[vsnet-grb-info 8214] GRB 090726: optical observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9741
SUBJECT: GRB 090726: optical observation
DATE:    09/07/31 20:36:03 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

A. Volnova (SAI MSU),  E. Pavlenko, A. Sklyanov, O. Antoniuk (CrAO), A. 
Pozanenko (IKI)  report on behalf of larger GRB follow-up collaboration:

We observed the field of  the Swift GRB 090726 (Page et al., GCN 9706)    in 
R-filter on Jul. 27 between  (UT) 18:19:22 - 20:28:58  with Shajn telescope 
of  CrAO. We  detect afterglow (Moskvitin et al., GCN  9709)  in a stacked 
image. The photometry against nearby USNO-B1.0 stars is following:

T0+     Filter, Exposure, mag.,     err.
(d)                (s)

0.8626  R     114x60     23.60 +/- 0.25

While the index of power law approximation  of  the light curve during early 
observation  (Moskvitin et al., GCN  9709) is ~ -1.0, the power law index 
between observation  presented by Moskvitin et al. (GCN  9709) and our 
observation is -1.6, clearly suggesting a break between 0.079 and 0.863 
days.