[vsnet-grb-info 9221] GRB 100420A: Gemini discovery of infrared afterglow

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  10706
SUBJECT: GRB 100420A: Gemini discovery of infrared afterglow
DATE:    10/04/29 22:01:47 GMT
FROM:    Andrew Levan at U.of Leicester  <A.J.Levan at warwick.ac.uk>

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"