TITLE: GCN CIRCULAR NUMBER: 7470 SUBJECT: GRB 080319B: ROTSE-III Observations of Optical Counterpart DATE: 08/03/20 01:07:48 GMT FROM: Heather Swan at U.of Michigan/ROTSE H. Swan (U Mich), F. Yuan (U Mich), W. Rujopakarn (Steward) ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 080319B (Swift trigger 306757; Racusin et al., GCN 7427) and began imaging at 06:13:11.06 UT (5.3 sec after the GCN notice time) under suboptimal conditions, because of condensation present on the CCD. Observations continued until about 5 hours after the trigger. This condensation made the analysis very difficult, but we detect the OT first reported in GCN 7428. Further analysis is ongoing. These unfiltered images are calibrated to the USNO B1.0 R2 catalog. start UT end UT mag mlim(of image) 06:13:11.06 06:13:16.06 5.35 9.8 06:14:30.66 06:14:50.66 8.49 13.0