TITLE:   GCN CIRCULAR
NUMBER:  29634
SUBJECT: GRB 210308A: Mondy and AbAO optical observations
DATE:    21/03/09 06:13:56 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), N. Pankov (HSE), A. Pozanenko (IKI), E. Klunko (ISTP), 
R. Ya. Inasaridze (AbAO), V. R. Ayvazian (AbAO),  G. V. Kapanadze 
(AbAO), D. G. Datashvili (AbAO) report on behalf of IKI-GRB-FuN:

We observed the field of  GRB 210308A (D'Elia et al., GCN 29619) with 
AZT-33IK telescope of Sayan observatory (Mondy) starting on  2021-03-08 
(UT) 13:00:45 and AS-32 telescope of Abastumani observatory (AbAO) 
starting on  2021-03-08 (UT) 16:32:07 (both in R-filter). The optical 
afterglow (D'Elia et al., GCN 29619; Gropp et al., GCN 29630; see also 
Ogata et al., GCN 29621; Zhu et al., GCN 29623; Lipunov et al., GCN 
29627) is detected in stacked image of AZT-33IK and not detected at AS-32.

Date       UT start   t-T0    Filter  Exp.   OT    Err.  UL(3sigma)
                        (mid, days)     (s)

2021-03-08 13:00:45   0.27626  R      15*120 22.77  0.27 22.8 AZT-33IK
2021-03-08 16:32:07   0.42131  R      25*60  n/d    n/d  21.8 AS-32

The photometry is based on nearby USNO-B1.0 stars
USNO-B1.0_id R2
1274-0090800 15.34
1274-0090824 17.35