GCN Circular 9938

Subject

GRB 090926A: Swift/UVOT detection of an optical afterglow

Event

Date

2009-09-27T02:10:34Z (17 years ago)

From

Caryl Gronwall at PSU/Swift-UVOT <caryl@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. 9933Loading...
 
 ).  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. 9936Loading...
 
 ) 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. 9937Loading...
 
 ).  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).