TITLE:   GCN CIRCULAR
NUMBER:  28708
SUBJECT: GRB 201020A: CrAO/ZTSH optical observations
DATE:    20/10/21 00:03:22 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the GRB 201020A  (Ambrosi et al., GCN 28696) with ZTSH 2.6m 
telescope of CrAO observatory starting on Oct. 20 (UT) 16:06:30.  The 
optical afterglow  (Ambrosi et al., GCN 28696;  Adachi et al., GCN 
28697; Fu  et al., GCN 28701;  Belkin  et al., GCN  28703) is clearly 
detected in R filter.
Preliminary photometry of the afterglow in a combined image is following

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

2018-10-20 16:06:30   0.42991 R      30*120   20.00   0.10   21.5

The photometry is based on several nearby USNO-B1.0 (R2) stars.