TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  2729
SUBJECT: TAROT Observations of GRB 040916 (HETE #3558) 
DATE:    04/09/21 08:24:52 GMT
FROM:    Jean-Luc Atteia at Lab d Astrophys.,OMP,Toulouse  <atteia@ast.obs-mip.fr>

TAROT Observations of GRB 040916 (HETE #3558)

Klotz, A., Atteia, J.L., G. Stratta, and Boer M. report:

TAROT observed the HETE Ground alert #3558
from 2004 Sept. 16 02:26:59 UT
  to 2004 Sept. 16 02:57:35 UT,
as a series of 30-s unfiltered images
in the field described by Yamazaki et al.
(GCN Circ. 2712, 2713).

We first computed the medians of sub-series
of 3 images to eliminate cosmics, which were
then co added to obtain a single image.

Comparing to the USNO-1B catalog and DSS
image, we are able to detect all stars
brighter than R=19.4, and very few
stars fainter than R=20.0.

The candidate proposed Kosugi et al.
(GCN 2726) is not detected at the 3
sigma level. We conclude that the
afterglow had a magnitude R > 19.4
in a time period extending from 2.39 to 2.89 hours
after the GRB.

We note that a fuzzy patch is seen at
mag R=19.5 in the image at the position of
the afterglow, which we do not
consider as the afterglow, but as a background
fluctuation.

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