TITLE: GCN CIRCULAR NUMBER: 39355 SUBJECT: LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7 DATE: 25/02/17 20:20:56 GMT FROM: Alexei Pozanenko at IKI, Moscow grb.alex@gmail.com

A. Pozanenko (IKI, HSE), A. Volnova (IKI), N. Pankov (HSE, IKI), R. Ya. Inasaridze (AbAO) report on behalf of IKI GRB-FuN collaboration:

We continue to observe galaxies from the NED/GLADE+ catalogs in the localization volume S250206dm (LIGO Scientific Collaboration, GCN 39175; LIGO Scientific Collaboration, GCN 39184). We observed several galaxies with AS-32 telescope of the Abastumani Observatory (AbAO) in the R-filter. The observations consist of 3 exposures in R-filter of each galaxy in the on Feb., 12 and Feb. 16. In the first epoch of observations near the galaxy WISEA J021210.14+514821.7 we clearly detected an optical source which is not present in the PS1 catalog. The source is visible in each of the 3 exposures. The source is not detected in the following epoch on February 16. Preliminary photometry of stacked images is the following

Date |UTstart |t-T0* |MJD_mid |Exp. |Filter|OT |Err |UL |FWHM | |(mid, days)| |(n*s) | | | |(3sigma)|" ---------------------------------------------------------------------------- 2025-02-12|15:46:10| 5.76573|60718.65844| 3*60 |R |18.15|0.21|19.0 |3.1 2025-02-16|15:57:48| 9.77361|60722.66632| 3*60 |R | n/d |n/d |19.1 |3.0 * - T0 = 21:25:30.439 UTC LIGO trigger time of S250206dm

Photometry is based on nearby stars from USNO-B1.0: ID RA Dec R2 1418-00067499 02:12:12.126 +51:49:52.59 14.68 1418-00067498 02:12:12.025 +51:48:41.88 14.94 1418-00067549 02:12:18.069 +51:48:21.33 13.93

The source coordinates are (J2000) 02:12:10.17 +51:48:21.54, and the offset from the center of the galaxy is 6.2", which is equivalent to 11 kpc at a luminosity distance of DL = 457 Mpc (GLADE+).

We have not observed this galaxy before, so we cannot say anything about the nature of this source and further observations and analysis of further observations of this galaxy are needed.

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