[vsnet-grb-info 3811] GRB 060926: Swift-UVOT UVW1 Detection Retraction

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5645
SUBJECT: GRB 060926: Swift-UVOT UVW1 Detection Retraction
DATE:    06/09/28 14:57:57 GMT
FROM:    Pete Roming at PSU  <roming at astro.psu.edu>

P. Roming (PSU) and S. T. Holland (GSFC/USRA) report on behalf of the 
Swift-UVOT team:

Due to an error in the flux calculation, the reported UVW1 (251 nm) filter 
detection in GCN 5625 is not real. No optical afterglow is detected at the 
3-sigma level in individual or coadded exposures in this filter. The 
3-sigma limiting magnitude for the coadded images is listed below:

Filter      T_range(s)      Exp(s)     Upper Limit (3-sigma)
UVW1    487-11748      1337       20.4

where T_range is the start and end times of the coadded exposures. No 
correction has been made for Galactic reddening along the line of sight 
(E(B-V) = 0.16). We also point out that the 4.8-sigma level V-filter 
detection report in GCN 5625 is real. We apologize for any inconvenience 
this error has created.