TITLE:   GCN CIRCULAR
NUMBER:  9717
SUBJECT: GRB090726: Swift/UVOT observations
DATE:    09/07/27 16:01:04 GMT
FROM:    Wayne Landsman at GSFC/SSAI  <wayne.b.landsman@nasa.gov>

W.B. Landsman (NASA/GSFC) and K.Page (U. Leicester)report on behalf of 
the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 090726, 
3610s after the BAT trigger (Page et al., GCN Circ. 9706),  and the 
afterglow first reported by Moskvitin et al., (GCN Circ. 9709) is 
detected in the UVOT white, v, and b filters.

The initial magnitudes and upper limits are as follows:

Filter   T_start(s)  Exp(s)    Mag
white     3610       147   20.62 ± 0.18
white     4179       197   21.36 ± 0.29
v         4589       197   19.98 ± 0.36
b         3974       197   20.80 ± 0.44
u         3769       197   >20.9 (3 sigma)
uvw1      5000       197   >20.6 (3 sigma)
uvm2      4794       197   >20.6 (3 sigma)
uvw2      4385       197   >21.0 (3 sigma)

The nondetections in the u and UV filters are consistent with the 
redshift of z= 2.71 reported by Fatkhullin et al (GCN 9712)

The values quoted above are not corrected for the Galactic extinction 
due to the reddening of E(B-V) = 0.045 in the direction of the burst.
The photometry is on the UVOT photometric system described in Poole et 
al. (2008, MNRAS, 383, 627).