GCN Circular 830
Subject
GRB000926 - Optical observations
Event
Date
2000-10-04T05:10:14Z (25 years ago)
From
Christian Veillet at CFHT <veillet@cfht.hawaii.edu>
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GRB000926 - Optical observations
The optical counterpart of GRB000926 has been observed using the
CFH12K CCD mosaic camera at the prime focus of the 3.6-m CFH
Telescope for the fifth night on Oct. 3.2304 .
Following GCN #829 by Halpern et al., a more accurate reduction of the
CFHT data has been made, with the problems encountered when none of the
observations is made in photometric reduction.
A fist full reduction of the images leads to a more constant slope.
The change seen previously in the decay rate (GCN #825, #826 and #827) doesn't
seem to be real. Even if there are still discrepancies between the MDM and
CFHT data, there are now smaller, thanks to the work on the secondary reference
stars made by F. Vrba (USNO).
The 5 nights of observations at CFHT lead to a decay slope of 2.16 +/- 0.03
but it's not really possible to link accurately the CFHT magnitudes to others
as long as there is no calibration of the field stars made.
A graph of the light curve in R from CFHT observations can be found at
http://www.cfht.hawaii.edu/~veillet/grb.html
where more information on the photometric reductions can be found.
An accurate photometric calibration of stars 1 and 2 (see the image
on the web page) is definitely needed.
L. Wells, D. Woodworth and J. Luthe are acknowledged for their
help in this observation.
This message may be cited.
--
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Dr. Christian Veillet, CFHT Senior Resident Astronomer
Phone: (808) 885-3161 http://www.cfht.hawaii.edu/~veillet/
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