GCN Circular 5565

P. J. Brown (PSU) & C. P. Hurkett (U Leicester)
report on behalf of the Swift UVOT team:

Swift/UVOT began settled observations of
GRB060912 (BAT trigger 229185) at 13:57:47 UT,
113 seconds after the initial Swift BAT trigger
(Hurkett et al., GCN Circ. 5558
Not found
 
 
).  The fading
optical counterpart seen in the white finding
charts was also detected by UVOT in V, B, U, UVW1
and marginally in UVM2.  The relatively shallow
upper limit in UVW2 prevents us from constraining
the redshift well.

The magnitudes from early observations and the
upper limit in UVW2 are tabulated below.

Filter  T_range(s)    Exp(s)     Magnitude

White   113-212       100        16.0 +/- 0.1
White   859-958       100        18.1 +/- 0.1

V       219-618       400        17.4 +/- 0.1
V       964-1363      400        18.4 +/- 0.2

B       697-1776      79         19.5 +/- 0.4

U       672-691       20         17.6 +/- 0.2

UVW1    649-668       20         18.51 +/- 0.4

UVM2    624-1861      119        19.3 +/- 0.4

UVW2    725-1814      78       > 19.5 (3.0-sigma)

T_range is the span of the exposure in seconds
from the BAT trigger.

The values quoted above are not corrected for
the expected Galactic extinction corresponding
to a reddening of E(B-V)=0.05.