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GCN Circular 9332

GRB 090510: Swift/UVOT Detection of a Candidate Optical Afterglow
2009-05-10T01:26:57Z (15 years ago)
Frank Marshall at GSFC <>
F. E. Marshall (GSFC) and E. A. Hoversten (PSU) report on behalf of the
Swift team:

UVOT took a second finding chart exposure of 250 seconds with the U filter starting
309 seconds after the BAT trigger for GRB 090510 (Hoversten et al.
GCN Circ. 9331). There is a candidate afterglow in the
rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	22:14:12.54 = 333.55227
  DEC(J2000) = -26:34:58.4  = -26.58290
with a 90%-confidence error radius of about 0.69 arc sec. This position is 0.7
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.95 with a 1-sigma error of about 0.17. No information about
variability is available at this time. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.02.
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