[vsnet-grb-info 5292] GRB071021: Optical+NIR observations
GCN Circulars
gcncirc at capella.gsfc.nasa.gov
Wed Oct 24 04:55:27 JST 2007
TITLE: GCN CIRCULAR
NUMBER: 6983
SUBJECT: GRB071021: Optical+NIR observations
DATE: 07/10/23 19:55:21 GMT
FROM: Paul Price at IfA,UH <price at ifa.hawaii.edu>
P.A. Price (IfA, Hawaii), T. Minezaki (IoA, Tokyo), L. Cowie (IfA,
Hawaii), Y. Yoshii (IoA, Tokyo) and Y. Kakazu (IfA, Hawaii) report:
We observed the candidate optical afterglow of GRB071021 (GCN##6968,
6971,6972) with the robotic MAGNUM telescope + MIPS dual-beam imager.
Some observations were significantly affected by cloud, but images in I,
H and K were obtained through thin clouds. We do not detect any source
in our images at the candidate afterglow position, to the following 3
sigma limits, derived from the USNO-1B and 2MASS catalogues:
Filter midtime(UTC) Exp. time upper limits
I 2007-10-22 6.9h 67min >22.5mag
H 2007-10-22 7.7h 30min >20.4mag
K 2007-10-22 6.1h 33min >19.8mag
Our K-band upper limit is consistent with the detection of the afterglow
in K band reported by Kawai et al. (GCN 6976; K~21 mag at 2007-10-22
05:38 UTC).
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