[vsnet-grb-info 5089] GRB 070917: KAIT optical limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6795
SUBJECT: GRB 070917: KAIT optical limits
DATE:    07/09/17 23:05:15 GMT
FROM:    Weidong Li at UC Berkeley KAIT/LOSS  <weidong at astron.berkeley.edu>

W. Li, 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 070917 detected with Swift
(Trigger 291292; Cummings et al. GCN 6791, Tueller et al. GCN 
6792). The automatic sequence started at 07:34:52, 56 s after
the burst. The BAT location has been monitored in V, I, and
clear filters, with varying exposure times. Our image processing
pipeline did not find any new objects within the BAT error circle,
with the following photometry limits (calibrated with USNO B1.0).
These magnitudes have not been corrected for Galactic extinction
(E(B - V) = 0.45 mag; Misra et al. GCN 6793).  

======================================================================

Start UT   t(GRB)   Filter    Exp(s)  3sigma-limit      

07:34:52     56s    clear      5.0      16.8 
07:34:58     62s    clear      5.0      16.7 
07:35:04     68s    clear      5.0      16.8 
07:35:10     74s    clear      5.0      16.7 
07:35:17     81s    clear      5.0      16.9 
07:35:48    112s    V         20.0      16.2
07:36:19    143s    I         20.0      17.3
07:36:49    173s    clear     20.0      17.9
========================================================================

More images, mostly 20 s exposures in the I and clear filters,
have been obtained. No obvious OA was found in the BAT error
circle to a limiting magnitude of 16.9 - 18.0 mag, at 
t= 204 s to 2204 s after the burst. 

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