GCN Circular 30530
Subject
GRB 210725A: AbAO optical upper limit
Date
2021-07-27T06:54:14Z (3 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
N. Pankov (HSE, IKI), R. Ya. Inasaridze (AbAO), A. Pozanenko (IKI),
S. Belkin (IKI), V. R. Ayvazian (AbAO), G. V. Kapanadze (AbAO), report
on behalf of GRB IKI FuN:
We observed the field of GRB 210725A (Bernardini et al. GCN 30501;
Torii et al. GCN 30507; Poolakkil et al. GCN 30519) with AS-32
telescope of Abastumani observatory (AbAO) in R-filter starting on July,
25 (UT) 19:11:58. We do not detect any object in the enhanced XRT
position (Perri et al. GCN 30517). The non detection is consistent with
optical observations (Zheng et al. GCN 30503; Niwano et al., GCN 30509;
Siegel et al. GCN 30527).
Preliminary photometry of the field is following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2021-07-25 19:11:58 0.65481 R 36*60 n/d n/d 20.8
The photometry is based on the nearby stars:
USNO-B1.0 R2
USNO_B10_id R2
0888-00234198 14.31
0888-00234167 15.25