TITLE:   GCN CIRCULAR
NUMBER:  45361
SUBJECT: GRB 260809A: SAO RAS optical observations
DATE:    26/08/12 11:58:37 GMT
FROM:    Alexander Moskvitin at SAO RAS <mosk@sao.ru>

A. Moskvitin (SAO RAS), N. Pankov (IKI), A. Pozanenko (IKI),
A. Volnova (IKI), O. Spiridonova (SAO RAS)
report on behalf of GRB follow-up team

We observed the field of the GRB 260809A discovered by the SVOM
(Brunet et al., GCN 45331), also detected by EP-FXT (Sun et al.,
GCN 45344) with the Zeiss-1000, SAO RAS 1-m telescope + CCD photometer
on 2026-08-09T23:20:36--2026-08-10T00:49:19 UT (t_mid = 9.1234 hours).

The OT (Li et al., GCN 45336; Adami et al., GCN 45338; Rajabov et al.,
GCN 45339;  Izzo, Saccardi and Corcoran, GCN 45340; Basa et al.,
GCN 45342) is clearly detected in our stacked image.
Details of the observation are the following.

Date,      UTstart, t-T0,   Exp.,  Filter, Mag,     Err.,     UL
                    (mid,d) (n*s)                          (3-sigma)
2026-08-09 23:20:36 0.38014 14*300 Rc      22.60 +/- 0.17  23.4

This preliminary photometry (Vega) is based on nearby SDSS stars
(Lupton 2005 transformation) and not corrected for Galactic extinction.