TITLE: GCN CIRCULAR NUMBER: 8995 SUBJECT: GRB 090313 - PAIRITEL NIR detections DATE: 09/03/14 06:35:06 GMT FROM: Adam Morgan at PSU/Swift-UVOT A. N. Morgan, J. S. Bloom, D. A. Perley (UC Berkeley), and D. Starr (UCB, LCOGT) report: We observed the optical afterglow of GRB 090313 (Mao et al. 2009, GCN 8980) with PAIRITEL beginning at 2009-03-13 09:39 UT, 31 minutes after the Swift Trigger. We detect the afterglow (Chornock et al., GCN 8979) in all 111 47-second mosaics of 7.8 second simultaneous exposures in the J, H, and Ks taken throughout the night. Preliminary lightcurves indicate a shallowing of the temporal decay rate during the 3.5 hours over which the afterglow was observed. The preliminary photometry yields: post_burst t_mid (hr) exp(s) filt mag merr 0.941 1883 J 14.7 0.1 0.941 1883 H 13.8 0.1 0.941 1883 K 12.8 0.1 2.302 2331 J 15.6 0.1 2.302 2331 H 14.6 0.1 2.302 2331 K 13.8 0.1 3.512 1860 J 15.9 0.1 3.512 1860 H 15.4 0.1 3.512 1860 K 14.1 0.1 No correction for Galactic extinction has been made to the above reported values. Further observations are being taken tonight.