| --- |
| license: cc-by-4.0 |
| task_categories: |
| - image-to-image |
| tags: |
| - astronomy |
| - supernovae |
| - panstarrs |
| - delight |
| size_categories: |
| - 10K<n<100K |
| --- |
| |
| ## Description |
|
|
| This is the dataset from DELIGHT [1], a model that locates the host galaxy of a |
| transient from multi-resolution images. The difference with the original is that |
| the images are **not** the cutouts used in the paper: they were regenerated from |
| [hips2fits](https://alasky.cds.unistra.fr/hips-image-services/hips2fits) |
| (PanSTARRS DR1 HiPS, served by CDS). |
|
|
| It contains **12,610 examples**, built by **autolabeling**: transient positions are |
| **simulated**, not observed. For each of the 7,093 host galaxies in |
| [h2f_delight_train](https://huggingface.co/datasets/PRISM-Astro/h2f_delight_train), |
| positions are drawn **uniformly** inside the elliptical footprint of its r-band |
| Sérsic fit, truncated at 3·Re. |
|
|
| This is exactly how |
| [h2f_delight_autolabeling_1pct](https://huggingface.co/datasets/PRISM-Astro/h2f_delight_autolabeling_1pct) |
| was built. **The only difference is how many positions each galaxy gets**, and |
| that is what the `radius_norm` name refers to. |
|
|
| This variant uses the exponent `p = 4`. Its sibling |
| [h2f_delight_radius_norm](https://huggingface.co/datasets/PRISM-Astro/h2f_delight_radius_norm) |
| uses `p = 6`; see the comparison at the end. |
|
|
| ## How many examples per galaxy: `radius_norm` |
| |
| ### The problem |
| |
| A galaxy can only place a transient as far as **3·Re** from its own center. A |
| small galaxy simply cannot produce a large transient–host distance. |
| |
| Most galaxies are small. So if every galaxy contributes roughly the same number |
| of examples, nearly all of them land at short distances and the long ones are |
| almost missing. In `1pct`, the fullest distance bin holds **338 times** more |
| examples than the emptiest one. |
| |
| ### The rule |
| |
| Bigger galaxies generate more examples: |
| |
| ``` |
| n = max(1, round((Re / Re0) ** p)) Re0 = 8 arcsec, p = 4 |
| ``` |
| |
| `Re0` is the size at which a galaxy starts generating more than one example. |
| Below it, a galaxy contributes exactly one. **No galaxy is ever dropped**: all |
| 7,093 are present, and 90.6 % of them contribute a single example. Only 667 |
| galaxies (9.4 %) contribute more, up to 95 for the largest one. |
| |
| ### Why those numbers |
| |
| The count of galaxies large enough to reach a given distance drops very fast: |
| 2,912 reach 10 arcsec, 499 reach 30, and only 27 reach 60. Raising the count to |
| a power compensates that drop, and `p = 4` with `Re0 = 8` is the pair that |
| flattened the histogram best in a grid search over both. |
| |
| They are **not universal constants**: they were fitted to the size distribution |
| of this catalog and must be recomputed for a different survey. |
| |
| ### Result |
| |
| | | `1pct` | `radius_norm_p4` | |
| |---|---|---| |
| | examples | 535,743 | 12,610 | |
| | examples per galaxy | 75.5 avg | 1.78 avg | |
| | median distance | 13.85″ | 9.69″ | |
| | 90th percentile | 30.42″ | 35.79″ | |
| | fullest / emptiest distance bin | **147×** | **43×** | |
| |
| Measured over 5 linear bins between 0″ and 70″, the grid used to report |
| per-distance metrics. Neither dataset leaves an empty bin. |
| |
| ### `p = 4` versus `p = 6` |
| |
| | | `radius_norm` (p=6, Re0=12) | `radius_norm_p4` (p=4, Re0=8) | |
| |---|---|---| |
| | examples | 9,246 | 12,610 | |
| | fullest / emptiest bin | 56× | **43×** | |
| | same, after balanced sampling | 8× | **7×** | |
| | effective sample size kept by that sampler | 63.4 % | **70.6 %** | |
| | worst-case repeats per epoch | 15 | **12** | |
|
|
| `p = 4` is better on every measure; it just costs 3,364 more examples. The |
| balanced sampler referenced above is the KDE sampler in `prism/sampler.py` |
| (`configs/sampler/distance_kde.yaml`). |
|
|
| ### How it was built |
|
|
| Every row here is a row of `1pct`, copied unchanged. Because both use the same |
| uniform-in-area law, keeping a **random subset** of each galaxy's rows is a |
| valid sample of that same law, so nothing had to be regenerated or re-downloaded. |
|
|
| Every cutout is centered on the **simulated** transient position, and the |
| `host_pos` label is the offset from there to the host galaxy. The `fold` column |
| is inherited from `h2f_delight_train`, so the 5-fold cross-validation split is |
| preserved and no host galaxy leaks between training and validation. |
|
|
| Note that folds are balanced by galaxy count, not by galaxy size, and `Re**4` |
| amplifies any size asymmetry between them: fold 4 ends up with 2,934 examples |
| and fold 5 with 2,250. |
|
|
| ## Image format |
|
|
| `image` has shape `(12610, 5, 1, 30, 30)`, which maps to |
| `(examples, resolution levels, photometric bands, height, width)`. Only the |
| **r band** was downloaded, hence the size-1 band dimension. |
|
|
| ## Columns |
|
|
| <div style="font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;max-width:1000px;margin:0 auto;padding:16px 0"> |
| <table style="width:100%;border-collapse:collapse;font-size:13px"> |
| <thead><tr> |
| <th style="padding:10px 7px;text-align:left;font-weight:600;border-bottom:2px solid #4a6fb5;color:#4a6fb5;font-size:14px;width:18%">Column</th> |
| <th style="padding:10px 7px;text-align:left;font-weight:500;border-bottom:2px solid #4a6fb5;color:#4a6fb5;font-size:14px;width:20%">Type</th> |
| <th style="padding:10px 7px;text-align:left;font-weight:500;border-bottom:2px solid #4a6fb5;color:#4a6fb5;font-size:14px">Description</th> |
| </tr></thead> |
| <tbody> |
|
|
| <tr><td colspan="3" style="padding:8px 12px;font-weight:600;color:#4a6fb5;border-bottom:1px solid rgba(74,111,181,0.25);background:rgba(74,111,181,0.12)">Image and label</td></tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>image</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>(5,1,30,30)</code> float32</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Multi-resolution PanSTARRS r-band cutout, centered on the simulated transient position.</td> |
| </tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>host_pos</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">float32 × 2</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Offset <code>[x, y]</code> from the simulated transient to the host galaxy, in level-0 pixels.</td> |
| </tr> |
| <tr><td colspan="3" style="padding:8px 12px;font-weight:600;color:#4a6fb5;border-bottom:1px solid rgba(74,111,181,0.25);background:rgba(74,111,181,0.12)">Identification</td></tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>oid</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">string</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Identifier of the real transient this galaxy came from. Repeats across the draws of the same galaxy.</td> |
| </tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>host_name</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">string</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Catalog name of the host galaxy.</td> |
| </tr> |
|
|
| <tr><td colspan="3" style="padding:8px 12px;font-weight:600;color:#4a6fb5;border-bottom:1px solid rgba(74,111,181,0.25);background:rgba(74,111,181,0.12)">Host galaxy</td></tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>host_redshift</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">float64</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Redshift of the host; <code>NaN</code> when unknown.</td> |
| </tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>hostsize</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">float64</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Angular size of the host galaxy from the catalog.</td> |
| </tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>host_ra</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">float64</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Right ascension of the host, in degrees.</td> |
| </tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>host_dec</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">float64</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Declination of the host, in degrees.</td> |
| </tr> |
| <tr><td colspan="3" style="padding:8px 12px;font-weight:600;color:#4a6fb5;border-bottom:1px solid rgba(74,111,181,0.25);background:rgba(74,111,181,0.12)">Real transient position</td></tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>meanra</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">float64</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Mean right ascension of the real transient, in degrees. Not the center of this cutout.</td> |
| </tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>meandec</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">float64</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Mean declination of the real transient, in degrees. Not the center of this cutout.</td> |
| </tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>sn_ra</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">float64</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Right ascension of the real supernova, in degrees.</td> |
| </tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>sn_dec</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">float64</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Declination of the real supernova, in degrees.</td> |
| </tr> |
| <tr><td colspan="3" style="padding:8px 12px;font-weight:600;color:#4a6fb5;border-bottom:1px solid rgba(74,111,181,0.25);background:rgba(74,111,181,0.12)">Sérsic fit — r band, from CasJobs</td></tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>rSerRadius</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">float64</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Effective radius Re of the r-band Sérsic fit, in arcsec. Defines the sampling region.</td> |
| </tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>rSerMag</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">float64</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Magnitude of the r-band Sérsic fit.</td> |
| </tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>rSerAb</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">float64</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Axis ratio b/a of the fitted ellipse, between 0 and 1. Defines the sampling region.</td> |
| </tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>rSerPhi</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">float64</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Position angle of the fitted ellipse, in degrees. Defines the sampling region.</td> |
| </tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>rSerRa</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">float64</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Right ascension of the Sérsic fit center, in degrees.</td> |
| </tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>rSerDec</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">float64</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Declination of the Sérsic fit center, in degrees.</td> |
| </tr> |
| <tr><td colspan="3" style="padding:8px 12px;font-weight:600;color:#4a6fb5;border-bottom:1px solid rgba(74,111,181,0.25);background:rgba(74,111,181,0.12)">Cross-validation</td></tr> |
| <tr> |
| <td style="padding:7px 7px;padding-left:20px;border-bottom:1px solid rgba(128,128,128,0.15)"><code>fold</code></td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">int64</td> |
| <td style="padding:7px 7px;border-bottom:1px solid rgba(128,128,128,0.15)">Cross-validation fold, from 1 to 5, inherited from the source galaxy.</td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| |
| ## References |
| [1] Förster, F., Muñoz Arancibia, A. M., Reyes-Jainaga, I., et al. 2022, |
| *DELIGHT: Deep Learning Identification of Galaxy Hosts of Transients using |
| Multiresolution Images*, The Astronomical Journal, 164, 195. |
| [doi:10.3847/1538-3881/ac912a](https://doi.org/10.3847/1538-3881/ac912a) |
| ```bibtex |
| @article{Forster_2022, |
| doi = {10.3847/1538-3881/ac912a}, |
| url = {https://doi.org/10.3847/1538-3881/ac912a}, |
| year = {2022}, |
| month = {oct}, |
| publisher = {The American Astronomical Society}, |
| volume = {164}, |
| number = {5}, |
| pages = {195}, |
| author = {F\"orster, Francisco and Mu\~noz Arancibia, Alejandra M. and Reyes-Jainaga, Ignacio and Gagliano, Alexander and Britt, Dylan and Cuellar-Carrillo, Sara and Figueroa-Tapia, Felipe and Polzin, Ava and Yousef, Yara and Arredondo, Javier and Rodr\'iguez-Mancini, Diego and Correa-Orellana, Javier and Bayo, Amelia and Bauer, Franz E. and Catelan, M\'arcio and Cabrera-Vives, Guillermo and Dastidar, Raya and Est\'evez, Pablo A. and Pignata, Giuliano and Hern\'andez-Garc\'ia, Lorena and Huijse, Pablo and Reyes, Esteban and S\'anchez-S\'aez, Paula and Ram\'irez, Mauricio and Grand\'on, Daniela and Pineda-Garc\'ia, Jonathan and Chabour-Barra, Francisca and Silva-Farf\'an, Javier}, |
| title = {DELIGHT: Deep Learning Identification of Galaxy Hosts of Transients using Multiresolution Images}, |
| journal = {The Astronomical Journal}, |
| } |
| ``` |
