TITLE:   GCN CIRCULAR
NUMBER:  46062
SUBJECT: GRB 261026A: SAO RAS optical observations
DATE:    26/10/27 16:49:43 GMT
FROM:    Alexander Moskvitin at SAO RAS <mosk@sao.ru>

A. Moskvitin (SAO), V. Goranskij (SAI MSU, SAO), V. Vlasyuk (SAO),
A. Volnova (IKI), N. Pankov (IKI), A. Pozanenko (IKI),
on behalf of the SAO GRB follow-up team and the IKI-GRB-FuN report.

We observed the field of GRB 261026A discovered by SVOM (Goto et al.,
GCN 46030), also detected by EP-FXT (Jiang et al., GCN 46058)
with the SAO RAS 1-m Zeiss-1000 and 0.5-m AS-500(2) telescopes
on October 26.

The OT (Dornic et al., GCN 46033; Zheng et al., GCN 46034; Wu et al.,
GCN 46035; Li et al., GCN 46046; Morín-González et al., GCN 46048;
Coyo et al., GCN 46054; also observed in NIR, Mohan et al., GCN 46041;
Shi et al., GCN 46047) is detected only in the Zeiss-1000 stacked frame.
Details of the observation are the following.

Date        UT start  t-T0      Exp,    Filter Obj     Err   UL
 Telescope
                     (mid,days) (n*s)                       (3sigma)
2026-10-26  20:11:58  0.59342   4*300   Rc     21.5 +/- 0.2  22.1
 Zeiss-1000
2026-10-26  20:41:16  0.61058   30*30   R      n/d      n/d  20.5    AS-500
(2)

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