TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  2748
SUBJECT: GRB040924: KAIT observations
DATE:    04/09/25 18:08:29 GMT
FROM:    Weidong Li at UC Berkeley KAIT/LOSS  <weidong@astron.berkeley.edu>

W. Li, A. V. Filippenko, R. Chornock, and S. Jha (University of 
California, Berkeley) report:

"The Katzman Automatic Imaging Telescope (KAIT; see Li et al. 2003, 
PASP, 115, 844) at Lick Observatory robotically observed GRB 040924
(HETE Trigger #3564). Three batches of observations (a total of 34 
images) were taken during the first 100 minutes after the burst. Our 
first exposure began at 11:52:55 UT, only 44 seconds after burst. 
Unfortunately, owing to the relatively small field of view of KAIT 
(6.7' x 6.7'), the OT reported by Fox and Moon (GCN 2734) was slightly
outside our field of view in this image and in most of the subsequent
images. The OT was detected only in two sets of images taken during 
our 2 x 2 mosaic procedure. From a 120 s unfiltered exposure that 
started at 12:18:21 UT, we measured a magnitude of 18.3 (USNO-A2.0 
red mag calibrations) for the OT.  The object declined to mag 19.2 
in a 120 s image that started at 12:55:21 UT.  Referenced to the 
time of the burst, this corresponds to a decay with power-law index
alpha approximately equal to -1.0.

We also obtained six 300 s KAIT unfiltered images (with the mean 
epoch at 8:50 UT) of GRB 040924 on Sep 25 UT.  We did not detect 
the OT in the combined image, which has a 3-sigma limit of about 
mag 22.5."