TITLE: GCN CIRCULAR NUMBER: 11103 SUBJECT: GRB 100816A: ROTSE-III Optical Limits DATE: 10/08/16 01:42:21 GMT FROM: Shashi Bhushan Pandey at ROTSE S. B. Pandey (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 100816A, possibly a short duration burst, (Swift trigger 431764; Oates, S. R., GCN 11102), producing images beginning 6.8 s after the GCN notice time. An automated response took the first image at 01:00:05.7 UT, 1334.3 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. Individual images have limiting magnitudes ranging from 16.2-17.9; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 01:00:05.8 01:00:10.8 5 16.6 1334.4 N 01:01:37.27 01:05:58.67 180 18.5 1534.4 Y