[vsnet-grb-info 7536] Swift/UVOT observations of GRB090404

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9094
SUBJECT: Swift/UVOT observations of GRB090404
DATE:    09/04/05 12:56:40 GMT
FROM:    Patricia Schady at MSSL/Swift  <ps at mssl.ucl.ac.uk>

S. R. Oates (MSSL-UCL) and H. Ziaeepour report on behalf of the Swift/UVOT 
team:

The Swift/UVOT began observing the field of GRB 090404 96 s after the BAT 
trigger (Ziaeepour et al., GCN Circ. 9086). No optical afterglow is 
detected in the initial UVOT exposures at the refined position of the 
X-ray afterglow (Beardmore et al., GCN Circ. 9088).

The 3 sigma upper limits for the finding chart (fc) and summed exposures 
are reported below.

Filter    T_start (s) T_stop  Exposure      Mag/3UL
---------------------------------------------------
white fc     96         246     147         < 20.92
white	     591        1189    206         < 20.82
white        5121       18611   1084        < 21.80

u fc	     310        559     246         < 20.17
u    	     715        1140    39          < 18.60
u            4710       35856 	3049	    < 21.56

v 	     641        1239    78          < 18.58
v            5531       11198 	1150	    < 20.37

b   	     565        1164    58          < 19.35
b            4915       35968 	2078	    < 21.50

uvw1         691        1116    39          < 18.45
uvw1         4504       45467 	3237	    < 21.47

uvm2 	     665        1091    58          < 18.54
uvm2         5736       41754 	2695	    < 21.42

uvw2 	     616        1214    78          < 19.09
uvw2         5326       6965  	393 	    < 20.28

The above magnitudes are not corrected for the Galactic extinction 
corresponding to a reddening of E_{B-V} = 0.02 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).