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GCN Circular 36298

LIGO/Virgo/KAGRA S240422ed: Additional DECam GW-MMADS Candidates from the first two nights of observations
2024-04-25T04:11:50Z (3 months ago)
Tomas Cabrera <>
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Tomás Cabrera (CMU), Lei Hu (CMU), Igor Andreoni (UMD), Keerthi Kunnumkai (CMU), Brendan O'Connor (CMU), Antonella Palmese (CMU), Robert Stein (Caltech), Tomás Ahumada (Caltech), Mattia Bulla (Ferrara) report on behalf of the GW-MMADS team:

We report new candidates from the DECam GW-MMADS survey program (GCN 36245, GCN 36273) follow-up of the LIGO/Virgo/KAGRA event S240422ed (GCN 36236, GCN 36240).

We ran the SFFT difference imaging (Hu et al. 2022) on images from the second night of observations (between 2024-04-23 23:15 and 2024-04-24 03:46 UTC) where archival images were available for use as templates. We filtered out likely stars, moving objects, and recent transients from the ZTF survey. We visually inspected the remaining transients.

We reported on TNS new transients within the LVK 95% CI area, and report here new candidate counterparts possibly associated with a host galaxy:

|           id            |    tns     |     ra     |     dec    | comment |
| C202404240825089m244346 | AT 2024hfq | 126.286902 | -24.729418 |   [1]   |
| T202404230841039m183535 | AT 2024hfr | 130.266165 | -18.593131 |   [2]   |
| T202404230828385m202260 | AT 2024hfs | 130.266165 | -18.593131 |         |

[1] - This source is within 0.4 arcsec of the galaxy WISEA J082508.82-244345.9.
[2] - This source is within 0.3 arcsec from the object WISEA J084103.91-183532.4.  This galaxy has a 2MASS photometric redshift (Bilicki et al. 2014) of 0.049.

None of these transients shows a fast (> 0.3 mag/day) rise or fade in their light curves from preliminary photometry. GW-MMADS DECam transients reported yesterday in GCN 36273 do not show a rapid evolution (> 0.3 mag/day) in z- or r-band between the first and second night of observations.

We thank the CTIO and NOIRLab staff for supporting these observations and the data calibrations.
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