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GCN Circular 9312

GRB 090426: optical observations
2009-04-30T23:36:12Z (15 years ago)
Alexei Pozanenko at IKI, Moscow <>
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

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).
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