TITLE:   GCN CIRCULAR
NUMBER:  46110
SUBJECT: GRB 261026A: Mondy, SAO RAS and Terskol optical observations
DATE:    26/10/30 13:09:20 GMT
FROM:    Alexander Moskvitin at SAO RAS <mosk@sao.ru>

A. Moskvitin (SAO), O. Spiridonova (SAO), E. Klunko (ISTP), D. Andreev
(INASAN),
I. Sokolov (INASAN), 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;
Xie et al., GCN 46068), also detected by EP-FXT (Jiang et al., GCN 46058)
with AZT-33IK 1.5-m telescope of the Sayan Solar Observatory (Mondy)
1-m Zeiss-1000 telescope of SAO RAS and 2-m Zeiss-2000 telescope
of the Terskol Observatory (INASAN).

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;
Moskvitin et al., GCN 46062; Li et al., GCN 46063; also observed in NIR:
Mohan et al., GCN 46041; Shi et al., GCN 46047; Manyan et al., GCN 46064)
is detected in our stacked frames. Details of the observation are the
following.

Date        UT start  t-T0      Exp,    Filter Obj      Err   UL
Obs./Tel.
                     (mid,days) (n*s)                         (3sigma)
2026-10-27  13:27:57  1.37418   36*120  R      21.8 +/- 0.2   22.5
Mondy/AZT-33IK
2026-10-27  17:03:29  1.48441   36*100  Rc     22.0 +/- 0.2   22.6
SAO/Zeiss-1000
2026-10-28  19:20:41  2.58316   40*100  Rc     22.7 +/- 0.3   22.7
SAO/Zeiss-1000
2026-10-28  20:37:22  2.62112   17*180  R      23.0 +/- 0.3   23.1
Terskol/Zeiss-2000

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