GCN Circular 9539
Subject
GRB 090618: ZTSh optical observations
Event
Date
2009-06-21T01:01:06Z (16 years ago)
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 afterglow (Schady et al., GCN 9512; Cenko et al., GCN 9513;
Perley, GCN 9514; Rujopakarn et al., GCN 9515) of the Swift GRB 090618
between (UT) Jun. 18 19:51 - Jun. 19 00:51 with Shajn telescope of CrAO.
We detect afterglow in every BVRI of 60 s exposure images of the series.
Coordinates of the afterglow are RA(J2000): 19 35 58.77 Dec(J2000): +78 21
24.2 with uncertainties of 0.3 arcsec.
Preliminary photometry of selected images based on USNO-B1.0 star
1683-0077955 (RA=19 36 36.34 Dec=+78 21 07.00) assuming R=16.57 is
following:
T0+ Filter, Exposure, mag., err.
(d) (s)
0.4763 R 60 18.60 +/-0.05
0.5680 R 60 18.87 +/-0.03
0.6496 R 60 19.17 +/-0.04
0.6796 R 60 19.19 +/-0.10
The power low index of light curve approximation between 0.48 - 0.65 days
is ~ -1.6, while after 0.65 days after burst onset we observe flattening of
the light curve. A finding chart can be found at
http://grb.rssi.ru/GRB090618/GRB090618_090618_R_ZTSh.gif