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GCN Circular 9329

Subject

GRB 090418A: optical observation

Date

2009-05-09T20:15:43Z (15 years ago)

From

Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

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

We observed the afterglow of  the Swift GRB 090418A (Mangano et al., GCN 
9149Not found
 
 
) in I-filter on Apr. 20 (UT) 02:34:12 - 04:08:27
and in R-filter on Apr. 20 (UT) 21:03:05 - 22:49:20 with Shajn telescope of 
CrAO. We clearly detect afterglow in both epochs in stacked images. 
Preliminary photometry  of Apr. 20 as well a photometry in V-filter of  Apr. 
18 observations (Pavlenko et al. GCN 9179Not found
 
 
) is following:

T0+     Filter, Exposure, mag.,     err.  UL Seeing
(d)             (s)

0.5476  V       17x60     22.3 +/- 0.2  23.2  1.9"
2.4507  R       70x60     22.8 +/- 0.1  24.4  1.9"

Due to worse seeing (2.4") on Apr. 20 (UT) 02:34:12 - 04:08:27 the afterglow 
is evidently contaminated with nearby galaxy and photometry will be reported 
later. The photometry of Apr. 20 (UT) 21:03:05 - 22:49:20  also should be 
treated with caution due to possible contamination.