GCN Circular 31837
Subject
GRB 220403B: Kitab optical observations
Event
Date
2022-04-05T21:24:30Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
N. Pankov (HSE), A. Zhornichenko (KIAM), A. Pozanenko (IKI), V.
Agletdinov (KIAM), S. Belkin (IKI), Sh. Ehgamberdiev (UBAI) report on
behalf of IKI-GRB-FuN:
We observed the field of GRB 220403B (Klingler et al., GCN 31820)
with Kitab RC-36 telescope in Clear filter. Observation started on
April, 03 (UT) 21:23:55 and ended on April, 04 (UT) 00:00:11. We
clearly detect the optical afterglow (Klingler et al., GCN 31820;
Jelinek et al., GCN 31821; Zhu et al., GCN 31823; Rossi et al., GCN
31826; see also early upper limits in Lipunov et al., GCN 31825; Grossan
et al., GCN 31830) in the combined images of an initial part of
observations and do not detect it in the final part.
Preliminary photometry of the combined images is following
Date, UT start, t-T0, Exp., Filter, OT, Err, UL(3 sigma)
(mid, days)
2022-04-03 21:23:55 0.05178 40*60 CR 19.24 0.19 20.2
2022-04-03 22:30:39 0.10640 87*60 CR n/d n/d 20.5
The photometry is based on nearby USNO-B1.0 stars, R2 magnitude
USNO-B1.0_id R2
1791-0003982 16.77
1791-0003984 17.83