GCN Circular 30488
Subject
GRB 210722A: Kitab optical observations, light curve
Event
Date
2021-07-23T17:59:25Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
N. Pankov (IKI, HSE), A. Zhornichenko (KIAM), A. Pozanenko (IKI), V.
Agletdinov (KIAM), M. Krugov (FAI), V. Kim (FAI), S. Belkin (IKI), Sh.
Ehgamberdiev (UBAI) report on behalf of IKI-GRB-FuN:
We observed the field of GRB 210722A (D'Avanzo et al., GCN 30475) with
Kitab-ISON RC-36 telescope in Clear filter. Observation started on
July, 22 (UT) 21:31:44 and ended on July, 22 (UT) 23:20:06. We clearly
detect the bright optical afterglow (D'Avanzo et al., GCN 30475; Zhu et
al., GCN 30476; Pankov et al., GCN 30478; Lipunov et al., GCN 30480;
Kumar et al., GCN 30481; Siegel et al., GCN 30421; Butler et al., GCN
30484).
Preliminary photometry of the first and latest combined images are following
Date, UT start, t-T0, Exp., Filter, OT, Err, UL(3 sigma)
(mid, days)
2021-07-22 21:31:44 0.02572 5*60 CR 16.00 0.15 18.4
2021-07-22 23:13:54 0.09667 7*60 CR 17.33 0.12 19.0
The photometry is based on nearby USNO-B1.0 stars, R2 magnitude.
USNO-B1.0_id R2
USNO_B10-0836-00016699
USNO_B10-0836-00016715
We approximate the light curve by single PL model with power law index
of -1.1 which is corroborating with PL index reported by Kumar et al.
(GCN 30481). The light curve of our observations in Assy (Pankov et
al., GCN 30478) and Kitab observatory can be found at
http://grb.rssi.ru/GRB210722A/GRB210722A_LC.jpeg