TITLE: GCN CIRCULAR NUMBER: 10324 SUBJECT: GRB 100111A: PAIRITEL NIR Upper Limits DATE: 10/01/11 22:35:56 GMT FROM: Adam Morgan at U.C. Berkeley A. N. Morgan, S. B. Cenko, J. S. Bloom, (UC Berkeley), report: We observed the field of GRB 100111A (Vetere et al., GCN 10317) with the 1.3m PAIRITEL located at Mt. Hopkins, Arizona. Observations began at 2010-01-11 12:20:11 UT, ~8.12 hours after the Swift trigger. Observations were taken under good weather conditions but at high airmass before dawn. In mosaics (effective exposure time of ~2223 seconds) taken simultaneously in the J, H, and Ks filters, we do not detect the optical afterglow (Vetere et al., GCN 10317; Xu et al., GCN 10318; Hoversten et al., GCN 10323). The preliminary photometry yields: post_burst t_mid(h) exp(s) filt U. Limit (3 sig) 8.60 2223 J > 19.0 8.60 2223 H > 18.5 8.60 2223 Ks > 18.0 All magnitudes given in the Vega system, calibrated to 2MASS. No correction for Galactic extinction has been made to the above reported values.