GCN Circular 43062
Subject
GRB 251129A/EP251129a: AbAO and Mondy optical observations
Event
Date
2025-12-10T09:30:07Z (4 days ago)
From
Alina Volnova at IKI RAS <alinusss@gmail.com>
Via
Web form
N. S. Pankov (HSE, IKI), E. Klunko (ISTP), R. Ya. Inasaridze (AbAO), A. A. Volnova (IKI), A. S. Pozanenko (IKI) report on behalf of IKI-GRB-FuN:
We observed the field of GRB 251129A initially detected by SVOM (Tan et al., GCN 42877) and also detected by Einstein Probe as EP251129a (Wu et al., GCN 42884) and Swift (Evans, GCN 42888; Page et al., GCN 42891). The observations were carried out with the AS-32 0.7m telescope of the Abastumani Observatory (AbAO) and the 1.5m telescope of the Sayan Solar Observatory (Mondy). The observations started on 2025-11-29 at 18:58 UT at AbAO. The optical afterglow (Angulo et al., GCN 42880; Wu et al., GCN 42882; Watson, GCN 42883; Masi, GCN 42885; Li et al., GCN 42887; Lipunov et al., GCN 42892; Moskvitin & Spiridonova, GCN 42897; Guziy et al., GCN 42899; Sanchez-Ramirez et al., GCN 42900; Yaqup et al., GCN 42942; Kuin and Cenko, GCN 42959; Xin et al., GCN 42972) is only visible in the stacked images from Mondy. The preliminary photometry and the observation properties are presented above:
Date UT start t-T0 Exp. Filter OT Err. UL Site/Telescope
(mid,days) (n*s) (3sigma)
2025-11-29 18:58:15 0.70255 51*60 R n/d n/d 17.6 AbAO/AS-32
2025-11-29 20:15:26 0.75928 30*120 R 21.57 0.15 22.2 Mondy/AZT-33IK
2025-11-30 19:50:56 1.75199 44*120 R 21.47 0.13 22.2 Mondy/AZT-33IK
The photometry is based on nearby stars from the USNO-B1 catalog (R2 magnitudes) and is not corrected for the Galactic extinction.