TITLE:   GCN CIRCULAR
NUMBER:  7896
SUBJECT: GRB 080623: Swift/UVOT Non-Detection of an Optical Afterglow  
DATE:    08/06/23 11:35:42 GMT
FROM:    Stephen Holland at USRA/NASA/GSFC/SSC  <sholland@milkyway.gsfc.nasa.gov>

S. T. Holland (CRESST/USRA/GSFC) reports on behalf of the Swift/UVOT
Team:

    UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 1331 seconds after the BAT trigger. No
afterglow candidate has been found in the initial data products. The
2.7'x2.7' sub-image covers 100% of the XRT error circle (Perez, et
al., 2008, GCN Circ. 7895). The 3-sigma upper limit is 21.1 mag.  No
correction has been made for the large expected extinction
corresponding to E(B-V) of 0.35 mag.  The USNO B1.0 star 279-072176 is
located 2.07 arcsec from the centre of the XRT error circle.