TITLE: GCN CIRCULAR NUMBER: 5858 SUBJECT: GRB 061126: Early Detection of the IR Afterglow DATE: 06/11/26 11:44:30 GMT FROM: Josh Bloom at UC Berkeley GRB 061126: Early Detection of the IR Afterglow J. S. Bloom (UC Berkeley), on behalf of a larger collaboration, reports: "We began observing the field of GRB 061126 (GCN 5854) with the Peters Automated Infrared Imaging Telescope (PAIRITEL) starting at 2006-11-26 08:48:54.3 UTC, after an automated trigger. This is 58 seconds after the GRB trigger and 42 seconds after the BAT Position Notice was issued. In individual 7.8 sec exposures, we detect a transient source simultaneously in JHKs at position of (J2000): RA 05:46:24.475 DEC +64:12:38.46 (+- 250 mas), consistent with the position of the X-ray transient (GCN 5855) and optical transient (GCN 5866). In a stack of 39 exposures ending at 08:57:11.3 UTC, we find the preliminary magnitudes of the afterglow of: J = 14.12 +/- 0.03 H = 13.26 +/- 0.03 Ks = 12.65 +- 0.06 Imaging has continued since the trigger." A false-color composite image of the field may be found at: http://lyra.berkeley.edu/~jbloom/grb061126.ps.gz This message may be cited.