[vsnet-grb-info 3719] GRB 060908: Swift/UVOT Observations

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5553
SUBJECT: GRB 060908: Swift/UVOT Observations
DATE:    06/09/08 15:14:26 GMT
FROM:    Adam Morgan at PSU/Swift-UVOT  <qmorgan at gmail.com>

A. N. Morgan (PSU),  D. E. Vanden Berk (PSU), P. Brown (PSU) and P. A.
Evans (U Leicester) report on behalf of the Swift UVOT team:

The Swift/UVOT began observations of GRB 060908 at 08:58:42 UT, ~80
seconds after the initial Swift BAT trigger (Evans et al., GCN Circ.
5544). An optical counterpart was detected with the V filter at a
position RA(J2000) = (02h 07m 18.36s,+00d 20' 31.2") to within 0.7".

An optical afterglow was detected in the White, V, B, U, and UVW1 filters.

The best estimate for the photometric redshift is z=1.62 assuming an
SMC extinction law with E(B-V)=0.05, but it is poorly constrained.
Values range from z=0.26-2.20 for a 90% confidence range.

The photometry was performed using a 6 arcsec radius aperture and is
reported below:

Filter  T_range(s)    Exp. (s)   Magnitude
White   80-179        99.8       15.06 +/- 0.03
White   5839-6038     199.8      19.57 +/- 0.22

V       185-584       399.8      16.85 +/- 0.05
V       4816-6448     399.6      19.44 +/- 0.36

B       663-820       19.6       18.41 +/- 0.31
B       5635-7129     262.5      > 20.03 (3.0-sigma)

U       639-658       19.7       17.01 +/- 0.16
U       786-805       19.8       17.99 +/- 0.32

UVW1    615-782       39.6       18.61 +/- 0.35
UVW1    5226-6857     399.6      > 20.24 (3.0-sigma)

UVM2    591-758       39.6       > 18.57 (3.0-sigma)
UVM2    5021-6652     399.6      > 20.54 (3.0-sigma)

UVW2    691-858       39.6       > 19.07 (3.0-sigma)
UVW2    4612-6243     399.6      > 20.71 (3.0-sigma)

The values quoted above are not corrected for the expected Galactic
extinction of E(B-V)=0.03.