TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3723 SUBJECT: GRB 050801: ROTSE-III Detection of Possible Counterpart DATE: 05/08/01 18:34:58 GMT FROM: Eli Rykoff at U of Michigan/ROTSE E.S. Rykoff (U Mich), S.A. Yost (U Mich), W. Rujopakarn (U Mich) report on behalf of the ROTSE collaboration: ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to GRB 050801 (Swift trigger 148522). The first image was at 18:28:23.9 UT, 21.9 s after the burst (7.9 s after the GCN notice time). The unfiltered images are calibrated relative to USNO A2.0. We detect a new object, not visible in the DSS (second epoch), with coordinates: 13:36:35.4 -21:55:42.0 (J2000) start UT mag mlim(of image) ---------------------------------- 18:28:23.9 15.0 17.0 Continuing observations are in progress.