TITLE: GCN CIRCULAR NUMBER: 13020 SUBJECT: GRB 120308A: PAIRITEL NIR observations DATE: 12/03/08 08:46:02 GMT FROM: Adam Morgan at U.C. Berkeley A. N. Morgan, C. R. Klein, and J. S. Bloom (UC Berkeley) report: We observed the field of GRB 120308A (Baumgartner et al., GCN 13017) with the 1.3m PAIRITEL located at Mt. Hopkins, Arizona. Observations began at 2012-Mar-08 07h14m27s UT, ~1.0 hours after the Swift Trigger, under moderate airmass (~1.7). In mosaics (effective exposure time of 0.39 hours) taken simultaneously in the J, H, and Ks filters, we detect the afterglow (Virgili et al., GCN 13018, Elenin et al., GCN 13019) at the Liverpool position (Virgili et al., GCN 13018). The preliminary photometry yields: post burst t_mid (hr) exp.(hr) filt mag m_err 1.44 0.39 J 17.71 0.21 1.44 0.39 H 16.74 0.22 1.44 0.39 Ks 16.06 0.25 Observations are ongoing. All magnitudes are given in the Vega system, calibrated to 2MASS. No correction for Galactic extinction has been made to the above reported values.