TITLE: GCN CIRCULAR NUMBER: 10077 SUBJECT: GRB 091024: TLS Upper Limit DATE: 09/10/25 05:59:03 GMT FROM: Alexander Kann at TLS Tautenburg D. A. Kann, and U. Laux (TLS Tautenburg) report: We observed the afterglow of the ultra-long Swift/GBM GRB 091024 (Marshall et al., GCN 10062, Mundell et al., GCN 10063, Bissaldi & Connaughton, GCN 10070) with the 1.34m Schmidt telescope of the Thueringer Landessternwarte Tautenburg, Germany, 0.6 days after the GRB. We obtained 6 x 600 sec images in Rc. As a comparison star, we use the USNOB1.0 star at: RA (J2000) = 22:37:31.11 Dec. (J2000) = +56:59:26.23 which has R2 = 17.78 mag. This was one of the rare non-blended stars that was bright enough to be detected in the catalog. At the afterglow position, we do not detect any source which is not detected anyway in the DSS2 red plate. We place the following 2 sigma upper limit on the afterglow: dt Filter UL ____________________________________ 0.602309 Rc 21.0 and note that the true upper limit may be less deep due to crowding (the afterglow pretty much conincides with a ~20th mag object detected in the DSS). No further observations are planned. This message may be cited.