TITLE: GCN CIRCULAR NUMBER: 8807 SUBJECT: GRB 090113: ROTSE-III Optical Limits DATE: 09/01/13 23:23:49 GMT FROM: Heather Swan at U.of Michigan/ROTSE H. Swan (U Mich), E.S. Rykoff (UCSB), T. Guver (U Arizona), T.A. McKay (U Mich), F. Yuan (U Mich), B. E. Schaefer (Louisiana State), R. Quimby (Caltech), report on behalf of the ROTSE collaboration: ROTSE-IIId, located at the Turkish National Observatory at Bakirlitepe, Turkey, responded to GRB 090113 (Swift trigger 339852; H. A. Krimm, GCN 8804), producing images beginning 6.4 s after the GCN notice time. An automated response took the first image at 18:49:02.4 UT, 503.2 s after the burst, under windy conditions. We took 10 5-sec, 10 20-sec and 30 60-sec exposures. These unfiltered images are calibrated relative to USNO A2.0 (R). Imaging is on going. Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma Swift/BAT error circle, for both single images and coadding into sets of 10; the field is not crowded. Individual images have limiting magnitudes ranging from 14.9-16.4; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 18:49:02.5 18:51:08.2 125 16.6 503.3 Y 18:51:16.6 18:55:52.3 275 17.3 637.4 Y 18:60:45.7 19:05:21.5 275 17.3 1206.5 Y