TITLE: GCN CIRCULAR NUMBER: 6106 SUBJECT: GRB 070219: ROTSE-III Optical Limits DATE: 07/02/19 02:33:38 GMT FROM: Heather Swan at U.of Michigan/ROTSE H. Swan (U Mich), J. Aretakis (U Mich) report on behalf of the ROTSE collaboration: ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 070219 (Swift trigger 261132), producing images beginning 35 minutes after the GCN notice time. An automated response took the first image at 01:44:52.6 UT, 2076.5 s after the burst, under twilight conditions. We took 10 5-sec, 10 20-sec and 6 60-sec eposures. 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, for both single images and coadding into sets of 10. Individual images have limiting magnitudes ranging from 15.8-17.0; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 01:44:52.6 01:45:52.6 60 16.4 2076.5 N 02:13:52.6 02:14:52.6 60 17.0 3816.5 N 01:51:50.6 02:03:17.4 686 17.8 2494.5 Y