TITLE: GCN CIRCULAR NUMBER: 39985 SUBJECT: GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits DATE: 25/03/31 19:48:32 GMT FROM: Alexei Pozanenko at IKI, Moscow <grb.alex@gmail.com> N. Pankov (HSE, IKI), A. Pozanenko (IKI), E. Klunko (ISTP), R. Ya. Inasaridze (AbAO), A. S. Moskvitin (SAO RAS), O. I. Spiridonova (SAO RAS), Yu. V. Sotnikova (SAO RAS), A. Ghosh (CAPP, University of Johannesburg), S. Razzaque (CAPP, University of Johannesburg) and IKI GRB-FuN report We observed the field of GRB 250329A (Wang et al., GCN 39916; Dichiara et al., GCN 39924) in the R filter with the 0.7-meter AS-32 telescope of the Abastumani Observatory (AbAO), in the R filter with the 1.5-meter AZT-33IK telescope of the Sayan Solar Observatory (Mondy) and in the Rc filter with the 1-meter Zeiss-1000 of SAO RAS. We do not detect the OT (Watson et al., GCN 39915; Wang et al., GCN 39917; Schneider et al., GCN 39918; Ghosh et al., GCN 39922; Ferro et al., GCN 39927) down to the following limits. Date UT start t-T0 Filter Exp. UL(3sigma) Telescope (mid, d) (s) 2025-03-29 17:07:10 0.56824 R 98 x 60 21.7 AS-32 2025-03-29 19:11:57 0.64726 R 38 x 120 22.7 AZT-33IK 2025-03-29 20:00:02 0.66837 Rc 7 x 300 22.3 Zeiss-1000 Photometry is based on nearby USNO-B1.0 stars and is not corrected for Galactic extinction RA Dec R2 197.4269 9.4669 15.26 197.4732 9.4981 13.49 197.4408 9.5091 15.64 View this GCN Circular online at https://gcn.nasa.gov/circulars/39985. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...