TITLE:   GCN CIRCULAR
NUMBER:  36273
SUBJECT: LIGO/Virgo/KAGRA S240422ed: DECam GW-MMADS Candidates
DATE:    24/04/24 04:58:04 GMT
FROM:    Antonella Palmese at Carnegie Mellon University <apalmese@andrew.cmu.edu>

Lei Hu (CMU), Tomás Cabrera (CMU), Brendan O'Connor (CMU), Igor Andreoni (UMD), Antonella Palmese (CMU), Keerthi Kunnumkai (CMU) report on behalf of the GW-MMADS team:


We continued the follow-up of the LIGO/Virgo/KAGRA event S240422ed (GCN 36236, GCN 36240) with DECam as part of the GW-MMADS survey program (Palmese et al., GCN 36245). New pointings taken between 2024-04-23 23:15 and 2024-04-24 03:46 UTC have been reported to the TreasureMap (Wyatt et al., 2020): https://treasuremap.space/alerts?graceids=S240422ed

We ran the SFFT difference imaging (Hu et al. 2022) on the available images from the first night of observations (between 2023-04-22 23:37 and 2024-04-23 03:40 UTC; GCN 36245), filtered out likely stars and moving objects, and visually inspected the remaining transients. 

We reported on TNS new transients within the LVK 95% CI area, and report here the candidate counterparts with at least two detections and possibly associated with a low-redshift galaxy from the NED LVS catalog (Cook et al. 2023):

+-------------------------+------------+------------+-----------+-----------+
| id                      | tns        |       ra   |      dec  | comment   |
|-------------------------+------------+------------+-----------+-----------|
| T202404230842302m153558 | AT 2024hdk | 130.625724 | -15.59953 |           |
| T202404230829126m213023 | AT 2024hdn | 127.302473 | -21.50639 |           |
| T202404230826379m205002 | AT 2024hdm | 126.65801  | -20.83375 |           |
| T202404230821534m300608 | AT 2024hdl | 125.472700 | -30.10220 |  *        |
| T202404220803280m260044 | AT 2024hdo | 120.866797 | -26.01212 |           |
| T202404220803131m241958 | AT 2024hdr | 120.804560 | -24.33268 |  nuclear  |
| T202404220802104m271528 | AT 2024hdp | 120.543455 | -27.25787 |           |
| T202404220743147m254551 | AT 2024hdq | 115.811388 | -25.76403 |  nuclear  |
+-------------------------+------------+------------+-----------+-----------+

* This object was detected in 2 observations separated by <15 min and cannot be excluded as a moving object.

Further data reduction is underway.

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