[vsnet-grb-info 10597] GRB 110520A: WHT IR observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12026
SUBJECT: GRB 110520A: WHT IR observations
DATE:    11/05/21 01:50:43 GMT
FROM:    Andrew Levan at U.of Leicester  <A.J.Levan at warwick.ac.uk>

A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), R. Canning (U.
Cambridge), F. Riddick (ING) report on behalf of a larger collaboration:

"We observed the location of GRB 110520A (GCN 12020) using the William
Herschel Telescope equipped with LIRIS. Observations began at 22:21
UT on 20 May 2011, 1.9 hours after the burst, and were conducted
in the zYJHK bands. We do not find any sources with the XRT
localization of GRB 110520A, down to preliminary limiting magnitudes
of z>22.1, J>20.8, H>20.1, K>19.5, calibrated against SDSS and 2MASS
observations of the field.

We do note two sources which lie just outside the XRT localization.
The object noted by Schulze et al. (GCN 12025) is very weakly
detected in our images, while an additional object at

RA(J2000) 08:57:22.02 
DEC(J2000) 56:25:35.31 
+/- 0.2"

is also present in all our observed bands, but is offset ~4" from
the XRT location.  At this stage we cannot ascertain if either of
these sources is a plausible afterglow for GRB 110520A."