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GCN Circular 10783

GRB 100418A: CrAO optical observations
2010-05-19T19:25:13Z (14 years ago)
Alexei Pozanenko at IKI, Moscow <>
V. Rumyantsev (CrAO), A. Pozanenko (IKI)  report on behalf of  larger GRB 
follow-up collaboration:

We observed the field of the Swift GRB 100418A (Marshall  et al. GCN 10612) 
with Shajn telescope of  CrAO between (UT) May, 14  21:07 -- 22:48 under 
photometric weather conditions and mean seeing of about 2 arcsec.
The preliminary photometry of the afterglow+host in a stacked image based on 
USNO-B1.0 star 1014-0271368  (RA(J2000) = 17:05:26.42 Dec(J2000)= 
+11:27:32.9)  assuming  R=17.32  is following:

T0+      Filter,   Exposure,  mag.
(mid, d)              (s)

26.0332     R       90x60    21.86 +/-0.06

The photometry is compatible with R-magnitude reported by Perley et al, GCN 
10727 (R=21.85+/-0.05 at 17.739 days) and still brighter than assumed 
R-magnitude of the normal type of host galaxy (SDSS based ugriz-> R 
conversion) which cannot be explained solely by afterglow contribution 
fading steeper than power law with decay index of  .~0.8.
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