TITLE:   GCN CIRCULAR
NUMBER:  11272
SUBJECT: GRB 100909A: Swift/UVOT observations
DATE:    10/09/10 21:19:23 GMT
FROM:    Massimiliano de Pasquale at MSSL-UCL  <mdp@mssl.ucl.ac.uk>

M. De Pasquale (MSSL-UCL) and M. H. Siegel (PSU) report, on behalf
of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of
GRB 100909A 11747 s after the INTEGRAL trigger (Mereghetti et
`al.,GCN Circ. 11260). Data summed from the first and second orbits
do not reveal a source at the enhanced position of the X-ray
afterglow (Gelbold et al., GCN Circ. 11268).

The 3-sigma upper limits f are reported below:

FILTER T_start(s) T_stop    Exposure   Mag/3UL
========================================================
wh      11747     25861     1809       >21.9
v       14755     18362      894       >20.21
b       11906     44659     1770       >21.48
u       33619     34527      885       >20.84
w1      19275     20040      752       >20.39
w2      13732     14301      561       >20.33
=======================================================

  The above magnitudes are not corrected for the strong Galactic
extinction corresponding to a reddening of E_{B-V} = 0.51 (Schlegel
et al., 1998, ApJS, 500, 525). The photometry is on the UVOT
photometric system described in Poole et al. (2008, MNRAS, 383, 627).