TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4200
SUBJECT: GRB051105A: Swift/UVOT Observations
DATE:    05/11/06 00:29:13 GMT
FROM:    Peter Brown at PSU  <pbrown@astro.psu.edu>

P.J. Brown (PSU), T. Mineo (INAF-IASFPA), M. Chester (PSU),
L. Angelini (GSFC-JHU),  P. Meszaros (PSU), & N. Gehrels (GSFC)
on behalf of the Swift/UVOT team report:

The Swift-UVOT began observing the field of
GRB 051105A (BAT Trigger=162580; Mineo et al. GCN 4188)
at 2005-11-05 6:27:47, 66 seconds after the burst.

No new source with respect to the DSS is visible in the
2.5' revised BAT error circle (Barbier et al. GCN 4194)
during the first 200 second image (Tmid=166 seconds
after the burst) down to a 5 sigma
limiting magnitude of V=18.4.  Using summed images,
we also do not detect a new source in any of our 6 filters
down to the following 5-sigma magnitude upper limits:

Filter  T_range(sec)   Exp(sec)  5sigUL
V       66-19067       2198      20.0
B       433-13687      961       20.6
U       379-25257      1345      20.5
W1      325-25103      2098      20.0
M2      271-24196      2303      20.4
W2      542-18160      2042      20.4
White   487-915        100       19.4

Where T_range is time post-trigger.

At the position of XRT's SR1 (Mineo et al. GCN 4195), we marginally detect the
brighter source (with counterpart in DSS) seen by Klose, Laux, & Stecklum (GCN
4196) but not the fainter source.

We also detect the extended galaxy mentioned by Klose, Laux, & Stecklum (GCN
4196) to the east of SR1 in the optical filters and derive the following
magnitudes and 3 sigma upper limits: V=19 +/- 0.1, B=20.4 +/- 0.2, U=20.5 +/-
0.2, UVW1>20.6, UVM2>21.0, UVW2>21.0.  The non-detection of the galaxy in the
UV is not necessarily due to redshift, as the limits are not that deep, but
might indicate that there is not a high star formation rate in this galaxy.

XRT positions SR2,3,4 (Mineo et al. GCN 4195) each contain an optical
counterpart (visible in the DSS) within the north edge of the error circle.
They are outside the revised BAT error circle as mentioned by Klose, Laux, &
Stecklum (GCN 4196).

We do not detect a source at the position of the radio source detected by Frail
& Cameron (GCN 4199).

Further observations and analysis are underway.