TITLE: GCN CIRCULAR NUMBER: 819 SUBJECT: GRB000926 optical observations DATE: 00/09/29 23:42:30 GMT FROM: Fredrick J. Vrba at USNO On behalf of the USNO GRB team, F. Vrba and B. Canzian, report two additional R-band photometric measurements of the GRB 000926 optical counterpart, discovered by Gorosabel et al. (GCN 803) and Dall et al. (GCN 804). Our observations were obtained with the USNO, Flagstaff Station, 1.0-m telescope. These measurements are based on a preliminary photometric calibration from a limited number of standard stars. UT Date Magnitude Sep 28.097 R = 19.70 +/- .03 Sep 29.146 R = 21.05 +/- .04 If weather permits at a later date, we will produce a fully-calibrated UBVRI standard sequence, as we have for several earlier GRB fields.