[vsnet-grb-info 4774] GRB 070612B: KAIT limits

[GCN Circulars]

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  <weidong at astron.berkeley.edu>

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.