TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5041 SUBJECT: GRB 060501: ROTSE-III Optical Limits DATE: 06/05/01 09:19:00 GMT FROM: Eli Rykoff at U of Michigan/ROTSE E.S. Rykoff (U Mich), B. E. Schaefer (Louisiana State), S.A. Yost (U Mich), R. Quimby (U Texas), report on behalf of the ROTSE collaboration: ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 060501 (Swift trigger 208050, GCN 5040), producing usable images beginning 92 s after the GCN notice time. An automated response took the first image at 08:22:4.6 UT, 426 s after the burst, under fair conditions with high airmass. We took 7 20-s exposures before bad weather forced the system to close. These unfiltered images are calibrated relative to USNO A2.0 (R). Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma error circle. Individual images have limiting magnitudes ranging from 16.3-16.4; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 08:22:04.6 08:22:24.6 20 16.4 426 N 08:22:04.6 08:25:29.4 140 17.4 426 Y