GCN Circular 9312
Subject
GRB 090426: optical observations
Event
Date
2009-04-30T23:36:12Z (17 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Rumyantsev, K. Antoniuk (CrAO), A. Pozanenko (IKI) report on behalf of
larger GRB follow-up collaboration:
We observed the afterglow (Cummings et al. GCN 9254, Xin et al., GCN 9255)
of the Swift GRB 090426 (Swift trigger 350479, Cummings et al. GCN 9254) in
R and B filters on Apr. 26 between (UT) 18:03:06 -- 19:47:38 with AZT-11
telescope of CrAO. We detect the afterglow in stacked image in R.
Astrometry of the afterglow is RA(J2000): 12 36 18.10 Dec(J2000): +32 59
08.77 with uncertainty of 0.5 arcsec is compatible with reported in GCN
9265 (Oates et al).
Preliminary photometry of combined images is based on USNO-B1.0
1230-0248707 star RA=12:36:18.03 Dec=+33:00:02.2 is following:
T0+ Filter, Exposure, mag., err.
(d) (s)
0.2342 R 15x180 21.3 +/-0.2
The combined image can de found at
http://grb.rssi.ru/GRB090426/GRB090426_AZT-11_R.gif
Taking together early observations (Yoshida et al, GCN 9266, Kinugasa et al,
GCN 9292, Mao et al, GCN 9285) with our photometry we estimate power law
decay index as ~0.9 which is compatible with decay index estimated by
Olivares et al (GCN 9268).