[vsnet-grb-info 8376] GRB 090904A: Swift/UVOT Refined Analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9899
SUBJECT: GRB 090904A: Swift/UVOT Refined Analysis
DATE:    09/09/05 05:46:33 GMT
FROM:    Tyler Pritchard at PSU  <tapritchard at astro.psu.edu>

T. A. Pritchard (PSU), C. A. Swenson (PSU) and M. Perri (ASDC) report on 
behalf of the
Swift/UVOT team:

The Swift/UVOT began settled observations of GRB 090904A,  141 seconds 
after the
BAT trigger (M. Perri et al., GCN Circ. 9879). We do not detect any 
source at the
UVOT-enhanced XRT position (M.R. Goad, GCN Circ. 9885).

The 3-sigma upper limits for the exposures are:

Filter   T_start(s)   T_stop(s)   Exp(s)  Mag (3-sigma upper limit)
-------------------------------------------------------------
white      141      	1189       341      > 21.57
v          629       	1078        58      > 18.72
b          555          1177        58      > 19.59
u          299       	1152       285      > 20.43
uvw1	   679		1127	    58      > 19.11
uvm2	   827		847	    19      > 17.61
uvw2	   605		1054	    58      > 19.17
-------------------------------------------------------------

The quoted upper limits have not been corrected for the expected
Galactic extinction corresponding to a reddeningalong the line of sight of
E_(B-V) = 0.1 mag (Schlegel et al., 1998, ApJS, 500, 525).  All 
photometry is on the
UVOT photometric system described in Poole et  al. (2008, MNRAS, 383, 627).