TITLE: GCN CIRCULAR NUMBER: 43351 SUBJECT: GRB 260102A: AbAO optical observations DATE: 26/01/08 14:28:34 GMT FROM: Nicolai Pankov at IKI <colinsergesen@gmail.com> N. Pankov (IKI), A. Pozanenko (IKI), R. Ya. Inasaridze (AbAO), A. Volnova (IKI) report on behalf of IKI-GRB-FuN: We performed optical observations of the field of GRB 260102A (XIE et. al, GCN 43295; Evans, GCN 43298; Bernardini et. al, GCN 43304; Yin et. al, GCN 43307; Hamburg, GCN 43308) in the R-filter with the 0.7-meter AS-32 telescope of Abastumani Observatory (AbAO). Two epochs of observations were taken, the first one began on 2026-01-02 19:21:22 UT, i.e. ~0.65 days since trigger. The optical counterpart (Wu et. al, GCN 43300) was not detected in the co-add images of both epochs. The preliminary upper limits and the observation details are given below: Date UT start t-T0 Exp. Filter OT Err. UL (mid, days) (s) (3sigma) 2026-01-02 19:21:22 0.65786 72*60 R n/d n/d 20.1 2026-01-03 19:22:18 1.65850 72*60 R n/d n/d 19.8 The photometry was calibrated using nearby stars from USNO-B1.0 and was not corrected for the Galactic extinction. The obtained results do not contradict the optical upper limits from other groups (Antier et. al, GCN 43303; Saccardi et. al, GCN 43305). View this GCN Circular online at https://gcn.nasa.gov/circulars/43351. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...