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GCN Circular 1000

GRB010222 - Optical observation
2001-03-02T02:16:03Z (23 years ago)
Christian Veillet at CFHT <>
The optical counterpart of GRB010222 has been observed using the
CFHT Multi Object Spectrograph in imaging mode at the Cassegrain
focus of the 3.6-m CFH Telescope on the night of Feb. 28 to March 1.

Two 10 mn images were obtained in much better conditions than
the night before (GCN #998) with a seeing of about 0.8".  There are
only a few point like sources in the vicinity of the OT. A star like
object ~11" S of the OT has been carefully measured with respect
to the two stars used in GCN #998 and has a very consistent R
magnitude on the MOS exposures (R = 20.13 +/- 0.02). A fainter
object 8" from the OT is used for internal consistency checks at
R = 22.35.

Precise reduction of the images from Feb. 28 and March 1 gives the
following results:

Feb. 28.653 UTC   R = 22.73 +/- 0.10
Mar. 01.628 UTC   R = 22.96 +/- 0.10

The index of the power law decay given in GCN #998 is not 
significantly modified and found as 1.25 +/- 0.06.

There is not structure found on the OT, which is still seen as a 
point source on the March 1 combined image.

More information (with the new images of the OT) can be found at

M. Pakull, L. Mirioni, and J. McDonald are acknowledged for their
help  in this observation.

This message may be cited.
Dr. Christian Veillet,       CFHT Senior Resident Astronomer
Phone: (808) 885-3161
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