GCN Circular 611
Subject
GRB000301C - B and R photometry
Date
2000-03-14T23:57:10Z (24 years ago)
From
Christian Veillet at CFHT <veillet@cfht.hawaii.edu>
The candidate for the optical transient (OT) associated with the gamma
ray burst GRB000301C has been observed in imaging mode with OSIS on
the 3.6-m CFH Telescope in the course of the French GRB follow-up
program at CFHT (M. Boer, CESR, C. Veillet, CFHT).
The OT has the following magnitude, using star A (GCN573) photometry
(GCN583):
R = 23.82 +/- 0.10 2000 March 14.60 (UTC)
(two 30mn exposures)
B = 24.83 +/- 0.12 2000 March 14.60 (UTC)
(one 55mn exposure)
The power-law decay described with alpha = -2.1 +/- 0.1 (GCN610) is not
sufficient to account properly for the last four measurements (GCN598,
604, 610 and this GCN), which are better fit with alpha = -2.7 +/- 0.1 .
The first phase of the decay would cover the first four days after the
burst, with alpha = -0.91 +/- 0.08. A graph with these two consecutive
power laws, as well at the new images, are at
http://www.cfht.hawaii.edu/~veillet/grb.html
As for the apparent B-R, the error bars are large enough to make it close
to the value determined using MOS on March 3.5 (0.86 +/- 0.06) or the one
published by Halpern (0.77 +/- 0.06 in GCN585 a week ago).
As the GRB is still steadily decaying, it's unlikely to have the underlying
galaxy contributing significantly to the measured flux. This galaxy should
probably be fainter than R = 24.5, confirming the comment by Fruchter et al.
(GCN602) from HST imaging data (R >~ 24).
A 20 micron camera will be installed on the telescope today for 10 nights.
No new data on this GRB will be acquired during this period.
Aloha from Hawaii!
I. Gable is acknowledged for his help in this observation.
This message may be cited.
--
************************************************************
Dr. Christian Veillet, CFHT Senior Resident Astronomer
Phone: (808) 885-3161 http://www.cfht.hawaii.edu/~veillet/
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