TITLE:   GCN CIRCULAR
NUMBER:  11077
SUBJECT: GRB 100805A: optical observation in CrAO
DATE:    10/08/09 11:35:24 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field of the Swift GRB 100805A  (Hoversten et al., GCN 
11047) with Shajn telescope of CrAO in filter R between (UT) July, 07 
18:57:40 - 20:10:19 under good weather conditions and mean seeing of about 
1.7". Within enhanced Swift-XRT position (Goad et al., GCN 11053) we do not 
detect the afterglow   (Cenko, GCN 11050). However we detect the object in 
coordinates  (J2000) RA:  19 59 30.11 Dec: +52 37 37.79. The object is 5.6" 
away from the center of enhanced XRT position (Goad et al., GCN 11053) and 
about 4.5" from afterglow position (Cenko, GCN 11050; Holland et al, GCN 
11062). The object could be a host galaxy of  GRB 100805A.


The photometry is based on USNO-B1.0 star 1426-0390273 (J2000) RA= 19 59 
29.55 +52 37 19.6  Dec= +52 37 19.6 and assuming  R=17.59  is following:

T0+      Filter,   Exposure, Obj. mag.,  Upper Limit
(mid, d)              (s)

2.6401  R       68x60     22.5  +/- 0.1             24.0

The combined images can be found 
http://grb.rssi.ru/GRB100805A/GRB100805a_100807_R_ZTSh.gif

Our observation and photometry is in some contradiction with observation 
reported in GCN 11076 (Moskvitin et al.)