[vsnet-grb-info 20881] GRB 180720B : TSHAO optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22979
SUBJECT: GRB 180720B : TSHAO optical observations
DATE:    18/07/20 21:36:57 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

I. Reva (FAPHI), A. Pozanenko (IKI), A. Volnova (IKI),  E. Mazaeva (IKI), 
A. Kusakin (FAPHI),  M. Krugov (FAPHI) report on behalf of larger GRB
follow-up collaboration:

We observed the field of GRB 180720B (Siegel  et al., GCN 22973)  with 
Zeiss-1000 telescope of Tien Shan Astronomical Observatory starting on July 
20  (UT) 19:46:17. We obtained several images in R and B-filters.  The 
optical afterglow (Martone et al. GCN 22976;  Sasadaet al., GCN 22977)  is 
clearly detected in both filters.  Preliminary photometry  of the afterglow 
at  (UT, mid time) 19:59 is R =17.1 +/- 0.1. The photometry is based on 
nearby USNO-B1.0 (R2) stars.