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GCN Circular 10706

GRB 100420A: Gemini discovery of infrared afterglow
2010-04-29T22:01:47Z (14 years ago)
Andrew Levan at U.of Leicester <>
A.J. Levan (U. Warwick), A. Cucchiara  (PSU), N.R. Tanvir (U.
Leicester), D. Fox (PSU) report on behalf of a larger collaboration:

"We obtained two epochs of observations of GRB 100420A (Baumgartner
et al. GCN 10628) using Gemini-North/NIRI. Our first epoch consisted
of 540s of observations in each of YJH and K and began at April 20
13:24 UT, approximately 8.2 hours after the burst. Our second epoch
was obtained at April 22 14:27 ~57 hours after the burst.

Within the refined XRT error circle we find a single object in our
first epoch K-band observation. The object has a location of

RA(J2000) 19:44:30.57
Dec(J2000) 55:46:10.0

with an error of 0.3" in each axis. It has a magnitude of K~21 in
our first epoch observation, but has faded below our 3-sigma detection
limit of K~22 in the second epoch. We therefore identify this source
as the infrared afterglow of GRB 100420A.

The source is not significantly detected in our J or H-band observations 
to preliminary limiting magnitudes of H>21.5, J>22.5 (3 sigma). However, 
because of the relative faintness of the K-band observations these limits
are not constraining in terms of high-z and dust extinguished
afterglow models"
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