[vsnet-grb-info 28110] GRB 210610B: CrAO/ZTSH optical observations (correction to the GCN circ. 30212)

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30213
SUBJECT: GRB 210610B: CrAO/ZTSH optical observations (correction to the GCN circ. 30212)
DATE:    21/06/11 21:35:58 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

N. Pankov (IKI, HSE), A. Pozanenko (IKI), V. Rumyantsev (CrAO),  S. 
Belkin (IKI, HSE)  report on behalf of IKI GRB FuN:

In the GCN circ. 30212 we we incorrectly reported GRB 210610A instead of 
GRB 210610B. The circular should be read as follows.

We observed the GRB 210610B (Page  et al., GCN 30170) with ZTSH 2.6m 
telescope of CrAO observatory starting on June 11 (UT) 19:46:53.  The 
optical afterglow  first reported by UVOT (Page  et al., GCN 30170) is 
clearly detected in each of a single image of 120 exposure in R filter.
Preliminary photometry of the afterglow in the first image is following

Date       UT start   t-T0    Filter Exp.    OT      err
                      (mid, days)       (s)

2021-06-11 19:46:53   0.99683 R      1*120   19.50   0.12

The photometry is based on nearby USNO-B1.0 (R2) stars
USNO-B1.0 id
USNO_B10-1043-00282648
USNO_B10-1043-00282621