TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3327 SUBJECT: GRB 050502: Confirmed variability of the afterglow candidate + DATE: 05/05/02 07:11:15 GMT FROM: Josh Bloom at Harvard/CFA C. Blake (Harvard) and J. S. Bloom (UCB) report: PAIRITEL has continued to image the Yost et al. optical candidate afterglow (GCN #3322). We confirm that the IR source (#3326) initially faded, strongly confirming the hypothesis from Yost et al. In particular, from T+47min to T+94 min the source faded by ~1.1 mag in J. But from T+94 min to T+121 min, there is some evidence for brightening by ~0.1 mag in J-band. A similar result is found in H and Ks. Based on an astrometric tie of 2MASS to a 141 sec J-band image from (start) 2005-05-02 02:52:40 UT, we find IRT: RA = 13:29:46.33, Dec = 42:40:27.3 --Offset to IRT-- A : RA = 13:29:42.78, Dec = 42:40:49.2 21.83" S, 39.19" E B: RA = 13:29:44.23, Dec = 42:38:13.1 134.20" N, 23.21" E The uncertainty in the absolute WCS is ~0.5 arcsec. Sources A and B are nearby bright sources suitable for blind offset spectroscopy."