[vsnet-grb-info 3685] GRB060904b: Optical observations with Swift/UVOT

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5519
SUBJECT: GRB060904b: Optical observations with Swift/UVOT 
DATE:    06/09/04 14:50:10 GMT
FROM:    Samantha Oates at MSSL  <sro at mssl.ucl.ac.uk>

S. R. Oates (UCL-MSSL), D. Grupe (PSU) on behalf of the Swift UVOT team

The Swift Ultra-Violet/Optical Telescope (UVOT) began observations of 
GRB060904b at 02:32:14 UT, ~71 seconds after the initial Swift BAT trigger
(Grupe et al, GCN 5505). An optical counterpart was detected with the
V filter at a position RA(J2000)= (03h,52m,50.54s, -00o43'31.1'') to within 0.5''.
An optical afterglow was detected in V, B, U, UVW1, UVM2 and UVW2 filters.

The photometery results are given for the 6 filters below:

Filter      Tstart  Tstop   Magnitudes and UL
---------------------------------------------
V             71    316      18.64 +/-  0.33
              4732   4931     19.16 +/-  0.36
              5960   6100     18.25 3 sigma UL

B            4322   4521     18.98 +/-  0.15
              5550   5749     19.56 +/-  0.28

U            4117   4316     18.32 +/-  0.19
              5346   5545     18.65 +/-  0.23

UVW1         3913   4112     18.78 +/-  0.31
              5141   5340     19.11 +/-  0.36

UVM2         3708   3907     18.88 +/-  0.36
              4936   5135     19.66 +/-  0.55

UVW2         4528   4727     18.96 +/-  0.33
              5756   5955     19.32 +/-  0.41
---------------------------------------------

The values quoted above are not corrected for the expected
Galactic extinction of E_{B-V}=0.173.