[vsnet-grb-info 28142] GRB 210610B: CrAO/ZTSH continued optical observations and light curve

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30245
SUBJECT: GRB 210610B: CrAO/ZTSH continued optical observations and light curve
DATE:    21/06/16 22:55:29 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:

We observed the GRB 210610B (Page  et al., GCN 30170) with ZTSH 2.6m
telescope of CrAO observatory on June 10,11  (Rumyantsev et al., GCNs 
30175, 30178; Pankov et al., GCN 30213) and June 12 - 14.  The optical 
afterglow  first reported by UVOT (Page  et al., GCN 30170) is clearly 
detected in each epochs. Some preliminary photometry is following.

Date       UT start   t-T0    Filter Exp.    OT      err   UL(3 sigma)
                      (mid, days)       (s)

2021-06-12 20:54:55   2.0545  R      2*120   20.80   0.10  22.2
2021-06-12 22:41:00   2.1282  R      2*120   20.89   0.10  22.8
2021-06-14 20:40:19   4.0649  R     25*120   21.90   0.11  23.3

The photometry is based on calibrations stars reported in (Pankov et
al., GCN 30213).

Based on our observations in ZTSh on June 10-14, AbAO (Pankov et al., 
GCN 30243) and photometry reported in GCNs we report the light curve of 
the afterglow which can be found in

http://grb.rssi.ru/GRB210610B/GRB210610B_LC.png

After plateau phase lasting up to ~ 0.3 days in R-filter, the LC can be 
approximated by a single power law with index of -1.6.