TITLE: GCN CIRCULAR NUMBER: 11142 SUBJECT: GRB 100823A - second epoch WHT observations DATE: 10/08/24 12:16:50 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), C. Copperwheat (U. Warwick) report for a larger collaboration: We obtained a second epoch of observations of GRB 100823A (Mangano et al. GCN 11135) with the WHT, beginning at 05:38 UT, approximately 5 hours after our first epoch of observations (Levan et al. GCN 11138), and 12 hours after the GRB. In our images we detect both sources A and B, both of which are constant within the photometric errors. Additionally, we have inspected archival images of the field obtained with the UKIRT Wide Field Camera (WFCAM) in November 2008 in the YJHK bands. Object B is faintly detected in all bands, while object A is below the detection limit of the shallow observations. Given the location of object B well outside the refined XRT error circle (Goad et al. GCN 11136) these results imply that it is not related to GRB 100823A, confirming the conclusion of D'Avanzo et al. (GCN 11141). We cannot rule out a faint contribution of afterglow to object A, but it non-variability in our observations, coupled with its detection in DSS2 suggest that it is not afterglow dominated."