TITLE:   GCN CIRCULAR
NUMBER:  11237
SUBJECT: GRB 100905A: Swift/UVOT Upper Limits
DATE:    10/09/06 19:08:45 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@astro.psu.edu>

M. H. Siegel (PSU) and F. E. Marshall (NASA/GSFC) report on behalf
of the Swift/UVOT team.

The Swift/UVOT began settled observations of the field of
GRB 100905A 77s after the BAT trigger (Marshall et al.,
GCN Circ. 11214).  Data summed from the first and second orbits
do not reveal a source at the enhanced position of the X-ray
afterglow (Evans et al., GCN Circ. 11219).

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      78        228        147        >20.77
white         78       2055        450        >21.29
V            619       1933        155        >19.01
B            545       2031        155        >19.81
u fc         290        540        245        >20.08
u            290       2006        381        >20.17
uvw1         668       1982        155        >19.53
uvm2        5654       7290        393        >20.19
uvw2        5245      12865       1278        >21.26
=======================================================

The above magnitudes are not corrected for the Galactic extinction
corresponding to a reddening of E_{B-V} = 0.06 (Schlegel et al.,
1998, ApJS, 500, 525). The photometry is on the UVOT photometric
system described in Poole et al. (2008, MNRAS, 383, 627).