TITLE:   GCN CIRCULAR
NUMBER:  34039
SUBJECT: LIGO/Virgo/KAGRA S230615az: Wendelstein observations of DESI galaxies and GIT candidates
DATE:    23/06/20 14:55:35 GMT
FROM:    Antonella Palmese at Carnegie Mellon University <apalmese@andrew.cmu.edu>

Anisha Anisha (LMU/University of Hamburg), Julius Gassert (LMU), Daniel Gruen (LMU), Lei Hu (Purple Mountain Observatory/Carnegie Mellon U.), Antonella Palmese (Carnegie Mellon U.), Arno Riffeser (LMU/MPE), Ananya Shankar (LMU)

With the 3kk imager at the 2m Fraunhofer telescope at Wendelstein Observatory, Germany, we have observed the highest probability candidate host galaxies based on their sky position and DESI spectroscopic redshift with respect to the 3D localization of event S230615az. Observations took place between MJD 60110.8 and MJD 60110.9, 3-4 hours after the gravitational wave candidate event. Using Legacy Survey DR10 imaging as a template where available, we perform difference imaging and do not detect any viable candidate counterparts. We report the following upper limits within a ~7’x7’ field around the given coordinates:

RA(J2000) [deg] | dec(J2000) [deg] | date_obs [UTC] | filters | lim_mag(AB, 5sigma) 
167.3605 | 29.5734 | 2023-06-15T21:27:32.858393 | r,i | 22.9, 22.7
167.6634 | 28.3207 | 2023-06-15T21:48:52.763590 | r,i | 22.6, 22.6
167.7216 | 30.1690 | 2023-06-15T21:38:13.808422 | r,i | 22.8, 22.6
168.0171 |  27.5943 | 2023-06-15T21:16:55.039852 | r,i | 22.7, 22.5
169.5725, 28.2641 | 2023-06-15T23:10:35.119420 | r,i | 22.6, 22.3
174.2707 | 24.1003 | 2023-06-15T21:59:32.521545 | r,i | 22.3, 22.3
175.6390 | 26.4931 | 2023-06-15T20:48:24.528448 | r,i | 22.6, 22.3
149.4729| 36.3526 | 2023-06-15T21:06:05.721774 | r,i | 22.3, 22.3

We have also followed up the GROWTH-India candidate counterparts reported by GCN 33974 consistent with the gravitational wave event S230615az. We report the following upper limits:

Name | date_obs [UTC] | filters | lim_mag(AB, 5sigma) 
GIT230615aa | 2023-06-15T22:29:56.229398 | r | 22.7
GIT230615ab | 2023-06-15T22:38:41.867278 | g | 21.9
GIT230615ab |2023-06-15T22:47:20.897141| r | 22.7

Magnitudes are not corrected for Milky Way extinction.