TITLE: GCN CIRCULAR NUMBER: 42710 SUBJECT: GRB 251111A: Mondy optical upper limit DATE: 25/11/17 08:05:29 GMT FROM: Alina Volnova at IKI RAS <alinusss@gmail.com> A. Volnova (IKI), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We observed the field of the GRB 251111A (Cheng et al., GCN 42637) with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy) in the R-filter starting Nov., 11, 2025, UT 16:26:22, and taking several frames with 120 s exposures. In the stacked frame we do not detect the optical counterpart (López-Cámara et al., GCN 42638; Wu et al., GCNs 42639, 42641; Ma et al., GCN 42647). Preliminary photometry is the following: Date UT start t-T0 Exp. Filter OT Err. UL (mid,days) (n*s) (3sigma) 2025-11-11 16:26:22 0.48686 25*120 R n/d n/d 22.1 The photometry is based on several nearby SDSS stars (R-magnitudes Lupton's transformation) and is not corrected for the Galactic extinction, all magnitudes are in Vega system. View this GCN Circular online at https://gcn.nasa.gov/circulars/42710. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...