TITLE: GCN CIRCULAR NUMBER: 11145 SUBJECT: GRB 100823A: Candidate IR afterglow DATE: 10/08/24 17:13:52 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (U. Warwick), K. Wiersema, N. Tanvir (U. Leicester), C. Copperwheat (U. Warwick) report on behalf of a larger collaboration: We obtained infrared imaging of the location of GRB 100823A ( using LIRIS on the 4.2m WHT, beginning at 01:34 UT, ~8 hours after the burst. Observations were obtained in the JH and K bands, with a total exposure time of 540 s in each band. We detect sources A and B of Levan et al. (GCN), but also find a new source within the XRT error circle of Goad et al. GCN 11135, but see also, http://www.swift.ac.uk/xrt_positions/00432420/image.php with a position of, C: RA(J2000) 01:22:48.94 DEC(J2000) 05:50:05.9 The object has K=19.6 calibrated against 2MASS, and is faintly visible in the H-band, but not in the J or z, suggestive of a red colour. At the current time we cannot make statements as to the variability of the source, but its red colour, akin to extinguished GRB afterglows, coupled with a location within the XRT error circle leads us to suggest that it is the afterglow of GRB 100823A.