TITLE:   GCN CIRCULAR
NUMBER:  40828
SUBJECT: GRB 250625A: SAO RAS possible optical afterglow
DATE:    25/06/25 21:47:40 GMT
FROM:    Alexander Moskvitin at SAO RAS <mosk@sao.ru>

A. Moskvitin, O. Spiridonova (SAO RAS),
report on behalf of a GRB follow-up collaboration.

We observed the field of the GRB 250625A (The Fermi GBM team, 
GCN 40824; Ferro et al., GCN 40825) with SAO RAS 1-m telescope 
Zeiss-1000 equipped with CCD-photometer. We obtained 6 x 300 sec. 
exposures in Rc band on June 25, 20:39:03--21:12:11 UT 
(t_mid - T0 = 4.8447 hours).

Withtin the enhanced XRT error circle (Beardmore et al., GCN 40827) 
we detect single object with the coordinates:
R.A. (J2000.0) =  17:26:02.1
Dec. (J2000.0) = +22:16:03.6 +/- 0".3
and brightness of R = 22.97 +/- 0.17, possible GRB OT.
Observations are ongoing to confirm variability of the object.

Preliminary photometry is based on the nearby USNO-B1.0 
and has not corrected for the Galactic extinction.

R.A.       Dec. (2000)   R2
17:26:06.4 +22:16:29.4   14.75
17:26:03.7 +22:15:09.9   15.42
17:26:10.0 +22:13:56.8   15.03
17:26:01.4 +22:18:39.0   14.59