TITLE:   GCN CIRCULAR
NUMBER:  46149
SUBJECT: GRB 260924A: CrAO ZTSh optical observations
DATE:    26/11/04 15:10:11 GMT
FROM:    Alexander Moskvitin at SAO RAS <mosk@sao.ru>

A. Moskvitin (SAO), V. Rumyantsev (CrAO), N. Pankov (IKI),
A. Volnova (IKI), A. Pozanenko (IKI) report on behalf of SAO GRB
follow-up team and IKI GRB-FuN.

We observed the field of the GRB 260924A discovered by Fermi
(The Fermi GBM team, GCN 45712; Holzmann Airasca et al., GCN 45721;
McDermott et al., GCN 45723), Swift (D'Elia et al., GCN 45713;
Evans et al., GCN 45715; Dichiara et al., GCN 45730; Gupta et al.,
GCN 45733), AstroSat CZTI (Salunke et al., GCN 45720), NuSTAR
(Waratkar and Grefenstette, GCN 45732), SVOM (Yu et al., GCN 45741),
Konus-Wind (Ridnaia et al., GCN 45751) with the Shajn 2.6-m telescope
(ZTSh) of CrAO on 2026-10-04T01:17:57--2026-10-04T02:42:40 UT.

The OT (Hu et al., GCN 45717; Izzo et al., GCN 45718;
Vijaykumar et al., GCN 45734; Klingler and D'Elia, GCN 45735;
Castro-Tirado et al., GCN 45740; Novotny et al., GCN 45743;
Aryan et al., GCN 45748; Fortin et al., GCN 45759; Pankov et al.,
GCN 45774; Kuin et al., GCN 45775; also observed in NIR:
Ma et al., GCN 45736; Mo et al., GCN 45762; and in radio:
Gulati et al., GCN 45776) is marginally detected in our
stacked image. The observation details are as follows:

Date       UT start  t-T0       Exp,    Filter Obj      Err   UL
                     (mid,days) (n*s)                         (3sigma)
2026-10-04 01:17:57  10.03259   40*120  R      22.8 +/- 0.3   23.1

This preliminary photometry (Vega) is based on nearby USNO-B1.0
stars and not corrected for the Galactic extinction.