[vsnet-grb-info 2301] GRB 051021: P200 Ks Observations

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4140
SUBJECT: GRB 051021: P200 Ks Observations
DATE:    05/10/22 21:41:37 GMT
FROM:    S. Bradley Cenko at Caltech  <cenko at srl.caltech.edu>

S. Bradley Cenko, Chris Conselice, Kevin Bundy, (Caltech), Derek B. Fox
(Penn State), and Edo Berger (Carnegie), report on behalf of the
Caltech-NRAO-Carnegie GRB collaboration:

"We have imaged the field of GRB 051021 (Yoshida et al., GCN 4116) with
the Wide Field Infrared Camera mounted on the Palomar 200" Hale Telescope.
Our images consisted of 9 x 120 s exposures taken in the Ks filter at a
mean epoch of approximately 22 October 5:24 UT (~ 16 hours after the
burst).  We find at best a marginal (< 3-sigma) detection at the location
of the OT (Fox et al., GCN 4120).  Our 3-sigma limiting magnitude,
calculated with respect to several 2mass stars in the field, is
approximately Ks > 19.0.

We note that under the standard afterglow model, our result is
inconsistent with the J-band detection reported by Haislip et. al (GCN
4127), and therefore calls into question the interpreration of GRB 051021
as a high redshift event."