TITLE:   GCN CIRCULAR
NUMBER:  7146
SUBJECT: GRB071020: optical observations
DATE:    07/12/11 22:46:19 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the optical afterglow (Schaefer et al. GCN 6948) of  GRB071020
(Tueller et al. GCN 6954)  in I and B bands on Oct.10-11 between (UT)
23:51:34 - 01:11:47  with AZT-8 telescope of CrAO. We detected the afterglow
in I-band, and not detected it in B-band. Based on  SDSS stars (Cool  et al.
GCN 6950) RA=119.66618,  Dec=32.84706; RA=119.68899,  Dec=32.84803;
RA=119.66782, Dec=32.85465  we estimated brightness of  the optical
afterglow on a stacked images:

T0+,       Exposure,     Filter,    mag.,           UL
(mid time)

0.730 d    12x90 s        I         20.5  +/-0.3     20.5
0.728 d   12x180 s      B               n/d            21.0

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