TITLE: GCN CIRCULAR NUMBER: 11846 SUBJECT: GRB 110328A / Swift J164449.3+573451: Gemini and UKIRT IR observations DATE: 11/03/30 21:38:38 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), A. Morgan, J. Bloom, S.B. Cenko (U.C. Berkeley) report for a larger collaboration: "We obtained IR observations of GRB 110328A using both UKIRT/WFCAM and Gemini-N/NIRI on 30 March 2011, beginning at ~13:00 UT. Observations were obtained in J and H with UKIRT and in K with NIRI. The source is detected in all filters, and confirms the very red colour of the counterpart suggested by Morgan et al (GCN 11845). Comparison of these images with those taken with PAIRITEL provides maginal evidence for brightening between the PAIRITEL observations and those obtained with UKIRT and Gemini. Formally Delta_K = 0.52 +/- 0.21 and Delta_H = 0.73 +/- 0.35 mag. However, we caution that the difference between instruments, coupled with slightly different filter responses, may impact these results, and hence at present we cannot establish variability with high confidence. Further observations are planned"