[AAVSO-HEN] GRB 091109B: Swift/UVOT Upper Limits

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
For an archive and more information on circulars visit:
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TITLE:   GCN CIRCULAR
NUMBER:  10157
SUBJECT: GRB 091109B: Swift/UVOT Upper Limits
DATE:    09/11/10 12:35:35 GMT
FROM:    Samantha Oates at MSSL  <sro at mssl.ucl.ac.uk>

S. R. Oates (MSSL-UCL) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of
GRB 091109B 84s after the BAT trigger (Oates et al., GCN 10148).
We do not detect any source at the enhanced Swift XRT position
(Evans et al. GCN 10151) and at the location of source A detected
by the VLT (Levan et al. GCN 10154, Malesani et al. GCN 10156)

The 3-sigma upper limits for the finding chart exposures (FC)
and summed images are:

Filter   T_start   T_stop   Exp(s)  Mag (3-sigma upper limit)
-------------------------------------------------------------
white (FC)  84     234       147         > 21.25
u     (FC)  296    546       246         > 20.29
white       577    18629     1313        > 22.09
v           627    11274     1172        > 20.96
b           553    17890     1337        > 21.78
u           701    23171     1761        > 21.61
uvw1        677    22710     1988        > 21.44
uvm2        652    12179     1160        > 20.87
uvw2        603    7050      471         > 20.52
-------------------------------------------------------------

The quoted upper limits have not been corrected for the expected
Galactic extinction along the line of sight of E_(B-V) = 0.17 mag.
All photometry is on the UVOT photometric system described in Poole et
al. (2008, MNRAS, 383, 627).