TITLE: GCN CIRCULAR NUMBER: 11462 SUBJECT: GRB 101219A: ROTSE-III Optical Limits DATE: 10/12/19 03:05:57 GMT FROM: Shashi Bhushan Pandey at ROTSE S. B. Pandey (U Mich), W. Zheng (U Mich) and W. Rujopakarn (Steward), report on behalf of the ROTSE collaboration: ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to GRB 101219A (Swift trigger 440606; Gelbord J. M., GCN 11461), producing images beginning 8.1 s after the GCN notice time. An automated response took the first image at 02:31:48.0 UT, 12.0 s after the burst, under fair conditions. We took 10 5-sec, 10 20-sec and 10 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 15.7-17.2; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 02:31:48.0 02:31:53.0 5 15.7 12.0 N 02:31:48.0 02:33:04.1 76 17.2 90.0 Y