keV)/(counts between 8.0 and 25.0 keV). Day 0 on this plot is 13 February 2004. The preliminary, purely hard outburst may be part of the same event as the current activity, or it may be more or less independent. Data from the Burst and Transient Source Experiment on the Compton Gamma-Ray Observatory (Harmon et al. 2002, ApJS 138, 149) and from the RXTE All Sky Monitor (Levine et al. 1996, ApJ 469, L33) show that there was a long period of variable hard-state activity before the decisive soft-state outburst of 1998 (Zdziarski et al. 2004, MNRAS 351, 791).
Observations of this rare state at all wavelengths are encouraged.
|
2004-08-20 09:09:00
|
x-ray,gamma ray,binary,black hole,transient,variables,request for observations
|
323
|
GX 339-4: Continued Optical and Infra-red Decline
|
Charles Bailyn, Lisa Ferrara (Yale)
|
Ongoing observations of GX 339-4 by the SMARTS consortium 1.3m telescope and ANDICAM instrument at CTIO show a continuing sharp decline in optical and near-IR flux levels throughout the X-ray state transition described by Smith et al. (ATEL #322). Data taken starting August 20 UT=2:36 shows V=16.8, I=15.1, J=14.9, H=14.6. This constitutes a decline of 0.8, 1.0, 1.4 and 1.9 magnitudes respectively in V, I, J and H since July 31.
|
2004-08-21 02:49:00
|
infra-red,optical,x-ray,binary,black hole,transient
|
324
|
Burst Activity of SGR 1806-20 in the hard X-rays
|
S. Molkov (IKI, Moscow), P. Ubertini (IASF, Roma), C. Jorgensen (DSRI, Copenhagen), C. Winkler (ESA/ESTEC Noordwijk), N. Gehrels (GSFC, NASA)
|
During one of the regular Galactic Plan Scan performed by the High energy INTEGRAL satellite on 20-21 August, 2004 the Soft Gamma Ray Repeater SGR 1806-20 was in the field of view of the IBIS telescope during ~10 ks. Seven bursts were detected by the ISGRI/IBIS low energy detection plane from the source during this period in the energy band 18-70 keV. This frequency of bursts generation confirms that the source now stays in the active phase (ATEL #313).
The duration of the bursts varied from 30 ms to 240 ms (see the table below). The bursts profile have a complex structure. Two bursts were detected also by the JEM-X telescope in the energy band 3-20 keV. But the JEM-X fluxes are very weak and an accurate flux determination is pending.
================================================================ N | T_start | Dur. | Sign. | Mean FLUX, 18-70 keV | JEM-X (UT) (ms) (10^{-7} erg/s/cm2) 1 21T02:30:46.0 50 5.8 2.3 no 2 21T02:37:53.0 50 6.7 3.5 no 3 21T02:37:53.2 240 27.9 8.4 no 4 21T02:47:46.6 30 3.6 2.0 no 5 21T03:15:40.2 100 11.2 2.0 yes 6 21T03:38:26.7 190 27.6 7.4 yes 7 21T04:49:32.3 110 13.2 8.2 no
|
2004-08-26 00:12:00
|
x-ray,gamma ray,binary,soft gamma-ray repeater,request for observations
|
325
|
SGR 1806-20
|
S. Molkov (IKI, Moscow), K. Hurley (USB), A. Lutovinov (IKI, Moscow), R. Sunyaev (IKI, Moscow and MPA, Garching)
|
The Soft Gamma-Ray Repeater SGR 1806-20 was observed with INTEGRAL during the campaign of the Galactic Center monitoring on 21-24 Aug, 2004. These observations were preceded by the INTEGRAL Galactic Plan Scan in which the source exhibited bursting activity (ATEL#324).
The source was in the field of view of the IBIS telescope FOR ~120 ks and more than sixty bursts were detected IN the ISGRI/IBIS low energy detection plane (18-70 keV). A few of them were unusually long (>1s) and some were extremely powerful (mean flux up to 4 10^{-6} erg/s/cm2 in the 18-70 keV energy band). In addition, the mean persistent flux of SGR 1806-20 was AT A level of ~5 mCrab in the energy range 18-60 keV, which is approximately a factor of 2 higher than it was during autumn 2003 INTEGRAL observations.
The next observations of the region of SGR 1806-20 with INTEGRAL are scheduled for the period 18:30 Sept. 1, 2004 to 02:10 Sept. 2, 2004 (UT). Simultaneous observations, especially in soft X-rays, are encouraged.
|
2004-08-31 02:28:00
|
x-ray,gamma ray,soft gamma-ray repeater
|
326
|
New outburst from 4U0115+634
|
A. Lutovinov (IKI, Moscow), C. Budtz-Jorgensen (DSRI, Copenhagen), M. Turler (ISDC, Versoix), P. Kretschmar (ISDC, Versoix, MPE, Garching), W. Hermsen (SRON, Utrecht), E. Kuulkers (ESTEC, Noordwijk)
|
During the last galactic plane scans performed with the INTEGRAL observatory on 29 Aug, 2004 an increase of the flux from 4U0115+634 was detected, that can be connected with the beginning of possible new outburst. The source was detected with IBIS and JEM-X telescopes around UT17:00 with a total effective exposure of a few ksec at the level of ~10 mCrab and 25-30 mCrab in 18-60 keV and 4-20 keV energy ranges, respectively. We encourage follow up observations at various wavelengths.
|
2004-09-01 22:05:00
|
x-ray,neutron star,pulsar,star,request for observations
|
327
|
Long duration X-ray burst from GX 3+1
|
S. Brandt, N. Lund, J. Chenevez, C. Budtz-Jorgensen (DSRI, Copenhagen), P. Goldoni, G. Belanger, A. Goldwurm (CEA, Saclay), E. Kuulkers (ESA, ESTEC)
|
During an observation of the Galactic Center the JEM-X instrument on INTEGRAL detected an unusally long X-ray burst from GX 3+1. The burst began on August 31 at 18:57 UTC
After an precursor spike lasting 7 s where the burst reached a flux of about 2000 mCrab in the 4 to 20 keV band the flux fell to around 500 mCrab and then decayed with an e-folding time of about 700 s. This burst appear as intermediate between the normal type-I X-ray bursts (e-folding times up to a few tens of seconds) and the very long "superbursts" (e-folding times of several hours).
Prior to the outburst the source flux was about 150 mCrab.
Follow-up observations are encouraged.
|
2004-09-02 17:11:00
|
x-ray,neutron star,star,request for observations
|
328
|
IGRJ17331-2406
|
A. Lutovinov (IKI, Moscow), M. Cadolle Bel (CEA, Saclay), G. Belanger (CEA, Saclay), A. Goldwurm (CEA, Saclay), C. Budtz-Jorgensen (DSRI, Copenhagen), N. Mowlavi (ISDC, Versoix), J. Paul (CEA, Saclay), A. Orr (ISOC/ESTEC, Noordwijk)
|
We report a discovery of a new transient source, IGR J17331-2406 with the IBIS telescope onboard the INTEGRAL observatory. The source position is RA=17h33m08s and DEC=-24o06m46s (equinox 2000), with uncertainty ~2', that is about 40 arcmin from the known X-ray pulsar GX1+4.
The source was detected during the observations of the Galactic Center field performed between 31 Aug. and 5 Sept. 2004, with an average flux measured during the 4-5 Sept observations of 9.1+/-0.8 mCrab in the 18-60 keV energy range. The source was also marginally detected (4 sigma) in the 60-120 keV energy band. Its spectrum in the 20-80 keV energy band can be well described by a simple powerlaw with a photon index of ~1.8. A possible outburst was observed between UT 22:45 - 23:15 on Sept. 4. During this period the source flux increased up to ~30 mCrab in the 18-60 keV energy band.
We encourage follow up observations at various wavelengths.
|
2004-09-08 19:17:00
|
x-ray,gamma ray,pulsar,transient,request for observations
|
329
|
NTEGRAL discovered a new transient source IGRJ16465-4507
|
A. Lutovinov (IKI, Moscow), J. Rodrigues (ISDC, Versoix, CEA, Saclay), C. Budtz-Jorgensen (DSRI, Copenhagen), S. Grebenev (IKI, Moscow), C. Winkler (ESA/ESTEC, Noordwijk)
|
The new transient source IGRJ16465-4507 was detected with the ISGRI detector of the IBIS telescope of the INTEGRAL observatory on 6-7 Sept., 2004. The best position derived from our analysis is RA=16h46.5m and DEC=-45o07.5m (equinox 2000, preliminary uncertainty ~2.5'). IGR J16465-4507 is therefore ~16 arcmin from the INTEGRAL source IGR J16479-4514, which was also detected at the same time.
The new source was detected by IBIS/ISGRI with a flux of 8.8+/-0.9 mCrab in the 18-60 keV energy band. A strong flare with an average flux of ~28 mCrab in the same energy band was observed from the source on Sept. 7 UT 12:00. It then decayed back to the pre flare value after this episode.
We encourage follow up observations at various wavelengths.
|
2004-09-09 02:48:00
|
x-ray,transient,request for observations
|
330
|
Nova in M31
|
Tzenev L. (IA, Sofia), Georgiev I.(IA, Sofia), Ovcharov E. (SU, Sofia), Stanev I. (SU, Sofia), Georgiev Ts. (IA, Sofia), Nedialkov P. (SU, Sofia)
|
NOVA IN M31
We report the discovery of an apparent nova located at R.A. = 0h42m42s.77, Decl. = +41o15'44".4 (equinox 2000.0), which is 17".4 west and 44".0 south of the center of M31. Available B magnitude and B-V colour from CCD images taken with the 2m NAO Rozhen telescope, Bulgaria: Aug. 22.040 UT, 17.956+/-0.030; 0.122+/-0.065.
|
2004-09-11 21:41:00
|
optical,nova
|
331
|
INTEGRAL detects increased activity from 4U 0115+63
|
J. A. Zurita Heras (ISDC, Versoix), S. E. Shaw (Southampton; ISDC, Versoix), I. Kreykenbohm (IAA, Tubingen), P. Kretschmar (ISDC, Versoix; MPE, Garching), Diego Gotz (IASF, Milano), S. Mereghetti (IASF, Milano), A. Lutovinov (IKI, Moscow), G. Palumbo (Bologna), T. Oosterbroek (ESTEC, Noordwijk), C. Budtz-Jorgensen (DSRI, Copenhagen), P. Ubertini (IASF, Roma)
|
During a Galactic Plane Scan on September 12th 2004, the INTEGRAL gamma ray observatory detected the high mass X-ray binary 4U 0115+63. Increased activity was first noticed by the IBAS gamma ray burst detection software at 14:53 UTC, leading to the generation of three alerts (1978-79-80). The source was visible in the ISGRI field of view until 16:24 UTC.
The source was also visible in the JEM-X x-ray monitor in one Science window (2 ksec observation starting at 15:31 UTC) leading to the following estimated fluxes:
JEM-X: 3-10 keV ~500 mCrab; 10-30 keV ~750 mCrab ISGRI: 20-60 keV ~400 mCrab; 60-200 keV ~25 mCrab.
Those values correspond to an increase of a factor 10 to the fluxes reported in Atel#326 from Lutovinov et al. 14 days earlier.
Spectral extraction was possible from the JEM-X observation. No cyclotron line features were seen, although only a 2 ksec observation was available for JEM-X in this preliminary analysis.
Pulsed analysis of the ISGRI data, in the 15-40 keV band, clearly shows a periodic signal of 3.614 +/- 0.003 s, which is in agreement with published values and identifies the flux as being from the associated pulsar, PSR B0115+63.4.
|
2004-09-14 00:58:00
|
x-ray,gamma ray,binary,gamma-ray burst,pulsar
|
332
|
High activity of XTE J1743-363 detected with INTEGRAL
|
S. A. Grebenev (IKI, Moscow), R. A. Sunyaev (IKI, Moscow & MPA, Garching)
|
During INTEGRAL Open Program observations of the Galactic center region on Sept. 18-20, 2004, an X-ray transient was detected by IBIS/ISGRI with the S/N ratio of 9.5 at the position, R.A.= 17h43m00s, Dec.= -36d21m30s (equinox 2000.0, error radius 2') consistent with that of XTE J1743-363 (IAUC # 7120 ). The source was strongly variable with an average flux 10.0+/-1.1 mCrab in the 18-45 keV band.
XTE J1743-363 was discovered by RXTE in Feb. 1999 with the flux ranging from 3 to 15 mCrab in the 2-10 keV band. It was marginally (at the flux level of 1.7+/-0.2 mCrab) detected by IBIS/ISGRI in Sept. 2003 during our previous deep observations of the Galactic Center region (Revnivtsev et al., Astron. Lett., 2004, 30, 382). But INTEGRAL was unable to detected it during first-year Core Program observations and the source isn't present in the IBIS/ISGRI Galactic Plane Survey catalog by Bird et al. (ApJ, 2004, 607, L33).
We encourage follow-up observations of this source at all wavelengths.
|
2004-09-21 19:30:00
|
radio,infra-red,optical,x-ray,transient,variables
|
333
|
4U 0115+634 in outburst
|
J. Tueller, S. D. Barthelmy, H. Krimm, T. Okajima, S. Owens, P. Serlemitsos (NASA/Goddard Space Flight Center), A. Furuzawa, Y. Ogasaka, R. Shibata, K. Tamura, Y. Tawara, K. Yamashita (Nagoya Univ.), H. Kunieda JAXA/ISAS, M. Rex (U of Penn.)
|
The balloon-borne hard X-ray focusing telescope, InFOCuS, a collaboration between NASA/GSFC, Nagoya University, JAXA/ISAS and the University of Pennsylvania, observed transient X-ray pulsar 4U 0115+634. The pulsar is continuing in outburst as first detected by RXTE/ASM (http://xte.mit.edu/XTE.hmtl) during its observation from Aug. 27 to Sept. 2. InFOCuS was launched by NSBF from Ft. Sumner NM on Sept. 16 and observed 4U 0115+634 for 3.2 ksec starting at 4.6 hrs UT on Sept. 17 The time period from 4.7 to 5.25 hrs UT on Sept. 17 was used to derive the preliminary flux of (3.18 +0.375 -0.324) x 10**-9 erg cm**-2 s**-1 in the 20 to 50 keV range. This flux is consistent with the RXTE/ASM observation. A summed epoch analysis was performed and the preliminary pulse period is 3.616 +/- 0.001 sec. Further analysis is in process.
|
2004-09-24 01:18:00
|
x-ray,gamma ray,binary,neutron star,pulsar,star,transient
|
334
|
NOVA NEAR THE CENTER OF M31
|
Tzenev L. (IA, Sofia), Georgiev I.(IA, Sofia), Ovcharov E. (SU, Sofia), Stanev I.(SU, Sofia), Kostov A. (IA, Sofia), Georgiev Ts. (IA, Sofia), Nedialkov P. (SU, Sofia)
|
NOVA NEAR THE CENTER OF M31
We report the discovery of an apparent nova located at R.A. = 0h42m44s.45, Decl. = +41o16'10".5 (equinox 2000.0), which is only 1".6 east and 1".1 north of the center of M31. Available B magnitude and B-V colour from CCD images taken with the 2m NAO Rozhen telescope, Bulgaria: Sept. 16.097 UT, 15.51+/-0.05; 0.83+/-0.10.
|
2004-09-25 12:14:00
|
optical,nova
|
335
|
Radio observations of XTE J1743-363
|
M. P. Rupen, V. Dhawan, A. J. Mioduszewski (NRAO)
|
Very Large Array (VLA) observations of the currently active X-ray source XTE J1743-363 (ATEL #332) on 24 September 2004 showed no strong sources at either 4.9 GHz (rms 84 microJy/beam) or 8.5 GHz (rms 155 microJy/beam) within the 2 arcminute INTEGRAL error circle. The only strong source is a 1.5 mJy source (uncorrected for primary beam attenuation) at 4.9 GHz, about 6.8 arcmin from the nominal INTEGRAL position.
The min/max within the INTEGRAL error circle are (-0.45/+0.38 mJy/beam) at 4.9 GHz, and (-0.40/+0.44 mJy/beam) at 8.5 GHz. The latter peak is the strongest point in a 5.5x5.5 arcmin image; its position (J2000) is
B. Monard has reported a possible optical/IR counterpart in VSNet. The VLA data show a possible (3sigma) counterpart to this source at 4.9 GHz (flux density 260 +/- 84 microJy/beam), at (J2000)
These data were taken in spectral line mode to avoid bandwidth smearing, but the numbers reported here have not been corrected for the primary beam response. This means that the apparent rms noise is constant across the map, but sources near or beyond the half-power point (radius of about 4.5 arcmin at 4.9 GHz and 2.7 arcmin at 8.5 GHz, centered on the INTEGRAL position) will appear fainter than they actually are.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
|
2004-09-27 03:15:00
|
radio,infra-red,optical,x-ray,binary,black hole,neutron star,star,transient,variables
|
336
|
IGR J16465-4507 counterpart
|
Juan A. Zurita Heras (ISDC), Roland Walter (ISDC)
|
XMM-Newton follow-up observation of the transient source IGR J16465-4507 detected by INTEGRAL on Sept. 6, 2004 (ATEL#329) was performed on Sept. 14, 2004 (02:16-04:45 UTC). A single counterpart is detected with the EPIC/MOS camera at position RA=16:46:35.5 DEC=-45:07:04 (J2000, uncertainty 4").
The X-ray flux (3+/-1)E-12 erg/sec/cm2 (4-10 keV) is about 100 times fainter than during the flare detected by INTEGRAL on Sept. 7.
A bright infrared counterpart (2MASS J16463526-4507045, J=10.54) is found in the 2MASS catalogue.
|
2004-10-02 02:57:00
|
x-ray,gamma ray,transient
|
337
|
4U 0115+63 Observations with RXTE
|
W. Coburn, E. Kalemci (UCB); P. Kretschmar (MPE/ISDC); I. Kreykenbohm (IAAT/ISDC); R. Rothschild (UCSD); R. Staubert (IAAT); J. Wilms (Warwick)
|
On MJD 53270.382 we observed the source 4U 0115+63 during outburst for ~20 ks with RXTE. The 2-10 keV flux during the observation was (6.75 +/- 0.06)x10**-9 ergs cm**-2 s**-1. Our preliminary analysis of the joint PCA/HEXTE phase averaged spectrum indicates the presence of the known ~12 keV cyclotron line, along with upwards of 4 approximately harmonically spaced higher harmonics. This is similar to what was seen in the 1999 outburst. There is also a clear QPO in the lightcurve, with individual cycles varying from the average by as much as 45%. The QPO in the power spectrum peaks at ~4.5 mHz, with a ~1 mHz FWHM. This is similar to the ~2 mHz QPO observed in this source in 1999, and a mHz frequency QPO is probably a ubiquitous feature of this source during outburst.
|
2004-10-02 05:30:00
|
x-ray,binary,neutron star,star
|
338
|
Circumstantial evidence for a blue supergiant companion of IGR J16465-4507
|
D. M. Smith (Physics Department and Santa Cruz Institute for Particle Physics, U. C. Santa Cruz)
|
The 2MASS counterpart to IGR J16465-4507 (ATEL #329) identified by Heras and Walter (ATEL #336) is also a bright star in the USNO B1.0 catalog, 0448-0520455, with the magnitudes shown in the table below. Its short outburst and high duty cycle of quiescence suggest a similarity with the systems XTE J1739-302 (ATEL #181,#182,#184,#186,#218) and IGR J17544-2619/1RXS J175428.3-262035 (ATEL #190,#191,#192,#194,#252, IAUC # 8202 ). The former is known from optical and infrared spectroscopy to have a supergiant companion of spectral type O7.5Iaf or O8Iaf (I. Negueruela et al., in preparation), and the latter also has a blue supergiant companion (S. Chaty et al., in preparation). The photometry of all three sources from USNO B1.0 and 2MASS also suggests they may all be similar. Taking canonical values of R, B, and K for an O9I supergiant and the relations between interstellar absorption in these bands from Cox (Allen's Astrophysical Quantities, 4th Edition, AIP Press, 2000), I find the following parameters for each system:
Name USNO B1.0USNO B1.02MASSB ExtinctionDistanceK Excess B2 R2 K (Ab, mag.) (kpc) (K mag.) XTE J1739-302 17.0 12.9 7.43 11.1 3.3 0.5 IGR J17544-2619 13.9 11.9 8.02 6.0 8.5 1.5 IGR J16465-4507 15.2 13.0 9.84 6.5 12.5 0.5
All three systems show an infrared excess beyond the expectation for this spectral type, which may be related to the local material which creates high x-ray absorption in XTE J1739-302 and IGR J17544-2619 at least. The derived columns are somewhat sensitive to the exact spectral class assumed and to differences between magnitudes from the first and second epochs in the USNO B1.0 catalog (I have used the second epoch throughout for consistency). More precise values will await higher-quality photometry as well as detailed spectroscopy on all systems. The large distance to IGR J16465-4507 and an early-type companion are consistent with its small Galactic latitude (0.13 degrees).
It is interesting to note that two very bright, persistent binaries with blue supergiant companions also show extremely fast outbursts lasting on the order of hours: Cyg X-1, a black-hole binary with a companion of type O9.7Iab (Golenetskii et al. 2003, ApJ 596, 1113), and Vela X-1, an x-ray pulsar with a companion of type B0.5Iab (Krivonos et al. 2003, ATEL #211). Fast transient outbursts may be a hallmark of systems with blue supergiant secondaries, perhaps due either to the short viscous timescale in small accretion disks associated with wind accretion, or to some kind of brief ejection intrinsic to the secondaries.
I am grateful to I. Negueruela and S. Chaty for permission to mention their upcoming results on the other two systems.
|
2004-10-06 06:41:00
|
infra-red,optical,x-ray,binary,pulsar,star,transient
|
339
|
he likely optical counterpart to the X-ray transient IGR J01363+6610
|
FORTH & University of Crete
|
We report photometric and spectroscopic optical observations of the likely optical counterpart to the X-ray transient IGR J01363+6610 discovered by INTEGRAL (Grebenev et al., ATel 275). The photometric and red-end spectroscopic observations were made from the 1.3-m telescope of the Skinakas Observatory (Crete, Greece), while blue-end spectra were obtained using the NOT 2.56m telescope at El Roque de los Muchachos Observatory (La Palma, Spain).
The observations revealed that the star located at R.A.= 01h35m50s, Decl.=66d12m40s, consistent with the INTEGRAL uncertainty circle, shows a very strong Halpha emission. Measured photometric magnitudes are B=14.68+-0.02, V=13.29+-0.03, R=12.32+-0.03 and I=11.37+-0.04 (JD 2,453,214.55) and the Halpha equivalent width is -50+-2 amstrongs (JD 2,453,193.52). The classification spectrum (4000-5000 Amstrongs) shows the presence of Hbeta and Hgamma in emission and the metallic and HeI lines typical of an early B-type star of low luminosity. The spectral type is close to B1, typical of a Be/X-ray binary. This object is very probably identical with the catalogued emission line star [KW97] 6-30 (Kohoutek & Wehmeyer, 1999, A&AS, 134, 255), though the coordinates listed in this catalogue locate the source about 4 arcmin away and outside the INTEGRAL error circle.
If the identification is correct then the early-type optical companion, the presence of Balmer emission lines and the lack of radio emission (Pooley, ATel 276) suggests that IGR J01363+6610 is a new Be/X-ray binary. The detections of X-ray pulsations would provide the final proof of its nature.
|
2004-10-08 20:55:00
|
radio,optical,x-ray,binary,neutron star,star,transient
|
340
|
INTEGRAL discovery of a possible new source IGR J18410-0535
|
J. Rodriguez (CEA, Saclay & ISDC Versoix), A. Domingo Garau (LAEFF, Vilspa), S. Grebenev (IKI, Moscow), A. Parmard (ESTEC, Noordwijk), J.-P. Roques (CESR, Toulouse), V. Schonfelder (MPE, Garching), P. Ubertini (IASF, Roma), R. Walter (ISDC, Versoix), N.-J. Westergaard (DSRI, Copenhagen)
|
We report on the detection of a possible new source with the IBIS/ISGRI detector aboard the INTEGRAL observatory. The source, IGR J18410-0535, was discovered during Galactic Plane Deep Exposure, on October 8 2004 ~7h50 UTC, as it was undergoing a ~70 mCrab flare (integrated over 1700 s) in the 20-60 keV energy range, and 20 mCrab in the 60-200 keV range. The source was also detected in two subsequent INTEGRAL pointings, although only between 20 and 60 kev with a flux roughly half that of the peak one. The best position obtained with ISGRI is RA = 18h 41.0m, DEC.= 05deg 35 arcmin (+- 2 arcmin at 90%).
|
2004-10-09 00:18:00
|
x-ray,gamma ray,binary,black hole,neutron star,pulsar,star,transient,request for observations
|
341
|
IGR J18410-0535 = AX J1841.0-0536 ?
|
J. P. Halpern, E. V. Gotthelf (Columbia U.)
|
We note that the INTEGRAL source IGR J18410-0535 reported by Rodriguez et al. (ATEL #340) is possibly an outburst of the transient 4.74 s X-ray pulsar AX J1841.0-0536, which in turn was identified using Chandra with a Be star counterpart at coordinates (J2000) 18h41m00.43s, -05d35'46.5" (Halpern et al., ATEL #289). The source positions are in agreement, and the Chandra image shows no other source within 2' of the INTEGRAL position. Prompt X-ray follow-up of this transient Be/X-ray binary pulsar in outburst is encouraged.
|
2004-10-09 07:08:00
|
optical,x-ray,gamma ray,binary,neutron star,pulsar,star,transient
|
342
|
New X-ray transient IGR J17507-2856 discovered with INTEGRAL
|
S. A. Grebenev (IKI, Moscow), R. A. Sunyaev (IKI, Moscow; MPA, Garching)
|
We report on the discovery with INTEGRAL of a new X-ray source 1.3 deg off the Galactic center. This source, IGR J17507-2856, was detected with IBIS/ISGRI on Sept. 18-23, 2004, during Open Program observations of the region. The S/N ratio was 6.9 in the 18-45 keV mosaic image, the corresponding average flux was 2.98+/-0.43 mCrab. The source was also seen during individual revolutions (on a scale of 3 days) at the S/N ratio level of 4.5-5.0
The best fit position, R.A.= 17h50m44s, Dec.= -28d56m17s (equinox 2000.0, error radius 2') keeps the source outside error boxes of the nearby known sources: the transient X-ray burster SAX J1750.8-2900 (R.A.=17h50m24s, Dec.=-29d02m18s, 90%-error radius 1', Natalucci et al., ApJ, 1999, 523, L45; offset 7.5') and the soft X-ray source 1RXP J175029-2859.9 = AX J1750.5-2900 (error radius 0.1'; offset 4.9')
. The source was marginally detected again on Oct. 3-5 during next INTEGRAL observations (dedicated to the Galactic Center Deep Exposure). We encourage follow-up observations of this source at all wavelengths.
|
2004-10-11 19:11:00
|
radio,far-infra-red,infra-red,x-ray,black hole,neutron star,star,transient
|
343
|
The likely optical counterpart to the X-ray transient IGR J01363+6610 (Resubmission of ATel#339)
|
Pablo Reig (FORTH & University of Crete), Ignacio Negueruela (University of Alicante, Spain), Antonis Manousakis (University of Crete), Amparo Marco (University of Alicante) and Giannis Papamastorakis (University of Crete)
|
After the submission of ATel #339 a few formatting inconsistencies and some missing/incorrect information were spotted. This is the corrected version of ATel #339. It also contains new information concerning the association of the proposed counterpart with the Halpha emission line star [KW97] 6-30.
We report photometric and spectroscopic optical observations of the likely optical counterpart to the X-ray transient IGR J01363+6610 discovered by INTEGRAL (Grebenev et al., ATel #275). The photometric and red-end spectroscopic observations were made from the 1.3-m telescope of the Skinakas Observatory (Crete, Greece), while blue-end spectra were obtained using the NOT 2.56m telescope at El Roque de los Muchachos Observatory (La Palma, Spain).
The observations revealed that the star located at R.A.= 01h35m50s, Decl.=66d12m40s, consistent with the INTEGRAL uncertainty circle, shows a very strong Halpha emission. Measured photometric magnitudes are B=14.68+-0.02, V=13.29+-0.03, R=12.32+-0.03 and I=11.37+-0.04 (JD 2,453,214.55) and the Halpha equivalent width is -50+-2 Anstrongs (JD 2,453,193.52). The classification spectrum (4000-5000 Anstrongs) shows the presence of Hbeta and Hgamma in emission and the metallic and HeI lines typical of an early B-type star of low luminosity. The spectral type is close to B1, typical of a Be/X-ray binary. This object is probably identical with the catalogued emission line star [KW97] 6-30 (Kohoutek & Wehmeyer, 1999, A&AS, 134, 255), though the coordinates listed in this catalogue locate the source about 2 arcmin south-west of our proposed candidate and outside the INTEGRAL error circle. It was brought to our attention by Brian Skiff (Lowell Observatory) that the catalogued Halpha emission line star might as well be TYC 4043- 860-1 at R.A.= 01h36m06.79s, DEC=+66h13m02.6s (J2000), i.e, ~1.5 arcmin east of our observed star. This star has V=11.5 and was observed by Gonzalez & Gonzalez (1956, Bol. Obs. Tonantz. Tacub., 2, part no 15, 16-26). However, this star is not presently active. A slitless spectrum obtained with the NOT (JD 2,453,282.5) shows Halpha in absorption. Likewise, our photometric value through a narrow Halpha filter (JD 2,453,186.56) is comparable to those of other field stars.
If our identification is correct then the early-type optical companion, the presence of Balmer emission lines and the lack of radio emission (Pooley, ATel #276) suggests that IGR J01363+6610 is a new Be/X-ray binary. The detections of X-ray pulsations would provide the final proof of its nature.
|
2004-10-12 17:47:00
|
radio,optical,x-ray,binary,neutron star,star,transient
|
344
|
Optical/IR Candidates for XTE J1829-098
|
J. P. Halpern, E. V. Gotthelf (Columbia U.)
|
A very bright star in the 2MASS survey should be considered a possible supergiant companion of the transient 7.8 s pulsar XTE J1829-098 (Markwardt et al., ATEL #317; Halpern & Gotthelf, ATEL #319). At coordinates (J2000) R.A. = 18h29m44.55s, Decl. = -09d51m20.3s, this candidate has R>21, I=14.4, J=8.04, H=6.11, K=4.98, where the R and I magnitudes are estimated from digitized UK Schmidt sky-survey plates. Although its coordinates are 8" from the XMM-Newton position of the source (J2000) R.A. = 18h29m44.06s, Decl. = -09d51m23.3s as reported in ATEL #319, i.e., twice the nominal X-ray error, allowance could be made for the off-axis location in the X-ray image and absence of other identified sources for astrometric alignment. Alternatively, there is a USNO-B1.0 and 2MASS star at coordinates (J2000) R.A. = 18h29m44.28s, Decl. = -09d51m26.8s, which is 5" from the X-ray position. This candidate has B=21.44, R=17.40, I=15.20, J=12.46, H=10.54, K=9.67. IR/optical spectroscopy to classify both of these candidate counterparts should be obtained.
|
2004-10-13 07:34:00
|
infra-red,optical,x-ray,binary,neutron star,pulsar,star,transient
|
345
|
Flares from a new Integral hard X-ray source, IGR J17407-2808, likely associated with the ROSAT source SBM 10
|
P. Kretschmar (MPE/ISDC, Versoix), S. Mereghetti (IASF, Milano), W. Hermsen (SRON, Utrecht), P. Ubertini (IASF, Roma), C. Winkler (ESTEC, Nordwijk), S. Brandt (DSRI, Copenhagen), R. Diehl (MPE, Garching)
|
On Oct 9, 2004 Integral observed hard X-ray flares from a source located at R.A.=17h 40.7m, Dec.=-28s 08' (J2000, error radius 2.3').
This new hard X-ray source, IGR J17407-2808, is positionally coincident with a faint ROSAT source listed as no. 10 in the catalogue of sources in the Galactic Center region by Sidoli, Belloni & Mereghetti 2001, A&A 368, 835 and as 2RXP J174040.9-280852 in the ROSAT Source Browser. No other observations of [SBM2001] 10 have been published up to date.
The flares were observed with the IBIS instrument in the 20-60 keV energy range, starting at MJD 53287.6310 and over a timespan of 2000 seconds finishing in a strong flare at MJD 53287.6327. Before and after this time period the source was not detected.
The last flare, with peak fluxes of 0.8±0.1 Crab and 0.6±0.1 Crab in the energy ranges 20-40 keV and 40-60 keV respectively, triggered an automatic alert message of the Integral Burst Alert System (IBAS Alert #2010) which led to the discovery of the source (Gotz et al., GCN Circ. #2793). The source was outside the FOV of the JEM-X and OMC monitor instruments during this flare.
Note that the position of J17407-2808 is inconsistent with that of the X-ray burster SLX 1737-282 [AX J1740.7-2818] (in't Zand et al. 2002, A&A 389, L43), which is just ~11 arcmin away. The correct Integral attitude is confirmed by other bright sources in the FOV.
|
2004-10-14 22:14:00
|
x-ray,gamma ray,transient
|
346
|
Nova in M31
|
Tzenev L. (IA, Sofia), Ovcharov E. (SU, Sofia), Stanev I. (SU, Sofia), Georgiev Ts. (IA, Sofia), Georgiev I. (IA, Sofia), Nedialkov P. (SU, Sofia)
|
We report the discovery of an apparent nova located at R.A. = 0h42m51s.98, Decl. = +41o16'20".8, which is 1'55".1 east and 11".4 north of the center of M31. Available B magnitude and B-V colour from CCD images taken with the 2m NAO Rozhen telescope, Bulgaria: Sept. 9.896 UT, 19.11+/-0.05; -0.39+/-0.10.
|
2004-10-15 00:58:00
|
optical,nova
|
347
|
The Orbital Period of the SMC X-ray Pulsar XTE J0055-727
|
R. H.D. Corbet (NASA/GSFC and USRA), C. B. Markwardt (NASA/GSFC and University of Maryland), F. E. Marshall (NASA/GSFC), M. J. Coe, W. R.T. Edge, J. L. Galache (Southampton University), S. Laycock (CfA)
|
Regular monitoring of the Small Magellanic Cloud with the RXTE Proportional Counter Array has revealed a periodicity in the pulsed flux from the 18.4s X-ray pulsar XTE J0055-727, initially found to be active in November/December 2003 (Corbet et al. 2003, ATEL #214). The source was then not detected in weekly monitoring of the SMC until seen to be active on May 21. The source was then next detected on: June 23, July 29, September 1, and October 7. This series of five detections can be described by an ephemeris of: T = MJD 53145 +/- 3 + n x 34.8 +/- 1.1 where T is the epoch of outburst and n is the outburst cycle number. For the purposes of determining this outburst recurrence period we ascribed an error of +/- 3.5 days to each detection because of our weekly sampling intervals.
This regular pattern of outbursts strongly suggests that they show the orbital period of this system. This combination of pulse and orbital periods is consistent with XTE J0055-727 being a Be star system (Corbet 1986, MNRAS, 220, 1047).
The first source detections in 2003 bracket the time of a predicted outburst and, if included in our analysis, the ephemeris of predicted outburst becomes: T = MJD 53145.7 +/- 1.3 + n x 34.6 +/- 0.4
A plot showing the difference between predicted and observed times of source detection is available at: http://lheawww.gsfc.nasa.gov/users/corbet/pulsars/18.37omc.ps
We encourage observations with imaging X-ray instruments and in other wavebands at the times of future predicted outburst which may lead to an identification of the optical counterpart.
|
2004-10-16 04:58:00
|
optical,x-ray,binary,neutron star,pulsar,star,transient
|
348
|
Radio Observations of SNe 2004dx and 2004eh
|
A. M. Soderberg (Caltech), D. A. Frail (NRAO) and S. R. Kulkarni (Caltech)
|
We observed the optical position of Type Ibc SNe 2004dx (IAUC # 8392 ) and 2004eh (IAUC # 8401 ) on 2004 October 28.2 UT with the Very Large Array. We do not detect a radio counterpart to either supernova and place 2-sigma limits of 78 and 48 microJy for SN2004dx and SN2004eh, respectively.
|
2004-10-29 06:29:00
|
radio,optical,supernovae
|
349
|
Transient Pulsar V0332+53 in Outburst
|
J Swank(NASA/GSFC), R. Remillard(MIT), E. Smith (NASA/GSFC)
|
The 4.4 s pulsar V0332+53 in the 34.2 d binary with BQ Cam averaged 142 +/- 6 mCrab as seen with the RXTE ASM on MJD 53337 (Nov. 28). In 1-day ASM bins (production data), the first ASM detection of the current outburst occured on MJD 53332, when the average flux (2-12 keV) was 22 +/- 4 mCrab. A similar flux was seen the following day, but then the source jumped to 68 +/- 5 mCrab on MJD 53334 (Nov. 25). The ASM sees a hard spectrum (HR2 = 2.6), which is typical for accretion-powered X-ray pulsars. A brief (6 minute) observation with the PCA on Nov. 27 found an average 2-10 kev flux of 216 mCrab and strong variability. The ASM quicklook rates suggest a possible leveling off, by comparison.
This outburst was predicted, based on optical brightening in January, 2004, by V. Goranskij and E. Barsukova(ATEL # 245).
Additional, long PCA/HEXTE observations are planned.
|
2004-11-29 22:13:00
|
optical,x-ray,binary,pulsar,transient,request for observations
|
350
|
New X-ray transient IGR J11435-6109 discovered with INTEGRAL
|
S. A.Grebenev (IKI, Moscow), P. Ubertini (IASF, Roma), J. Chenevez (DSRI, Kopenhagen), N. Mowlavi (ISDC, Versoix), J.-P. Roques (CESR, Toulouse), N. Gehrels (NASA/GSFC, Greenbelt), E. Kuulkers (ESTEC, Noordwijk)
|
A new hard X-ray transient, IGR J11435-6109, was discovered with the IBIS/ISGRI telescope on board INTEGRAL on Nov. 23, 2004, during observations (3 successive pointings at 12:30-14:20 UTC) dedicated to the Galactic Plane Scan. The source was located 1 deg off the known X-ray pulsar twins, 4U1145-619 and 1E1145.1-6141, at the position, R.A.= 11h43m52s, Dec.= -61d09m00s (equinox 2000.0, error radius 2.5'), generally consistent with that of the faint ROSAT source 1RXS J114358.1-610736. The S/N ratio was 9.5 in the 18-45 keV mosaic image, the corresponding average flux was equal to 18+/-2 mCrab.
The source was also detected in the standard X-ray band with the JEM-X telescope during one of the pointings. This detection as well as the possible association of IGR J11435-6109 with 1RXS J114358.1-610736 let us to suggest that it differs from the main population of (strongly photoabsorbed) new INTEGRAL sources.
We encourage follow-up observations of this source at all wavelengths.
|
2004-11-30 00:06:00
|
radio,infra-red,optical,x-ray,binary,black hole,neutron star,pulsar,star,transient,request for observations
|
351
|
Radio Observations of SN2004gk
|
A. M. Soderberg, S. R. Kulkarni (Caltech) and D. A. Frail (NRAO)
|
We observed the Type Ic SN2004gk (IAUC # 8446 ) with the Very Large Array at 8.5 GHz on 2004 Nov 30.57 UT. We do not detect radio emission from the supernova and place a 2-sigma limit of 0.10 mJy at the optical position. Assuming a distance of 15 Mpc to the SN host galaxy (IC 3311), this VLA observation implies an upper limit on the SN2004gk radio luminosity of ~ 10^25 erg/s/Hz, making it four orders of magnitude less radio luminous than SN1998bw and comparable to SN2002ap at a similar epoch.
|
2004-12-01 07:23:00
|
radio,optical,supernovae
|
352
|
IGR J00291+5934, a new X-ray transient discovered with INTEGRAL
|
D. Eckert, R. Walter (ISDC, Versoix, Switzerland), P. Kretschmar (MPE, Garching, Germany), M. Mas-Hesse (LAEFF, Madrid, Spain), G. G.C Palumbo (University di Bologna, Italy), J.-P. Roques (CESR, Toulouse, France), P. Ubertini (IASF, Roma, Italy), C. Winkler (ESTEC, Noordwijk, The Netherlands)
|
A new transient X-ray source was discovered with the IBIS/ISGRI and JEM-X detectors on board INTEGRAL on Dec. 2, 2004, during 3 successive pointings dedicated to the Galactic Plane Scan. The source was located with both ISGRI and JEM-X at R.A.= 00h 29.1', Dec.= +59d 34m, (equinox 2000.0) with an error radius of 1.5'. This position is about 20 arcmin off the cataclysmic variable V* V709 Cas and 0.5 degrees off 4U 0027+59. The S/N ratio was 21 in the ISGRI 20-60 keV band. The corresponding average flux is 55+/-5 mCrab. The source flux measured in each of the successive pointings remained constant within 20%. JEM-X detected the source in the 3-10 keV band during the only pointing in which the source was in its field of view, with a flux of 23+/-5 mCrab. The source will be in the field of view of INTEGRAL again on Dec. 5, 2004 for about 2 days for an open program observation. We encourage follow-up observations of this source at all wavelengths.
|
2004-12-03 19:01:00
|
x-ray,gamma ray,binary,black hole,cataclysmic variable,neutron star,pulsar,star,transient,variables
|
353
|
IGR J00291+5934 is a 598 Hz X-ray Pulsar
|
C. B. Markwardt (U. Maryland and GSFC), J. H. Swank (GSFC), T. E. Strohmayer (GSFC)
|
IGR J00291+5934 (Eckert et al. 2004, ATel #352) was observed by the RXTE PCA instrument on Dec. 3, 2004 at 06:17 (UTC) for approximately 2000 seconds exposure. The source was detected with a flux of 35 mCrab (2-10 keV).
Pulsations were detected at a barycentric frequency of 598.88 Hz, with a pulsed amplitude of approximately 6%. There is no evidence of any harmonics at half or double this frequency, suggesting that it is the fundamental rotation period of a neutron star. During the 2 ks observation the frequency drifts by approximately 36 mHz, in a manner consistent with Doppler orbital modulation. The suggested orbital period is in the 2-4 hour range, with an a_x sin(i) value of 50-100 lt-ms. IGR J00291+5934 appears to be the fastest known X-ray millisecond pulsar system.
The X-ray spectrum is consistent with an absorbed power law, with photon index 1.7 and absorption column n_H = 7e21 cm-2. The fluxes in the 2-10 and 10-40 keV X-ray bands are 6.1e-10 and 9.2e-10 erg s-1 cm-2.
Significant low frequency variability is also detected, consistent with approximate f^{-0.45} noise, with a total amplitude from 1 mHz to 1 Hz of 18%.
XTE is planning more observations to occur as soon as possible.
|
2004-12-05 04:29:00
|
x-ray,binary,neutron star,pulsar,star,transient
|
354
|
IGR J00291+5934 Optical Counterpart
|
Derek B. Fox and S. R. Kulkarni (Caltech)
|
We have observed the localization of the Integral transient IGR J00291+5934 (ATEL #352) with the Robotic Palomar 60-inch Telescope, in seven 120-s R-band exposures extending from 05:59 to 06:15 UT on 4 December 2004. Comparison of our images to the Digitized Sky Survey reveals the presence of a single new, bright, stationary, point-like object within the localization region, at coordinates RA 00:29:03.06, Dec +59:34:19.0 (J2000), with estimated coordinate uncertainty of less than 0.5". The brightness of the counterpart, by reference to a single nearby Guide Star Catalog object, is estimated to be R ~ 17.4 mag. We tentatively identify this object as the optical counterpart of IGR J00291+5934. Images and a finding chart for the candidate may be found at: http://www.astro.caltech.edu/~derekfox/igrj00291+5934/.
|
2004-12-05 04:20:00
|
optical,x-ray,binary,neutron star,pulsar,star,transient
|
355
|
IGR J00291+5934 - radio observation
|
Guy Pooley (MRAO, Cavendish Lab, Cambridge UK)
|
An observation of IGR J00291+5934 (ATEL #352) with 5 antennas of the Ryle Telescope, Cambridge, UK at 15 GHz resulted in a probable detection at 1.1 mJy. The observation was for 5 hours from 2004 Dec 04 17h10m, and was centred on the original position from the INTEGRAL satellite. The detection was the strongest signal in the field which was mapped (6 arcmin FWHM) was 104 arcsec from the pointing centre and was 12 arcsec from the optical position (ATEL #353); the resolution of the telescope in this mode is about 25 arcsec. The signal/noise ratio is about 3.5. A further observation is in progress.
|
2004-12-06 00:11:00
|
radio,optical,x-ray,transient
|
356
|
Spectroscopic observations of the counterpart of IGR J00291+5934
|
G. Roelofs (Univ. of Nijmegen), P. G. Jonker, D. Steeghs, M. Torres (CfA), G. Nelemans (Univ. of Nijmegen)
|
Spectroscopic observations of the optical counterpart of the millisecond X-ray pulsar IGR J00291+5934 (Atel #352, 353) reported in an Atel by Fox & Kulkarni were obtained (Dec 5 00:29-01:15 UT) with the ISIS spectrograph mounted on the 4.2m William Herschel Telescope on La Palma. Weather conditions were not optimal with a seeing of ~2" and thin clouds. The spectra show weak evidence for broad emission line features near the HeII line at 4686 Angstrom and near the Halpha line at 6563 Angstrom. This further supports the identification of the proposed source as the optical counterpart of IGR J00291+5934.
|
2004-12-06 03:11:00
|
optical,x-ray,binary,neutron star,pulsar,star,transient
|
357
|
ASM Observations of IGR J00291+5934
|
Ron Remillard (for ASM team at MIT and GSFC)
|
A mission-long light curve (Jan. 1996 - Dec. 2004) has been constructed for IGR J00291+5934 (Atel #352),using the position of the optical counterpart (Atel #354). The results quoted below utilize only the dwells for which the fitted channel-A background has values less than 12.0 c/s. For the current outburst, the first ASM detection appears on 2004 Dec. 2, with an average flux of 20(4) mCrab at 2-12 keV. Then during Dec. 3-6, the average flux per day (UT) varies between 10(2) and 22(2) mCrab. There are marginal ASM detections (5 sigma) of similar outbursts from this source during 1998 Nov. 26-28 (maximum at 21(4) mCrab) and 2001 Sept. 11-21 (maximum at 18(3) mCrab). If these results are correct, then this transient appears every three years, and observers should note that the current outburst may not last much longer.
|
2004-12-07 00:59:00
|
optical,x-ray,pulsar,transient
|
358
|
Another X-Ray Brightening of H 1743-322 = IGR J1746-3213
|
J. H. Swank(GSFC) and C. B. Markwardt (U. Maryland and GSFC)
|
On Dec. 4, 2004 at 03:42 UT RXTE observed the source IGR J11435-6109 that was recently discovered with INTEGRAL's IBIS/ISGRI. (ATEL #350). The pointing position was offset to insure no contribution in the PCA from nearby 4U 1145-619 and 1E1145.1-6141. An average net count rate of 1.7/s was observed over 896 s. Variations of about 50% were notable, which could be due to a noisy pulsation. In a Lomb Scargle Periodogram, the strongest peak is at 166 s (and thus the data included only 5 periods). The spectral data were fit with an absorbed power law with a column density < 1e23 cm-2 (3 sigma) and a photon index of 2.3+/-0.4. The implied fluxes were 4.0e-11 and 1.6e-11 ergs cm-2 s-1 for 2-10 and 10-20 keV respectively. The source was an order of magnitude fainter than reported by Grebenev et al. on Nov. 23, 2004 (ATEL #350).
RXTE cannot make additional observations of the source at this time.
|
2004-12-07 10:33:00
|
x-ray,pulsar,transient,request for observations
|
359
|
IGR J11435-6109: Faded, but Variable - Possibly ~ 166 s Pulsations
|
J. H. Swank(GSFC) and C. B. Markwardt(U Maryland and GSFC)
|
The title of ATEL #358 was a product of submission error. Please ignore.
On Dec. 4, 2004 at 03:42 UT RXTE observed the source IGR J11435-6109 that was recently discovered with INTEGRAL's IBIS/ISGRI. (ATEL #350). The pointing position was offset to insure no contribution in the PCA from nearby 4U 1145-619 and 1E1145.1-6141. An average net count rate of 1.7/s was observed over 896 s. Variations of about 50% were notable, which could be due to a noisy pulsation. In a Lomb Scargle Periodogram, the strongest peak is at 166 s (and thus the data included only 5 periods). The spectral data were fit with an absorbed power law with a column density < 1e23 cm-2 (3 sigma) and a photon index of 2.3+/-0.4. The implied fluxes were 4.0e-11 and 1.6e-11 ergs cm-2 s-1 for 2-10 and 10-20 keV respectively. The source was an order of magnitude fainter than reported by Grebenev et al. on Nov. 23, 2004 (ATEL #350).
RXTE cannot make additional observations of the source at this time.
|
2004-12-07 11:04:00
|
x-ray,binary,pulsar,transient,variables
|
360
|
Orbit Solution for the Millisecond Pulsar IGR J00291+5934
|
C. B. Markwardt (U. Maryland & GSFC), D. K. Galloway (MIT), D. Chakrabarty (MIT), E. H. Morgan (MIT), T. E. Strohmayer (GSFC)
|
The INTEGRAL Transient IGR J00291+5934 (ATEL #352), now known to be a 1.67 millisecond X-ray pulsar (ATEL #353), was observed by the RXTE PCA on Dec 5 and 6. The source has decayed to approximately 27 mCrab (2-10 keV).
The data were barycentered using the Fox & Kulkarni optical counterpart position (ATEL #354). Pulsations with a sinusoidal frequency modulation are clearly detected in each observation. The best fitting orbit has a period of 147.412 +/- 0.006 min and an a_x sin(i) of 65.0 +/- 0.2 lt-ms. The mass function is 2.81e-5 +/- 0.02e-5 M_sun. Assuming a neutron star of mass 1.4 M_sun, the companion mass must be larger than 0.038 M_sun.
The orbit and inferred companion of IGR J00291+5934 appear to be very similar to that of SAX J1808.4-3658, the first known millisecond X-ray pulsar.
There is presently no evidence of X-ray eclipses or X-ray bursts.
RXTE continues to observe the source.
|
2004-12-07 11:07:00
|
optical,x-ray,binary,neutron star,pulsar,star,the sun,transient
|
361
|
The radio counterpart of IGR J00291+5934
|
Rob Fender (Southampton), Ger de Bruyn (ASTRON / Groningen),Guy Pooley (MRAO Cambridge), Ben Stappers (ASTRON)
|
We report further observations of the proposed radio counterpart to the accreting millisecond X-ray pulsar IGR J00291+5934.
Following the report of a possible ~1.1 mJy radio counterpart at 15 GHz on 2004 Dec 4 (ATEL #355), further observations with the Ryle Telescope (12 hr from 2004 Dec 05 13h41m UT) did not detect the source with a 3-sigma upper limit of ~0.6 mJy.
A ~10hr observation with the Westerbork Synthesis Radio Telescope (WSRT) (2004-12-06 14:45 UT --- 2004-12-07 00:58 UT) has detected a radio source with a mean flux density of 250 +/- 35 microJy at 5 GHz, with some possible evidence for fading during the run. The 5GHz WSRT source lies within one arcsec of the proposed optical counterpart (ATEL #354, ATEL #356).
The fading of the 15 GHz source combined with the positional coincidence of the 5GHz radio source with the proposed optical counterpart strongly suggests that this is the rapidly decaying radio counterpart of IGR J00291+5934. The origin of the radio emission is presumably the earlier transient production of a relativistic outflow.
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2004-12-07 23:18:00
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radio,optical,x-ray,pulsar,transient
|
362
|
BeppoSAX-WFC observations of IGR J11435-6109 and J00291+5934
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Jean in 't Zand & John Heise (SRON)
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The BeppoSAX Wide Field Cameras database entails 225 useful X-ray observations of the recently identified X-ray transient IGR J11435-6109 (ATel 350) obtained from July 1996 to April 2002. The net exposure time is 3.6 Msec. The data exhibit detections on 5 separate occasions: 21/22-jul-1996, 10/11-sep-1996, 11-apr-1997, 31-dec-2000/06-jan-2001 and 10-jan-2002. The highest flux on a time scale of one day is 7 mCrab (2-10 keV).
We analyzed in some detail the longest dataset (Dec 00/Jan 01), entailing 212 ksec of net exposure time. The source has a significance of 20. The position is R.A. = 11h44m00.4s, Decl. = -61d07'16" (J2000.0) with a 99%-confidence error circle radius of 1.4'. This is 2.0' from the 2.5'-accurate INTEGRAL position and 0.4' from the ROSAT source 1RXS J114358.1-610736. The spectrum can be described by an absorbed power law with NH=(9+/-2)E22 cm-2 and photon index 1.9+/-0.2. The average 2-10 keV flux is 1.3E-10 erg s-1 cm-2 (not corrected for absorption). Fourier analysis confirms the tentative pulsar detection by Swank & Markwardt (ATel 359). We find a pulse period of 161.76 +/- 0.01 sec. The pulse profile is broad with a 2-6 keV pulsed fraction of roughly 50%.
The outburst recurrence times are consistent with a 52.5 d orbital period as would be expected for a Be X-ray binary. However, the source was observed but not detected during ~10 intermediate outburst epochs.
We note that this source appears to have a long X-ray history. Einstein detected 2E 1141.6-6050 (at 0.4' from the ROSAT position) on Feb 5, 1980 (Thompson et al. 1996; AJ 115, 258).
Regarding the recently by Eckert et al. discovered accretion-powered ms pulsar IGR J00291+5934 (ATel 352; pulsar detection by Markwardt et al. ATel 353), the WFCs made 188 useful observations with a net exposure time of 2.9 Msec. The source was not detected, in persistent emission nor bursts. The detections reported by RXTE/ASM data by Remillard (ATel 357) were not covered by the WFCs. The first was covered 16 days after the last ASM detection and the second 11 days.
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2004-12-09 05:20:00
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x-ray,binary,neutron star,pulsar,star,transient
|
363
|
IGR J00291+5934 : IR counterpart detection and evidence of fading
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D. Steeghs, C. Blake, J. S. Bloom, M. A. P. Torres, P. G. Jonker (Harvard-Smithsonian Center for Astrophysics), D. Starr (Gemini, Hawaii)
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We report on the detection of IGR J00291+5934 (ATEL #352) at infrared wavelengths using the 1.3m robotic PAIRITEL telescope (http://pairitel.org) on Mt. Hopkins, AZ.
The IR counterpart for the accreting pulsar was detected on 2004 Dec 8 05:15 UT under cloudy conditions with PAIRITEL. Using nearby 2MASS comparison stars, we find preliminary magnitudes of J=16.8 +/- 0.1, H=16.8 +/- 0.3, K=16.1 +/- 0.2. Additional observations on Dec 9 01:35 and 03:20 UT suggest the source may have dropped in brightness in the IR between Dec 8 and Dec 9.
The source was also observed on 2004 Dec 9 02:46-03:02 UT with the FLWO 1.2m telescope on Mt. Hopkins as part of the CfA ToO program on X-ray Novae/transients. Using nearby GSC stars as reference, we find R=18.3 +/- 0.4 mag. The source appears to have faded significantly since the optical counterpart was announced on Dec 4 (ATEL #354), supporting the apparent decrease in brightness observed at IR wavelengths.
Weather permitting, we will continue to monitor the source at optical and IR wavelengths. Images are available at http://pairitel.org/IGRJ00291_5934
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2004-12-10 03:33:00
|
infra-red,optical,x-ray,binary,neutron star,nova,pulsar,star,transient
|
364
|
Further radio observations of IGR J00291+5934
|
M. P. Rupen (GSFC/NRAO), V. Dhawan, A. J. Mioduszewski (NRAO)
|
Very Large Array (VLA) observations of the millisecond pulsar IGR J00291+5934 (ATEL #352, ATEL #353) give a clear detection with a flux density of 0.17 +/- 0.05 mJy at 4.86 GHz on 9 December 2004 (MJD 53348.354). This flux density basically agrees with that measured by Fender et al. at nearly the same frequency on 6-7 December 2004 (ATel #361), suggesting that any decay is not very rapid. The VLA observation by itself was too short (about one hour) to usefully constrain the short timescale variability. Further observations are planned.
These data were taken in the VLA's most extended (A) configuration, yielding a restoring beam of 0.88 x 0.44 asec (FWHM), oriented 73 degrees east of north. A Gaussian+planar fit to the image gives an upper limit to the size of 0.53 arcsec FWHM, and a J2000 position within 0.2 arcseconds of the optical position given in ATel #354:
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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2004-12-10 04:00:00
|
radio,optical,x-ray,binary,neutron star,pulsar,star,transient
|
365
|
IGR J00291+5934 X-ray Decay Rate is Increasing
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J. H. Swank (NASA/GSFC) & C. B. Markwardt (U. Maryland & GSFC)
|
RXTE continues to monitor the millisecond X-ray pulsar IGR J00291+5934. The X-ray flux has decayed from a maximum of 29 mCrab (2-10 keV) on Dec 3, to less than 10 mCrab on Dec 11, 14:00 UTC.
Overall, the X-ray decay has been quite linear. However, within the past day, the rate of decline has increased slightly. If the decay continues on its present trend, it will become undetectable by the PCA within 2-3 days (i.e. by Dec ~14).
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2004-12-12 05:23:00
|
x-ray,binary,neutron star,pulsar,star,transient
|
366
|
Keck Optical Spectra of the Counterpart of IGR J00291+5934 Keck Optical Spectra of the Counterpart of IGR J00291+5934
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A. V. Filippenko, R. J. Foley (University of California, Berkeley), P. J. Callanan (Cork University)
|
Inspection of CCD spectra (range 320-940 nm) obtained on Dec. 12 UT with the Keck I 10-m telescope (+ LRIS; integration time 300 s on each of the blue and red sides) shows that the object detected by Fox & Kulkarni (ATEL #354) does indeed appear to be the optical counterpart to IGR J00291+5934 (ATEL #352), as was also noted by Roelofs et al. (ATEL #356). Superposed on the blue continuum are broad (FWHM = 1200 km/s) emission lines of H-alpha (equivalent width 0.96 nm), H-beta (EW = 0.54 nm), and He I 667.8 nm (EW = 0.1 nm), as well as narrow (FWHM = 300 km/s), very weak (EW = 0.06 nm) He II 468.6 nm emission.
|
2004-12-13 18:44:00
|
optical,binary,neutron star,pulsar,star,transient
|
367
|
Outburst from EXO 2030+375 detected with INTEGRAL
|
D. Gotz (IASF, Milano), J. A. Zurita Heras (ISDC, Geneva), C. Winkler (ESTEC), N. Gehrels (NASA/GSFC), S. Martinez-Nunez (Valencia), A. Bazzano (IASF, Roma), Alexander Lutovinov (IKI, Moscow)
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The HMXB pulsar EXO2030+375 was observed by INTEGRAL in a galactic plane scan on December 14, 2004 from 10:46:43 to 14:29:08 UTC. The 20-60 keV flux averaged on single pointings of 2200 sec increased from 93 to 214 mCrab. EXO 2030+375 was in the JEMX FOV during one pointing and was detected with average fluxes of 45 and 69 mCrab in the 3-10 kev and 10-31 keV bands. At 11:46:25 UTC the source did show a 450 s long outburst detected by the INTEGRAL Burst Alert System. Its pulse peak spectrum was characterized by a power-law with photon index 3.2+/-0.4 and a flux of 5E-9 erg/cm2/s in the 20-40 keV band corresponding to about 0.6 Crab. The 42 s characteristic pulsations are clearly detected. In the last pointing, the source was still brightening, reaching the highest level ever observed by INTEGRAL. INTEGRAL will reobserve the source on December 17.
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2004-12-15 20:09:00
|
x-ray,gamma ray,binary,neutron star,pulsar,star
|
368
|
Radio observations of Type Ic SN 2004gq
|
A. M. Soderberg (Caltech), S. R. Kulkarni (Caltech), D. A. Frail (NRAO)
|
We observed the optical position of the Type Ic SN 2004gq (IAUC # 8452 ) using the Very Large Array on 2004 Dec 16.20 UT. At 8.5 GHz we clearly detect the SN with a flux density of 2.0 +- 0.05 mJy. Assuming an explosion date between Dec 4.38 and 11.93 (based on optical photometry) places our radio measurement at t ~ 4.47 to 11.82 days. At a comparable epoch, SN 1998bw was 100 times more radio luminous than SN 2004gq. Further radio observations are planned.
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2004-12-17 03:00:00
|
radio,optical,gamma ray,gamma-ray burst,supernovae
|
369
|
IGR J00291+5934: an observation with Chandra
|
M. A. Nowak (MIT-CXC), A. Paizis (ISDC Geneva / IASF Milano), J. Wilms (Department of Physics, University of Warwick), K. Ebisawa (NASA - GSFC / ISDC Geneva), T. J.-L. Courvoisier (ISDC Geneva), J. Rodriguez (CEA Saclay / ISDC Geneva), R. Walter (ISDC Geneva), M. Del Santo (IASF Roma), P. Ubertini (IASF Roma)
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We have performed a preliminary analysis of a Chandra observation of IGR J00291+5934 that lasted 18 ksec, from 2004-12-14T02:43:41 to 2004-12-14T08:02:38 (UT time).
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2004-12-18 00:30:00
|
radio,infra-red,optical,x-ray,binary,neutron star,pulsar,star,transient
|
370
|
Optical counterpart to IGR J11435-6109
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José Miguel Torrejón, Ignacio Negueruela (Universidad de Alicante)
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Optical observations of the field of the 162-s pulsar IGR J11435-6109 (ATel #350, #359, #362) were conducted during the nights of December 14th and 15th with the 3.5-m NTT (La Silla) as backup for another programme.
As a likely identification of the INTEGRAL source with 1RXS J114358.1-610736 had been proposed (ATel #350), we first took a spectrum of the only star within the error circle of the ROSAT source (about 1" from the nominal position of the ROSAT source), USNO-B1.0 0288-0337417 (RA: 11h43m58.5s, Dec: -61d07'37"). The spectrum corresponds to an M star, with pronounced molecular bands. 1RXS J114358.1-610736 is hence associated with an active corona and is not the same source as IGR J11435-6109.
Moreover, slitless spectroscopy of the field reveals a moderately bright nearby object with H-alpha in emission. This is USNO-B1.0 0288-0337948 (RA: 11h44m10.7s, Dec: -61d07'02"), with magnitudes listed as b2=13.17, r2=12.95, i=11.61. The object lies within the BeppoSAX WFC error circle for IGR J11435-6109 (about 1.2' away from its nominal position) and also about 1.2' away from the Einstein position for 2E 1141.6-6050. It is 3' away from the centre of the INTEGRAL/IBIS error circle.
Long-slit spectroscopy of USNO-B1.0 0288-0337948 shows it to be a Be star of approximate spectral type B3. This is hence very likely the counterpart to IGR J11435-6109. The source would be a Be/X-ray transient, as suggested by the X-ray properties (ATel #362). Further analysis is in progress.
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2004-12-20 20:36:00
|
optical,x-ray,binary,pulsar,star,transient
|
371
|
Continued X-ray Brightening of V0332+53
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Ron Remillard (for ASM team at MIT and GSFC)
|
The XTE All-Sky monitor shows continued brightening of V0332+53, with an average flux of 1.1 Crab (2-12 keV) during the first half of 2004 Dec. 22. The true flux is certain to be substantially higher since the source is extremely hard, even for X-ray pulsars. The ASM count rate is evaluated here using cameras 2 and 3 only, since detector gain differences for camera 1 skew the results, given that normalizations are tied to the spectrum of the Crab Nebula. V0332+53 is the brightest X-ray pulsar observed with the ASM since the outburst maximum of the 'bursting pulsar' (GRO J1744-28), which was observed at 1.3 Crab on 1996 January 12. The average hardness ratio (5-12 keV / 3-5 keV) for V0332+53 over the last 18 days is HR2 = 3.40, which exceeds other pulsars, e.g. GRO J1744-28 (2.4), Vela X-1 (2.4), Cen X-3 (2.1), and 4U0115+63 (3.0).
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2004-12-22 23:21:00
|
x-ray,pulsar,transient
|
372
|
INTEGRAL hard X-ray observation of V0332+53
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M. Turler (ISDC, Geneva Observatory), G. Di Cocco (IASF/CNR, Bologna), R. Diehl (MPE, Garching), S. Maisala (University of Helsinki), M. Mas-Hesse (LAEFF, Madrid), N. Mowlavi (ISDC, Geneva Observatory), A. Orr (ESTEC, Noordwijk), J. Paul (CEN, Saclay), R. A. Sunyaev (IKI, Moscow & MPA, Garching)
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The steadily brightening pulsar V0332+53 (Remillard et al. 2004 ATEL #371) was in the INTEGRAL field of view (FoV) for 2.2 ksec during a routine Galactic Plane Scan observation starting on Dec. 26, 2004 at 12:48:30 UT. The source was located at the border of the IBIS FoV (13.4 deg from the center) and thus could not be seen by the JEM-X instrument. The IBIS/ISGRI spectral analysis as compared to a recent Crab observation in a similar off-axis position gives fluxes of 1.0, 0.33 and 0.05 Crab in the 21-36, 36-58 and 60-200 keV bands, respectively. The uncertainties can reach 30% due to the fact that the source is at the border of the FoV. Together with the RXTE ASM observations reported by Remillard et al. (2004 ATEL #371) this suggests a flux maximum in Crab units at an energy around 10-20 keV.
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2004-12-29 00:55:00
|
x-ray,gamma ray,binary,neutron star,pulsar,star,transient
|
373
|
RADIO DETECTION OF SGR 1806-20 FOLLOWING A GIANT FLARE
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B. M. Gaensler (CfA), C. Kouveliotou (NASA/MSFC, NSSTC), R. Wijers (University of Amsterdam), M. Garrett (JIVE), M. Finger, P. Woods, S. Patel (USRA, NSSTC), M. McLaughlin (Jodrell Bank) report on behalf of a larger team:
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We observed the soft gamma-ray repeater SGR 1806-20 with the Very Large Array, approximately 7 days after the detection of a Giant Flare from the source (Borkowski, J. et al., 2004, GCN # 2920), on January 3, 2005 for one hour (19:46-20:46 UT). At frequencies of 1.4, 4.9 and 8.5 GHz, we detect an unresolved radio source at coordinates (J2000) RA 18h08m39.3s, Dec -20o24'39.7", with an approximate uncertainty of 0.1" in each coordinate. This is consistent with the X-ray position of SGR 1806-20 as given by Kaplan et al., ApJ 564, 935 (2002). Since this is the first time the source has been observed in radio, we suggest that we detected transient emission from a synchrotron wind bubble, as was seen by Frail et al., Nature, 398, 127 (1999) one to two weeks after a Giant Flare from SGR 1900+14. The preliminary flux density of the source is 160 +/-10, 78 +/-3 and 45 +/-3, mJy at 1.4, 4.9 and 8.5 GHz, respectively. Further observations are planned with the VLA on January 4, 14:15-15:15 UT. We are grateful to the VLA Scheduling Officers (Jim Ulvestadt and Joan Wrobel) for approving our request for Target of Opportunity observations of the source.
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2005-01-04 04:36:00
|
radio,x-ray,gamma ray,neutron star,pulsar,soft gamma-ray repeater,star,transient,variables
|
374
|
M101 ULX-1 Brightens
|
GSFC & LHEA
|
A series of four Chandra observations since 22 December 2004 show that M101 ULX-1 (CXO KM101 J140332.74+542102, the subject of Atels #222, 305, 306, and 311) has brightened significantly.
The count-rate of the first two observations is too low to allow spectral fitting. The spectrum from the 30 Dec 2004 observation provided about 620 counts, allowing a reasonable spectral fit. There is no significant flux above 1 keV, and the spectrum is well fit by an absorbed black-body spectrum (NH=3.5e21, kT=0.06+/-0.01). The peak of the emission is 0.5 keV. The spectrum from the 01 Jan 2005 observation provided about 1250 counts, again allowing spectral fitting. There is significant flux above 1 keV, and the peak of the emission is around 0.7 keV. It is also reasonably well fit by an absorbed black-body spectrum (NH=6.5e20, kT=0.166+/-0.02). There is clearly strong spectral evolution from 30 December to 1 January. The luminosities in the table below are the absorbed luminosities. For the last two observations, the luminosities are calculated from the model fits. For the first two, we have used the model of the 30 December observation scaled by the 0.3-2.5 keV count rate.
This object also brightened significantly in 05-11 July 2004, but had returned to its quiescent level by 23 July 2004. In that episode, the spectrum looked very similar to the 30 December 2004 spectrum, and although there are some signs that the spectrum did change over the course of the observations, it never acquired the hard tail seen in our 1 January 2005 observation. A hard tail has been observed in this object; the initial 26-27 March 2000 observation by Chandra, when the absorbed 0.5-2.0 keV luminosity was about 1.0e39 ergs/s(Pence et al,2001 ApJ 561, 189, Mukai et al, 2003, ApJ 582, 184). As on that occasion, the 0.5-2.0 keV flux is strongly and rapidly variable.
Optical spectra between 3500 and 5900 Angstroms of this object were obtained on 24 July 2004 with the Gemini telescope, one day after an XMM observation showed that the object had returned to its quiescent level. The spectrum showed some continuum, as well as strong HeII (4686) and HeI (5876), confirming the optical counterpart found by Kuntz et al (submitted). Further optical observations of this object, particularly when it is in outburst, are important for understanding the physical nature of this object.
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2005-01-04 09:16:00
|
optical,x-ray,binary,transient,variables
|
375
|
Second-epoch VLA observations of SGR 1806-20
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B. M. Gaensler (CfA), C. Kouveliotou (NASA/MSFC, NSSTC), R. Wijers (U. Amsterdam), M. Garrett (JIVE), M. Finger, P. Woods, S. Patel (USRA, NSSTC), M. McLaughlin (Jodrell Bank), R. Fender (U. Southampton), T. Delaney (CfA) report on behalf of a larger team:
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We observed the soft gamma-ray repeater SGR 1806-20 with the Very Large Array (VLA) in the A-configuration for a second time on January 4, 2005 for one hour (14:15-15:15 UT). We detect the source at the same coordinates as reported by Gaensler et al. (GCN #2929; ATEL #373). Preliminary flux levels, including improved estimates of the fluxes reported in ATEL #373, are as follows (the numbers in parentheses indicate approximate uncertainties in the last significant figures):
A reanalysis of the VLA data from 3 Jan 2004 (GCN #2928, GCN #2929; ATEL #373) suggests that the radio source associated with SGR 1806-20 is slightly extended at both 4.9 and 8.5 GHz. Assuming that the underlying geometry is an optically thin, spherical thin shell, data at both frequencies independently suggest a source of approximate diameter 50-100 milliarcseconds. This implies a projected expansion speed of approx (0.3-0.6)c over the 7 days since the initial giant SGR flare (assuming a source distance of 15.1 kpc; Eikenberry, S. et al., ApJ 616, 506, 2004).
Further radio observations of this source with the Westerbork Synthesis Radio Telescope (WSRT), the MERLIN VLBI network and the Parkes Radio Observatory are currently underway or are being scheduled, and will be reported as they are analyzed. We will continue monitoring the source with the VLA until it fades below detection level.
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2005-01-04 23:31:00
|
radio,gamma ray,neutron star,pulsar,soft gamma-ray repeater,star,transient,variables
|
376
|
Radio observations of SNLS-04D2jz
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Avishay Gal-Yam (Caltech)
|
A. Gal-Yam, A. Soderberg and M. Sullivan report for a larger collaboration: We have observed with the Very Large Array (VLA) the location of supernova SNLS-04D2jz, discovered on November 21, 2004 by the Supernova Legacy Survey (SNLS), using Megacam mounted on the 3.6m CFHT telescope. Spectroscopy obtained by R. Ellis and M. Sullivan using the Keck I 10m telescope (+LRIS) shows this event is of type Ib/c, spectroscopically similar to SN 1998bw (associated with GRB 980425), at a redshift of z=0.323. Analysis of our radio data (1hr integration at 8.5 GHz) does not yield a detection of the SN. The flux measured at the optical position is 31 +/- 26 uJy at 8.5 GHz. Correcting for the luminosity distance (assuming standard concordance cosmology) we find that this event may have been as radio luminous as local type Ib/c SNe (including SN 1998bw) but does not have a radio afterglow signature expected from long-duration GRBs at comparable redshifts, which would have been easily detected by our VLA observations.
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2005-01-05 05:58:00
|
radio,optical,gamma ray,gamma-ray burst,supernovae
|
377
|
The Orbital Period of IGR J11435-6109
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R. H.D. Corbet (NASA/GSFC and USRA) and R. Remillard (MIT)
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The power spectrum of the Rossi X-ray Timing Explorer All Sky Monitor light curve of IGR J11435-6109 (ATEL #350, #358, #359, #362) obtained between 1996 January 5 and 2004 December 30 shows significant modulation at a period of 52.5 days. This confirms the orbital period proposed by in 't Zand & Heise (2004, ATEL #362). The mean flux measured with the ASM during this interval is 0.19 +/- 0.01 counts/s (2 - 12 keV), equivalent to 2.7 mCrab, and the Fourier amplitude of the modulation is 0.09 +/- 0.01 counts/s. A sine wave fit to the ASM light curve gives parameters of: period = 52.46 +/- 0.06 days and epoch of maximum flux = MJD 53069.5 +/- 1.9
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2005-01-06 00:43:00
|
x-ray,binary,neutron star,pulsar,star,transient
|
378
|
Possible identification of the IR counterpart of SGR 1806-20
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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 recent radio detection of SGR 1806-20 (Gaensler et al. 2005, GCN 2929) which provided an unprecedented positional accuracy (at the level of 0.1"), we re-analysed all the VLT NACO images of the field (in J, H and Ks bands) we collected in 2004 after the X-ray burst activity from the source detected during March, June, August and October 2004 (Mereghetti et al. 2004, GCN 2541, Golenetskii et al. 2004, GCN 2693 and 2823).
We have detected several sources (Israel et al. 2004, GCN 2609) within the Chandra error circle (radius of 0.3") reported in Eikenberry et al. 2001 (ApJ 563, L133) and Kaplan et al. 2002 (ApJ, 564, 935). However, only one faint object (Ks=21.6+\-1.0) is consistent with the VLA radio position (Kouveliotou et al. 2005, GCN 2929) and within the Chandra error circle. The source was detected in the June and September 2004 images, during which the sky conditions were exceptionally good (on-axis PSF of about 0.09") and with a long exposure time (about 6000s in the Ks band; Ks limiting magnitude of about 23). No flux variability has been detected from the source within the relatively large magnitude uncertainties. Candidate C, proposed by Eikenberry et al. 2001, is about 0.5" away form the radio position and resolved in at least 2 point-like objects within the VLT NACO images.
This message can be cited.
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2005-01-06 02:27:00
|
radio,infra-red,x-ray,gamma ray,soft gamma-ray repeater
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379
|
M31 optical transient
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R. Quimby, P. Mondol, and F. Castro (University of Texas)
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We report the detection of an optical transient in M31 using ROTSE-IIIb at the McDonald observatory, Texas. The transient is located at 00h42m28.17s +41o09'55".5. We note this is about 5" from the Chandra X-ray point source CXOM31 J004228.1+410959 (Kong et al. 2002, ApJ 577,738). Unfiltered images taken on Dec. 26.06 UT show it was 16.4 mag; on Dec. 28.07 it was 16.2 mag and on Dec. 31.08 it was 16.9 mag. ROTSE-IIIb images taken on Dec. 15.06 show nothing at this location to 17.8 mag.
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2005-01-06 04:03:00
|
optical,x-ray,nova,transient
|
380
|
Fourth Epoch observations of SGR 1806-20
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P. B. Cameron (Caltech) and S. R. Kulkarni (Caltech)
|
We observed a fourth epoch of the position of SGR 1806-20 with the Very Large Array (VLA) in A-configuration on 2005 Jan 6.77 UT (t ~ 9.9 days after the giant flare. See GCN #2920, #2928, #2929, #2933, #2934, #2935, ATEL #373, #375). We find the following preliminary flux densities: Freq. Â Â Â Flux Density (GHz) Â Â (mJy) =========================== 1.46 Â Â Â 96 +/- 2 4.86 Â Â Â 39 +/- 2 8.46 Â Â Â 24 +/- 1 =========================== Error Bars are 1 sigma. We find an angular size at 8.46 GHz of about 80 mas. We see no variation in this diameter over the last 4 days. The National Radio Astronomy Observatory is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation.
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2005-01-07 05:29:00
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radio,gamma ray,neutron star,pulsar,soft gamma-ray repeater,star,transient,variables
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381
|
Multiple Cyclotron Lines in V0332+53
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W. Coburn (SSL/UCB), P. Kretschmar (MPE/ISDC), I. Kreykenbohm (IAAT/ISDC), V. A. McBride (Southampton University), R. E. Rothschild (CASS/UCSD), J. Wilms (Warwick)
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As part of our continuing RXTE observing campaign of V0332+53 in outburst (ATEL #372, #371, #349), we obtained 63ks of good exposure time between 2004 December 24-26. We measured a 2-10keV flux of 2.6E-8 ergs/cm2/s with the PCA. In our RXTE spectrum, once a standard pulsar continua is fit there are clear, line-like residuals at ~25 and ~50keV. This is not surprising since Makishima et al. (1990, ApJ 356 59L) first reported a 28.5keV cyclotron line in the source using observations obtained with Ginga. Fitting with Gaussian-shaped absorption lines, we find a pair of features with energies (26.34+/-0.03)keV and (49.1+/-0.2)keV. However, the fundamental is poorly fit with a simple Gaussian, or even pair of Gaussian, and there is evidence in the residuals for considerable non-Gaussian shaped structure at that energy. Since this residual structure was dominating the fits, we looked at the HEXTE-only spectra above 35keV and found another line-like feature at (74+/2)keV. This makes V0332+53 the only accreting pulsar other than 4U0115+63 to exhibit more than two cyclotron lines.
|
2005-01-07 05:37:00
|
x-ray,gamma ray,binary,neutron star,pulsar,star,transient
|
382
|
Public data available on INTEGRAL TOO observations of V0332+053 in outburst
|
S. Soldi, N. Produit (ISDC, Geneva), G. Belanger (CEA Saclay), S. Larsson (Stockholm observatory), G. Palumbo (Bologna University), A. Santangelo (Tubingen University), O. R. Williams (ISOC), C. Winkler (ESTEC, Noordwijk)
|
INTEGRAL performed a TOO observation of the outburst of the pulsar V0332+53 (ATEL #381, #372, #371, #349) from 2005 January 6 to 10. About 110 ksec of good data were obtained. During the observation, the source was still very bright with a mean flux of ~650 mCrab in the 20-60 keV band. The multi-instrument spectrum of very high signal to noise confirms the presence of three cyclotron lines at energies of ~25, ~55 and ~75 keV, and of a complex continuum. The near real time data of that TOO observation will become immediately public. Quick-look analysis results and a set of tar files containing preliminary data (and auxiliary files) are available at http://isdc.unige.ch/?Science+news As part of the observation was affected by operational problems the consolidated data from that observation will be available through the ISDC archive in about two months.
|
2005-01-12 19:52:00
|
x-ray,gamma ray,pulsar,transient
|
383
|
Optical Outburst of the Halo Black Hole X-ray Transient XTE J1118+480
|
C. Zurita (IAC), D. RodrÃguez (M-1 group), P. RodrÃguez-Gil (IAC), J. Casares (IAC), T. Shahbaz (IAC), J. Acosta (IAC), G. Gómez-Velarde (IAC), C. Abajas (IAC), T. Muñoz-Darias (IAC)
|
We report the discovery of a new outburst of the black hole X-ray transient XTE J1118+480 (IAUC # 7418 , ATEL#64, #67). Observations carried out with the 0.8m IAC80 telescope at the Observatorio del Teide on UT 2005 Jan 9.26 show J1118+480(=KV UMa) at R=14.02, almost 5 mag brighter than the reported quiescent level (IAUC # 7868 ). On UT Jan 12.12-12.30 J1118+480 brightened to R=13.41 (V-R=0.19) with significant variability of ~0.05 mag amplitude. Observations at all wavelengths urged.
|
2005-01-13 06:03:00
|
optical,x-ray,binary,black hole,transient,request for observations
|
384
|
Faint X-ray Outburst in XTE J1118+480
|
R. Remillard (MIT), M. Garcia, M. A. P. Torres, D. Steeghs (SAO), and the ASM team at MIT and GSFC
|
The RXTE All-Sky monitor shows new detections of the black hole binary, XTE J1118+480, reported to be in optical outburst (ATEL #383). The source is first seen on 2005 January 9, with an average flux of 15(4) mCrab at 2-12 keV. The flux increases only slightly to 16(3) mCrab on Jan. 10, and to 19(3) mCrab on Jan. 11. The X-ray hardness ratios suggest that the source is in the hard state, as was the case for the entire outburst of 2000 January-July.
|
2005-01-13 06:42:00
|
optical,x-ray,binary,black hole,transient
|
385
|
Radio detection of XTE J1118+480 at 15 GHz
|
G. G.Pooley
|
A renewed optical and X-ray outburst of the Black Hole candidate XTE J1118+480 is reported in ATEL#383 and ATEL#384. A radio observation at 15 GHz was made with the Ryle Telescope at Cambridge from 2005 Jan 12 21h59m to Jan 13 09h57m (UT). The mean flux density was 8.7 mJy, with an increase of about 10% during the 12-h observation. This flux density is close to the mean (9.0 mJy) found during observations of the previous outburst in 2000 Mar - Jun.
|
2005-01-13 18:32:00
|
radio,optical,x-ray,black hole,transient,request for observations
|
386
|
Optical Outburst of XTE J1118+480
|
U. Kiziloglu (METU), S. Balman (METU), A. Baykal (METU), E. Gogus (SU), A. Alpar (SU), C. Inam (Baskent)
|
We report the monitoring of black hole X-ray transient XTE J1118+480(=KV UMa) during its new optical outburst and faint X-ray outburst. The data is obtained with the ROTSE IIId telescope (Robotic Optical Transient Search Experiment III) at TUG (Tubitak National Observatory) Antalya, Turkey (IAUC# 7418 , ATEL#64, #67, #383, #384, #385). The observations stared on UT 2004 Dec 12.9 and the source is still being monitored by our group. XTE J1118+480 was found in quiescence (using ROTSE calibrated [USNO A2.0] R magnitudes) on 2005 Jan 4.95 at a magnitude of R=17.7 . Following this date, on 2005 Jan 6.94 R=14.3, and on 2005 Jan 9.94 R=13.3. Our final observation on 2005 Jan 12.93 indicates R=12.93 for the source. The lightcurve is tending to a plateau (probable maximum). The rise in the light curve can not be fitted with a single power law or exponential function. We find that the rise can be modelled using a power law with an index of ~ 0.14 followed by an exponentail rise with a time constant of ~1.55 days. A light curve of the optical outburst of XTE J1118+480 can be found at the URL http://astroa.physics.metu.edu.tr/BHC along with images in quiesence and outburst.
|
2005-01-14 01:34:00
|
optical,x-ray,binary,black hole,transient,request for observations
|
387
|
Further radio observations of XTE J1118+480
|
M. P. Rupen (NRAO/GSFC), V. Dhawan, A. J. Mioduszewski (NRAO)
|
Very Large Array (VLA) observations of the black hole candidate binary XTE J1118+480 (e.g., ATEL #383, ATEL #384, ATEL #386) confirm Pooley's report of renewed radio activity (ATEL #385). All data were observed on MJD 53383.32-.35, overlapping the end of Pooley's observations. A preliminary reduction gives the following spectrum:
The uncertainties are 1sigma based on the rms noise in the map. The overall spectrum is roughly flat above 8 GHz, consistent with Pooley's 15 GHz datum, and as expected for a source in the low/hard state. The sharply rising spectrum from 4.9 to 8.5 GHz (nu^0.89+/-0.04) is more surprising, and may suggest an additional source of absorption, e.g., from ionized gas near the source. 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.
|
2005-01-14 05:50:00
|
radio,optical,x-ray,binary,black hole,transient
|
388
|
Optical observations of BQ Cam (=V0332+53) in outburst
|
Nicola Masetti, Mauro Orlandini (INAF - IASF, Bologna), Silvia Marinoni (INAF - Oss. Astron. Bologna) and Andrea Santangelo (Universitaet Tuebingen)
|
We have observed BQ Cam, the optical counterpart of the X-ray binary source V0332+53, which is now undergoing an outburst (see ATel #349, #371). Optical Spectroscopy and V-band photometry were acquired on January 7, 2005, between the two INTEGRAL pointings described in ATel #382, with the "G.D. Cassini" 152 cm Loiano telescope (plus BFOSC and EEV CCD) of the Observatory of Bologna. Observations were carried out between 22:48 and 23:41 UT under a seeing of about 2 arcsec.
The object is at V ~ 15.2 and its spectrum shows a reddened blue continuum over which a prominent, single-peaked Halpha emission line with equivalent width (EW) around 10 Angstroms is detected. HeI emissions at 5875, 6678 and 7065 Angstroms are also detected. These V-band magnitude and Halpha EW values are typically shown by BQ Cam during outbursts (see e.g. Iye & Kodaira, 1985, PASP, 97, 1186; Goranskij, 2001, Astron. Lett. 27, 516; Goranskij & Barsukova, 2004, ATel #245).
We acknowledge the Astronomical Observatory of Bologna for the Service Programme in Loiano.
|
2005-01-15 00:46:00
|
optical,x-ray,binary,neutron star,star,transient
|
389
|
Optical Variability in XTE J1118+480
|
R. I. Hynes (Louisiana State University), T. K. Watson (Southwestern University), D. E. Winget, E. L. Robinson (University of Texas at Austin)
|
High time-resolution (1-sec) white light photometry of the outbursting black hole XTE J1118+480 (ATEL #383, #384, #385, #386, #387) was obtained with the Argos CCD photometer on the McDonald Observatory 2.1m telescope on 2005 January 13.35. Significant optical variability was detected on timescales shorter than 100s, with an rms amplitude of 3% integrated from 0.01-0.5Hz. As in the previous outburst, the power spectral density takes the form of band-limited noise, but with a higher break frequency at 0.12Hz. No quasi-periodic oscillation was detected. Further monitoring at the highest possible time-resolution (a few sec or better) is encouraged.
|
2005-01-15 01:20:00
|
optical,binary,black hole,transient
|
390
|
RXTE PCA Observations of XTE J1118+480
|
Jean Swank (GSFC), Craig Markwardt (GSFC/UMD)
|
RXTE had pointed observations of XTE J1118+480 for 660 and 960 seconds, respectively, on Jan. 13, 2005 at 6:31 UT and Jan 14, 3:17 UT. The average spectra were well fit with a power law of photon index 1.8 and an iron line with 42 eV equivalent width. The fluxes were equivalent to 20 and 21 mCrab 2-10 keV. With as much flux again above 10 keV, the X-ray luminosity above 2.5 keV is 3.7E35 ergs/s. The power density spectra indicate variability below 0.1 Hz of 25-30%, with possible quasiperiodic oscillations near 0.02 Hz. These observations, in which the spectrum is very similar to that observed in 2000, are much earlier in the outburst. Further observations are planned.
|
2005-01-15 07:50:00
|
x-ray,binary,black hole,transient
|
391
|
Type determination for SN 2004gw and SN 2005D
|
Avishay Gal-Yam (Caltech)
|
Avishay Gal-Yam reports for the Caltech Core-Collapse Program (CCCP): We have observed the unidentified supernovae SN 1994gw (Puckett & Ireland et al., IAUC # 8459 ), and SN 2005D (Burket & Li, IAUC # 8464 ) with the DBSP spectrograph mounted on the 200" Hale Telescope at Palomar observatory. Preliminary analysis shows that SN 1994gw is of type I. Numerous features redward of 600 nm, as well as the overall red continuum, suggest it is a type Ic, but final reduction of the spectra is required for a secure ID. SN 2005D is a type II SN, showing broad Halpha and Hbeta lines.
|
2005-01-16 09:26:00
|
optical,supernovae
|
392
|
Spectroscopic identification of supernovae
|
Avishay Gal-Yam (Caltech)
|
Avishay Gal-Yam reports the following spectroscopic observations of supernovae by the CCCP, all obtained with the DBSP spectrograph mounted on the 200" Hale telescope at Palomar Observatory: A spectrum of SN 2005E (Graham & Li, IAUC # 8465 ) indicates a type Ib, consistent with the identification by Foley & Filippenko (same IAUC). A spectrum of SN 2004gz (Puckett & Cox, IAUC # 8460 ) indicates it is probably of type Ia, a few weeks after maximum light. A spectrum of SN 2005B (Lane, Gray & Boles, IAUC # 8462 ) indicates it is a young type II SN, with blue continuum and lines of Halpha and Hbeta. A spectrum of the SN candidate in IC983 circulated by Li confirms it is indeed a SN of type II, with red continuum and well evolved lines of Halpha and IR Ca triplet, suggesting it is probably quite old. Finally, we wish to clarify that the observations reported in our previous telegram (ATEL #391) were of SN 2004gw, and not SN 1994gw, and thank H. Yamaoka for alerting us to our error.
|
2005-01-16 21:36:00
|
optical,supernovae
|
393
|
Infrared Observations of XTE J1118+480
|
R. I. Hynes (Louisiana State Univ.), D. M. Gelino (Caltech), K. J. Pearson (Louisiana State Univ.), E. L. Robinson (Univ. of Texas)
|
Infrared observations of the outbursting black hole XTE J1118+480 (ATEL #383) were performed using SQIID on the Kitt Peak National Observatory 2.1m telescope. Observations spanning 2005 January 15.42-15.58 found it somewhat fainter than the previous outburst (IAUC # 7394 , # 7407 ), at average brightness J=12.91+/-0.03, H=12.50+/-0.03, K=11.95+/-0.03. The colors again correspond to an approximately flat spectrum in F_nu. No orbital variation is apparent, but there is substantial unresolved rapid variability with rms amplitude 22% in K (between 2s exposures). Further observations are planned nightly until Jan 21.
|
2005-01-17 22:24:00
|
infra-red,binary,black hole,transient
|
394
|
IGR J00234+6141: A new weak hard X-ray source found by INTEGRAL
|
P. R. den Hartog (1), L. Kuiper (1), W. Hermsen (1, 2), J. Vink(1), J. J.M. in 't Zand (1, 3), R. H.D. Corbet (4), R. Remillard (5) (1 SRON Utrecht; 2 University of Amsterdam; 3 University of Utrecht; 4 NASA/GSFC and USRA; 5 MIT)
|
We report the discovery by INTEGRAL of a new hard X-ray source, IGR J00234+6141. This source was detected accumulating data from different observations in December 2003 and February 2004 resulting in a 1.6-Ms exposure targeting the Cassiopeia region. The source is weak with a flux of 1.20 +/- 0.15 mCrab and a detection significance of 8 sigma in the energy band 20-30 keV of IBIS/ISGRI. Also in the 30-40 keV band the source is seen, at a 3.8-sigma level with flux 0.8 +/- 0.2 mCrab. Corresponding photon fluxes are (1.35 +/- 0.17)E-5 ph/cm2/s/keV and (4.25 +/- 1.13)E-6 ph/cm2/s/keV. The source is too weak to perform variability studies using the presently available INTEGRAL data.
The best source postion is R.A. = 0h 23m 24s, Decl. = +61o 41' 32" (J2000) with an estimated 3' accuracy (90% confidence level). The position of the ROSAT X-ray source 1RXS J002258.3+614111, which is located 3.15' from the INTEGRAL centroid, is marginally consistent with the INTEGRAL position. A newly derived RXTE-ASM light curve shows a marginal detection of the source, and no modulation was found.
Given its position close to the Galactic plane (b = -1 deg.), the lack of a radio counterpart and the nature of the majority of previously reported new INTEGRAL sources, it is likely to be an X-ray binary, rather than a source with an extragalactic origin.
|
2005-01-19 17:45:00
|
radio,x-ray,gamma ray,binary,neutron star,star
|
395
|
Optical monitoring of IGR J00291+5934
|
I. Bikmaev, V. Suleimanov, A. Galeev, N. Sakhibullin (KSU/AST), A. Alpar (SU), Z. Aslan, I. Khamitov (TUG), R. Burenin, M. Pavlinsky (IKI), R. Sunyaev (MPA/IKI)
|
We have photometrically monitored the optical transient associated with the accretion-powered millisecond pulsar IGRJ00291+5934 (ATEL352,353,354,363) during the period of December 11, 2004 - January 13, 2005, with Russian-Turkish 1.5-m optical telescope (RTT150) at Bakirlitepe (Antalya, Turkey). The R-band light curve is shown at http://db.rsdc.rssi.ru/IGRJ00291+5934/fig1.jpg Optical flux decay is nearly exponential with e-folding time 5.66+/-0.2 days. The rate of optical flux decay is consistent with the decay rate in 2.5-25 keV X-Ray flux during the first 10-15 days after the burst (Galloway et al.,2005, astro-ph/0501064). Optical brightness variations with amplitude ~ 0.3 mag at timescales of hours were detected when the transient was bright enough (R~19-21 mag). A possible re-brightening of the optical transient was detected ~ 40 days after the burst (January 9-13, 2005). We note, that after the optical transient of SAX J1808.4-3658 (Giles et al., MNRAS, 1999,304,47, R.Wijnands, astro-ph/0501264), this is the second accretion powered millisecond pulsar with an observed decay in the optical.
|
2005-01-25 00:03:00
|
optical,x-ray,binary,neutron star,pulsar,star,transient
|
396
|
Type determination for SN 2004M
|
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)
|
We report that a spectrum (range 330-990 nm) of SN 2005M (IAUC # 8470 ), obtained Jan 24.52 UT with the SuperNova Integral Field Spectrograph on the University of Hawaii 2.2m telescope, shows it to be a type Ia SN most similar to SN 1991T about 12 days before maximum. Weak Ca II H&K and Fe III features are evident. The spectrum is very blue, and lacks interstellar Na I D, indicating very little or no extinction.
|
2005-01-26 08:33:00
|
optical,supernovae
|
397
|
Correction to ATEL #396: Type determination for SN 2005M
|
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)
|
The title of ATEL #396 should read "Type determination for SN 2005M"
|
2005-01-26 08:38:00
|
optical,supernovae
|
398
|
Comet 69P/Taylor observed by LOSS/KAIT
|
University of California, Berkeley
|
W. Li, University of California at Berkeley, reports that Comet 69P/Taylor was serendipitously imaged by LOSS/KAIT [see Filippenko et al. 2001, in "Small-Telescope Astronomy on Global Scales," ed. W. P. Chen et al. (San Francisco: ASP), p. 121] on Jan 22.3322 UT in the field of the galaxy MCG +05-22-004. The position of the comet is measured as R.A. = 9h4m9s.67, Decl. = +29 45'28".9 (J2000.0; uncertainty 0".3 on both axes). The comet has an unfiltered mag of roughly 17, and has a tail about 15" in size with position angle about 120 degrees.
|
2005-01-26 08:58:00
|
optical,comet
|
399
|
Periodic Humps in XTE J1118+480 2005 Outburst
|
Y. Chou (National Central University), A. Chen (National Cheng Kung University), P. S. Chiang (National Cheng Kung University), A. C. Chen (National Central University), Z. Y. Lin (National Central University), Y. Chung (National Central University)
|
We report the follow-up observations of the outbursting black hole X-ray transient XTE J1118+480 (KV UMa, ATEL #383, #384, #385, #386, #387, #389, #393) made by Lulin One-meter Telescope (LOT), Taiwan. The observations were started on UT 2005 Jan 16.74 and the source is still monitoring. The brightness of the source is now declining with a rate of ~0.04 mag/d. The mean V band magnitudes detected each night by LOT were: Jan 16.814, 13.47; 17.784, 13.52; 18.758, 13.56; 19.781, 13.58; 20.779, 13.61; 21.792, 13.65; 22.882, 13.71 and 23.863, 13.82. A preliminary timing analysis shows that weak (amp ~0.02 mag) but significant periodic humps with a period of ~4 hrs, close to the one discovered in previous outburst (IAUC# 7418) , can be detected on the light curves between Jan 18.6 and 20.9. The false alarm probability of this signal obtained by Analysis of Variance (AoV) is less than 1e-5. The periodic humps may be owing to the orbital variations or the superhumps. More observations are planned for further investigations.
|
2005-01-26 15:30:00
|
optical,x-ray,binary,black hole,transient,variables
|
400
|
4.85 and 10.45 GHz observations of XTE J1118+480 following the VLA measurements
|
Emmanouil Angelakis, Alexander Kraus (Max Planck Instuitute for Radio Astronomy, Bonn)
|
Observations of the black hole candidate binary XTE J1118+480 have been carried out with the 100-m Radio Telescope at Effelsberg (Max Planck Institute for Radio Astronomy).
The observations took place during 2 time slots separated by roughly one day (between JD 2453384.47 and 2453385.41) starting approximately 1 day after the VLA observations. The first set has been carried out under unstable weather conditions whereas the second part under considerably good ones. Â
The source has been observed repeatedly at both frequencies. The weighted measured values are as follows:
XTE J1118+480 was also targeted with the 32 GHz receiver but unfortunately the bad weather prevented us from carrying out reliable measurements at this frequency. Nevertheless, weather permitted, future observations at these band will be attempted.
|
2005-01-27 06:00:00
|
radio,binary,black hole,transient
|
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