[vsnet-grb-info 10400] GRB 110328A / Swift J164449.3+573451: optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11837
SUBJECT: GRB 110328A / Swift J164449.3+573451: optical observations
DATE:    11/03/30 01:45:38 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

A. Volnova (SAI MSU), A. Pozanenko (IKI), E. Elunko (ISTP) on behalf of 
larger GRB follow up collaboration report:

We observed the field of GRB 110328A / Swift J164449.3+573451 (Cummings et 
al. GCN 11823) with AZT-33IK telescope of Sayan observatory (Mondy) starting 
on March 28 (UT) 13:46:35, i.e. 6 minutes after second trigger (Barthelmy et 
al. GCNC 11824).
We identified the optical counterpart (Cenko et al. GCN 11827, Leloudas et 
al. GCN 11830) in the combined image of a total exposure of 67 min. The 
photometry of the optical counterpart in the combined image is R=21.50 +/- 
0.10 and based on the USNO-A2.0 star 1425-08596694 assuming R=16.6. The 
photometry is still preliminary and calibration of  field stars is necessary 
(Cenko et al. GCN 11827) to confirm the variable nature of the optical 
counterpart.