[vsnet-grb-info 10869] GRB 110820A: CrAO optical upper limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12290
SUBJECT: GRB 110820A: CrAO optical upper limit
DATE:    11/08/20 22:17:57 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

V. Rumyantsev,  K. Antoniuk (CrAO), A. Pozanenko (IKI) report on behalf of 
larger GRB  follow-up collaboration:

We observed  the field of the Swift GRB 110820A (Troja  et al., GCN 12288) 
with AZT-11 telescope of CrAO between  Aug. 20 (UT) 18:23
 - 19:21. Within the XRT error box  (Troja  et al., GCN 12288)  we do not 
detect any source. The photometry is based on the USNO B1.0 star 
1602-0161058    (22:52:45.06 +70:17:17.5) assuming R=18.23:

T0+      Filter,   Exposure, OT,           Upper Limit (3 sigma)
(mid, d)              (s)

0.0520   R        20x180       n/d           21.6