TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3931
SUBJECT: GRB050906: P60 Observations
DATE:    05/09/06 18:43:23 GMT
FROM:    Derek Fox at PSU  <dfox@astro.psu.edu>

Derek B. Fox (Penn State), S. Bradley Cenko (Caltech) and Brian
P. Schmidt (RSAA, ANU) report on behalf of a larger collaboration:

"The Robotic Palomar 60-Inch Telescope (P60) responded automatically
to the Swift localization of the possible GRB050906 (Trigger #153866;
Krimm et al., GCN 3926) and began imaging 114s after the burst.  No
new sources are apparent in the individual images by comparison to the
second-generation DSS.  At the mean epochs of our coadded R-band and
i-band images, we can set the following limits on the magnitude of any
new point source within the Swift/BAT localization region:

    Time (UT)    Delta     Limit (mag)
   ===================================
    10:39:55    +7m50s      R > 19.7
    10:41:41    +9m36s      I > 19.8
    11:04:32   +32m27s      R > 20.4
    11:07:49   +35m44s      I > 20.5
   ===================================

Photometric zero-points are derived from the USNO-B1.0 catalog R-band
and I-band magnitudes for this field for our R- and i-filter images,
respectively.

Moreover, we note that there is no new point source apparent near
or superposed on the bright galaxy inside the BAT error circle
(Levan & Tanvir, GCN 3927) by comparison to the DSS."