GCN Circular 12026
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."