GCN Circular 42698

Subject

LIGO/Virgo/KAGRA S251112cm: AT2025adht follow-up at Maidanak observatory by GRANDMA

Event

LIGO/Virgo/KAGRA S251112cm

Date

2025-11-15T13:54:03Z (6 days ago)

From

Yodgor Rajabov at UBAI <rajabov@astrin.uz>

Via

Web form

O. Burkhonov, Y. Rajabov, Y. Tillayev (UBAI), P. Hello (IJCLAB), A. Klotz (IRAP), M. Coughlin (UMN), S. Karpov (FZU), M. Pillas (IAP), M. Mazek (FZU ), S. Antier (IJCLAB), O. Pyshna (Caltech) on behalf of GRANDMA:

We detected transient event 2025adht in RA_J2000=12:00:24.3431, Dec_J2000=+49:02:51.7 reported by (GCN 42677Loading...
 
  Anand et al., Franz GCN 42675Loading...
 
  et al.,). Observations were carried out at the 1.5-meter telescope Maidanak Observatory by using 4Kx4K SNUCAM CCD. All observations were taken using a Bessel R filter. The observations started at 2025-11-15T00:13:15 UTC and ended at 2025-11-15T00:40:17 UTC. A total of 6 CCD images with an exposure of 300 seconds were obtained.

Despite the fact that this object is located far from the equator, we checked for the presence of small bodies in this region using the small body database from 14 November 2025.  The check was negative. Cross-identification results indicated the same galaxy without any transient events: DSS J120024.56+490254.3, WISEA J120024.53+490254.1, and GALEXASC J120024.49+490252.9.
We analyzed our data using our standard pipeline and with STDWeb/STDPipe (Karpov, 2025). We present stacked results after galaxy soustraction.
 
       MJD    | DATE-OBS          |  MAG |M_ERR|U.L.|FILTER| Telescope| MAG system
--------------------------------------------------------------------------------------
60994.00920139 | 2025-11-15 00:29 | 21.54|0.1|22.10|R|UBAI/AZT-22|Vega, Gaia DR3

Which has an equivalent using PS1 of 21.64+/- 0.1 in sdssr using PS1 (color term 0.13).

More observations are planned.
 
GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/). Maidanak astronomical observatory (MAO) is an observational facility of the Ulugh Beg Astronomical Institute (UBAI), Uzbekistan Academy of Sciences (http://maidanak.uz/).