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GCN Circular 598

GRB000301c - R photometry and nearby faint source confirmation
2000-03-07T22:57:59Z (24 years ago)
Christian Veillet at CFHT <>
The candidate for the optical transient (OT) associated with the gamma ray burst
GRB000301c has been observed in imaging mode with MOS 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 = 21.70 +/- 0.07   2000 March 7.65 (UTC)

This value does not fit very well with the the R magnitudes published in the 
previous GCN, in particular by Mohan(595), if we assume a power law common
to all observations. In fact, the best fit of the data published so far is 
obtained  with a linear magnitude decay of 0.32 +/- 0.02 mg/day... 
The acceleration in the decay in K (GCN596) seems also to be seen in R.
More data, as well as a careful reanalysis of the existing images, are 
clearly needed!

The faint source found on March 5 (GCN592), recognized in GCN594 as identical 
to the one detected in IR at NASA IRTF, is definitely there also 
on the March 7 image. A composite of the two images is available at .
Its R magnitude is measured as 24.3 +/- 0.3 , to be refined with further 

S. Lilly is acknowledged for his help in this observation.

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