[vsnet-grb-info 8422] GRB 090926A: Swift/UVOT detection of an optical afterglow

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9938
SUBJECT: GRB 090926A: Swift/UVOT detection of an optical afterglow
DATE:    09/09/27 02:10:34 GMT
FROM:    Caryl Gronwall at PSU/Swift-UVOT  <caryl at astro.psu.edu>

C. Gronwall (PSU) and L. Vetere (PSU) report on behalf of the
Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 090926A
approximately 13 hours after the Fermi/GBM trigger (Bissaldi,
GCN Circ. 9933).  In a 357 sec observation in the white filter, we
find a candidate optical afterglow within the XRT error circle (Vetere
et al., GCN Circ. 9936) at
  RA(J2000) =  23:33:36.037 = 353.400154
  Dec(J2000) = -66:19:26.64 = 66.324067
with a 90%-confidence error radius of about 0.11 arc sec. This position
is 0.99 arc sec. from the center of the XRT error circle and is  
consistent
with the optical afterglow position found by Skynet/PROMPT (Haislip et
al., GCN Circ. 9937).  The estimated magnitude is 18.78 +/- 0.04.
This value is not corrected for the Galactic extinction due to the
reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).