TITLE: GCN CIRCULAR NUMBER: 8730 SUBJECT: GRB 081226: ROTSE-III Optical Limits DATE: 08/12/26 01:32:34 GMT FROM: Brad Schaefer at LSU B. E. Schaefer (Louisiana State), E.S. Rykoff (UCSB), F. Yuan (U Mich), report on behalf of the ROTSE collaboration: ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to GRB 081226 (Swift trigger 338177; Godet, GCN 8729), producing images beginning 8.8 s after the GCN notice time. An automated response took the first image at 01:04:02.8 UT, 25.4 s after the burst, under excellent conditions. We took 10 5-sec, 20 20-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 or the XRT error circle, for both single images and coadding into sets of 10; the field is not crowded. Individual images have limiting magnitudes ranging from 16.8-17.4; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 01:04:02.8 01:04:07.8 5 17.0 25.4 N 01:04:02.9 01:05:19.0 76 17.8 25.5 Y