TITLE:   GCN CIRCULAR
NUMBER:  8757
SUBJECT: GRB 081230  Swift/UVOT Observations
DATE:    08/12/31 12:31:41 GMT
FROM:    Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>

S. R. Oates (MSSL-UCL) and V. La Parola (INAF-IASFPA) report on behalf  
of the Swift/UVOT team:

The Swift/UVOT began observerving the field of GRB 081230 132 s
after the BAT trigger ( La Parola et al., GCN Circ. 8753). We detect the
optical afterglow in the white, v, b and u filters at the position:

RA(J2000.0)  = 02:29:19.467
DEC(J2000.0) = -25:08:51.0

with an estimated uncertainty of 0.9 arcsec (radius, 90% confidence).
This position is consistent with the UVOT-enhanced XRT position  
(Osborne et al., GCN 8756)
and the optical afterglow position reported by ROTSE-III (Yuan et al.,  
GCN 8754).

The magnitudes and 3 sigma upper limits are reported below:

Filter    T_start (s) T_stop  Exposure    Mag/3sig UL
------------------------------------------------------------
white       4060  4210   147   20.45 +/- 0.35
v	         587    607     19     18.30 +/- 0.48
b	         388    408     19     18.92 +/- 0.36
u	         132    382     246   20.28 +/- 0.38
u	         511    531 	19     19.04 +/- 0.52
uvw1	 487    5854   435   > 21.23
uvm2       462    5649   255   > 20.95
uvw2       414	    6575   353   > 21.44
------------------------------------------------------------

The above magnitudes are not corrected for the Galactic extinction
corresponding to a reddening of E_{B-V} = 0.01 mag (Schlegel et al.,
1998, ApJS, 500, 525). The photometry is on the UVOT flight system
described in Poole et al. (2008, MNRAS, 383,627).