GCN Circular 30972
Subject
GRB 211023B: TSHAO optical observation
Event
Date
2021-10-24T13:54:08Z (5 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Pozanenko (IKI), I. Reva (FAP), M.Krugov (FAP), S. Belkin (IKI), V.
Kim (FAP), N. Pankov (HSE) report on behalf of GRB-IKI-FuN:
We observed the field of possible short GRB 211023B detected by Swift
(Dichiara et al., GCN 30960) with Zeiss-1000 telescope of Tien Shan
Astronomical Observatory stating on Oct. 23 (UT) 21:17:06. We obtained
series with 120 sec expositions in R-filter.
Within enhanced Swift-XRT position (Beardmore et al., GCN 30966) we do
not detected any source (see upper limits below). In particular we do
not detect possible optical afterglow (Dichiara et al., GCN 30960).
Preliminary photometry of stacked images is following
Date UT start t-T0 Filter Exp. OT Err. UL(3 sigma)
(mid, days) (s)
2021-10-23 21:17:06 0.01127 R 5*120 n/d n/d 18.9
2021-10-23 21:17:06 0.02238 R 21*120 n/d n/d 19.5
The photometry is based on nearby USNO-B1.0 stars.
In addition we found a source in Legacy Survey
(https://www.legacysurvey.org) which is coincident with UVOT detection
(Dichiara et al., GCN 30960).
This is a point-like object at ~0.67 arces distance from UVOT position
and has a LS DR9 photometry
g=24.32, r=24.36, z=23.31