GCN Circular 42475
Subject
GRB 251025B: Mondy optical observations
Event
Date
2025-10-27T13:31:43Z (2 days ago)
From
Alina Volnova at IKI RAS <alinusss@gmail.com>
Via
Web form
A. Volnova (IKI), A. Pozanenko (IKI) , N. Pankov (HSE, IKI), E. Klunko (ISTP) report on behalf of IKI-GRB-FuN:
We observed the field of the GRB 251025B (Hussein et al., GCN 42437) in the R-filter with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy) starting Oct. 26, 2025, 16:25:44 UT, and taking several frames with 120 s exposures. The optical counterpart (Wu et al., GCN 42438; Gress et al., GCN 42439; Wu et al., GCN 42440; Beardmore et al., GCN 42445; Mohan et al., GCN 42447; Hernández Funget al., GCN 42450; Pereyra et al., GCN 42452; Li et al., GCN 42453; Mo et al., GCN 42459; Rakotondrainibe et al., GCN 42460; Rajabov et al., 42466; Saccardi et al., 42472; Freeberg et al., 42474) is clearly detected in the stacked frame. Preliminary photometry is the following:
Date UT start t-T0 Exp. Filter OT Err. UL
(mid,days) (n*s) (3sigma)
2025-10-26 16:25:44 1.10532 60*120 R 20.50 0.05 23.1
The photometry is based on several nearby SDSS stars (R-magnitudes Lupton's transformation) and is not corrected for the Galactic extinction.