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GCN Circular 253

GRB19990123 observations
1999-02-08T17:31:10Z (25 years ago)
Christian Veillet at CFHT <>
Christian Veillet reports: 

The optical transient (OT) associated with the gamma ray burst
GRB990123 has been observed with the new wide field camera CFH12k
at the prime focus of the 3.6-m CFH Telescope for three consecutive
nights on 1999 Feb 5.6, 6.6 and 7.6 by C. Veillet in the course
of the French GRB follow-up program at CFHT (M. Boer, CESR, C. Veillet, CFHT). 

A composite image of the field around the OT has been made
from eighteen 10min exposures (six per night).  Using the standards
published by Nilakshi et al. (GCN 252), the mean R magnitude
of the OT averages to R = 23.45 (0.1) on 1999 Feb 6.6. 
Images of the field, with a detection limit of R=25.0 (3 sigma),
can be seen at the Web site
No object is detected in a radius of 5" centered on the OT. 
This message may be cited.
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