TITLE:   GCN CIRCULAR
NUMBER:  36153
SUBJECT: LIGO/Virgo/KAGRA S240413p: DECam GW-MMADS candidates
DATE:    24/04/18 03:51:55 GMT
FROM:    Antonella Palmese at Carnegie Mellon University <apalmese@andrew.cmu.edu>

LIGO/Virgo/KAGRA S240413p: DECam GW-MMADS candidates

Antonella Palmese (CMU), Lei Hu (CMU), Tomás Cabrera (CMU), Igor Andreoni (UMD), Malte Busman (LMU), Saavik Ford (AMNH/CUNY), Julius Gassert (LMU), Matthew Graham (Caltech), Daniel Gruen (LMU), Brendan O'Connor (CMU), Jake Postiglione (CUNY), Julian Sommer (LMU) report on behalf of the GW-MMADS team:

The high probability area of the LVK gravitational wave candidate S240413p (GCN 36075, 36082) was observed using the wide-field Dark Energy Camera (DECam) on the 4m Blanco telescope, as part of the “Search, discovery and follow up of electromagnetic counterparts of gravitational wave events” program
(PI: Soares-Santos). We reduced exposures taken starting at 2024-04-16 00:53 UTC on the first night and 2024-04-16 23:25 UTC on the second night of the follow-up. The first night’s observations covered r and i band, and the second night’s observations were performed in i band. 

We run the SFFT difference imaging (Hu et al. 2022) on the available images, filter out likely stars and moving objects, and visually inspect the remaining transients. We report new transients within the LVK 99% CI area that we do not currently exclude as candidate counterparts based on available redshift information. 

+-------------------------+----------+----------+------------+-------------+-----------+
| id                      |       ra |    dec   | mjd        | mag±err (ab)| filter    |
|-------------------------+----------+----------+------------+-------------+-----------|
| C202404161101539p095533 | 165.4746 | 9.9258   | 60416.04736 | 21.31±0.08 | i         |
| T202404161055381p073155 | 163.9089 | 7.5319   | 60416.15488 | 21.14±0.08 | i         |
| T202404161035468p033742 | 158.9451 | 3.6284   | 60416.09484 | 21.41±0.04 | r         |
| T202404161046169p084925 | 161.5702 | 8.8237   | 60416.13789 | 21.2±0.05  | i         |
| T202404161030235p040944 | 157.5978 | 4.1621.  | 60416.13357 | 21.43±0.06 | i         |
|-------------------------+----------+----------+------------+-------------+-----------+

Further inspection of candidate counterparts is underway.