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GCN Circular 367

Subject
GRB990704
Date
1999-07-05T21:06:17Z (25 years ago)
From
Fredrick J. Vrba at USNO <fjv@nofs.navy.mil>
The U.S. Naval Observatory GRB team (F.J. Vrba, A.A. Henden, C.B.
Luginbuhl, B. Canzian, S.E. Levine), D.H. Hartmann (Clemson Univ.) and, 
M.C. Jennings (IGPP, UCR visitor) reports:

The object reported as a possible optical counterpart to GRB 990704
by Maury et al. (GCN 363) was covered by the R-band frames we reported
in GCN 365 and also in a single 10-min V-band frame we obtained
beginning at UT 1999 July 05:00; immediately after the R-band frame
covering the area. The R- and V-band frames go to similar depths. While 
the object is easily detected in our R-band frame, it is barely seen in 
the V-band image. Thus, the object is either fairly red or was fading 
quickly. If red, it is one of a number of objects in this region with
similar red colors from visual inspection. Since the GCN 365 observations 
were unfiltered this could explain why the object was not seen on the DSS.
We also note that the object is outside the error circle of the new
X-ray source reported by Gandolfi et al. (GCN 364). While these facts
do not rule out the GCN 363 source as a possible counterpart, it should
probably be given lower priority than observations concentrating on the
GCN 364 X-ray position.
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