TITLE: GCN CIRCULAR NUMBER: 30714 SUBJECT: GRB 210822A: TSHAO continued optical observation DATE: 21/08/25 16:34:52 GMT FROM: Alexei Pozanenko at IKI, Moscow apozanen@iki.rssi.ru
S. Belkin (IKI), A. Kusakin (FAP), I. Reva (FAP), Pozanenko (IKI), N. Pankov (HSE), V. Kim (FAP) report on behalf of GRB-IKI-FuN:
We continue observations of GRB 210822A (Page et al., GCN 30677; Wang et al., GCN 30678; Prasad et al., GCN 30693; Frederiks et al., GCN 30694) with Zeiss-1000 telescope of Tien Shan Astronomical Observatory. on Aug. 22 (UT) 15:48:55 -- 18:48:47. We obtained series in R-filter starting on 2021-08-24 (UT) 16:47:35.
The optical afterglow (Page et al., GCN 30677; Zheng et al., GCN 30679; Butler et al., GCN 30680; Fu et al., GCN 30684; Zhu et al., GCN 30692; Romanov et al., GCN 30701; Guelbenzu et al., GCN 30703; Siegel et al., GCN 30710; Belkin et al., GCN 30712) at the redshift of z = 1.736 (Zhu et al., GCN 30692) is detected in stacked image. Preliminary photometry of the afterglow in a stacked image is following.
Date UT start t-T0 Filter Exp. OT Err. UL(3 sigma) (mid, days) (s)
2021-08-24 16:47:35 2.33041 R 3180 21.60 0.26 22.0
The photometry is based on nearby USNO-B1.0 stars.
USNO-B1.0 RA Dec R2 20:18:06.64416 +05:17:24.1404 12.33 20:17:59.55288 +05:18:19.5912 13.05