TITLE: GCN CIRCULAR NUMBER: 6516 SUBJECT: GRB 070612B: KAIT limits DATE: 07/06/12 08:32:16 GMT FROM: Weidong Li at UC Berkeley KAIT/LOSS W. Li, R. J. Foley, D. A. Perley, J. S. Bloom, and A. V. Filippenko, University of California, Berkeley, on behalf of the KAIT GRB team, report: The robotic 0.76-m Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory observed GRB 070612B detected with Swift (Trigger 282073; Grupe et al. GCN 6511). The automatic sequence started at 06:22:01, 44 s after the burst. The BAT location and the XRT position (Grupe & Evans GCN 6514) have been monitored in V, I, and clear filters, with varying exposure times. The observations are still on-going. Our image processing pipeline did not find any new objects within the XRT error circle, with the following photometry limits (calibrated with USNO B1.0). These magnitudes have not been corrected for Galactic extinction, which as estimated by the NED extinction calculator is approximately E(B-V) = 0.838 mag in this direction. ====================================================================== Start UT t(GRB) Filter Exp(s) 3sigma-limit 06:22:01 44s clear 5.0 18.1 06:22:09 52s clear 5.0 18.2 06:22:17 60s clear 5.0 18.2 06:22:25 68s clear 5.0 18.1 06:22:34 77s clear 5.0 18.1 06:22:42 85s clear 5.0 18.1 06:23:10 113s V 15.0 17.1 06:23:36 139s I 15.0 18.0 06:24:00 163s clear 15.0 18.8 06:24:31 194s V 45.0 17.6 06:25:27 250s I 45.0 18.5 06:26:21 304 clear 45.0 19.3 ======================================================================== More images, mostly 60 s exposures in the I and clear filters, have been obtained. No obvious OA was found in the XRT error circle to a limiting magnitude of 19.0 - 19.9 mag, at t= 304s to 6642s after the burst. More analyses are in progress.