TITLE: GCN CIRCULAR NUMBER: 8436 SUBJECT: GRB 081029: ROTSE-III Detection of Optical Counterpart DATE: 08/10/29 01:57:59 GMT FROM: Eli Rykoff at UCSB E.S. Rykoff (UCSB), report on behalf of the ROTSE collaboration: ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to GRB 081029 (Swift trigger 332931, GCN 8435, Sakamoto et al.). The first image was at 01:45:22.8 UT, 86.0 s after the burst (8.8 s after the GCN notice time). The unfiltered images are calibrated relative to USNO A2.0. We detect a 16.5 magnitude, fading source with coordinates: 23:07:05.36 -68:09:19.74 (J2000), with positional uncertainty of 1" or better start UT mag mlim(of image) ---------------------------------- 01:45:22.8 16.5 17.8 This source is not visible in DSS (second epoch), 2MASS or the MPChecker database. A jpeg image is available at http://www.rotse.net/images/gsb332931_3c011-020_key.jpg Note that the object marked 36 is the candidate in question. Continuing observations are in progress.