TITLE: GCN CIRCULAR NUMBER: 12089 SUBJECT: GRB 110625A: ROTSE-III Optical Limits DATE: 11/06/25 22:24:00 GMT FROM: Weikang Zheng at U.of Michigan W. Zheng (U Mich) and W. Rujopakarn (Steward), report on behalf of the ROTSE collaboration: ROTSE-IIId, located at the Turkish National Observatory at Bakirlitepe, Turkey, responded to GRB 110625A (Swift trigger 456073; Page et al., GCN 12088), producing images beginning 6.8 s after the GCN notice time. An automated response took the first image at 21:08:48.8 UT, 20.3 s after the burst, and during the gamma-ray emission, under fair conditions. We took 10 5-sec, 10 20-sec and 110 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 or the XRT error circle, for both single images and coadding into sets of 10. Individual images have limiting magnitudes ranging from 15.5-16.6; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 21:08:48.8 21:10:56.3 127 16.9 20.3 Y 21:11:05.2 21:15:42.8 277 17.5 156.7 Y 21:15:51.7 21:20:29.5 277 17.5 443.2 Y