TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3759
SUBJECT: GRB050803: Optical/UV Upper Limits from Swift-UVOT
DATE:    05/08/04 17:06:57 GMT
FROM:    Peter Brown at PSU  <pbrown@astro.psu.edu>

GRB050803: Optical/UV Upper Limits from Swift-UVOT

P. J. Brown (PSU), D.L. Band (GSFC-UMBC),
P. Boyd (GSFC-UMBC), J. Norris (GSFC),
K. Hurley (Berkeley), N. Gehrels (GSFC),
report on behalf of the Swift-UVOT Team:

Swift detected and slewed immediately to the
position of GRB050803 (trigger=148833;
Band et al. GCN 3748).  UVOT began settled
observations at 19:17:05.2 UT, 185 seconds
after the trigger.  No sources are detected
within the revised XRT error circle
(Racusin et al GCN 3752) in any of our images.
The following are 3 sigma upper limits at the
indicated epochs.

Filter  Tmid(sec)  Tmid(h)  Exp(sec)  UppLim(3-sigma)
V       235.09     0.07     99.78     18.8
V       365.14     0.1      9.76      17.5
V       1357.88    0.38     99.72     18.5
V       11900.74   3.31     899.76    20.0

B       336.31     0.09     9.77      18.5
B       1148.34    0.32     99.77     19.7
B       6919.71    1.92     693.82    20.7
B       18490.49   5.14     695.69    20.7

U       322.1      0.09     9.76      18.3
U       1043.66    0.29     99.77     19.5
U       6115.3     1.7      899.77    20.7
U       17685.21   4.91     899.77    20.7

UVW1    308.4      0.09     9.79      18.7
UVW1    5208.39    1.45     899.77    21.1
UVW1    16778.3    4.66     899.76    21.1

UVM2    294.29     0.08     9.79      18.5
UVM2    1446.35    0.4      68.22     19.5
UVM2    12705.06   3.53     694.85    20.9

UVW2    351.49     0.1      9.78      19.4
UVW2    1253.64    0.35     99.77     20.2
UVW2    10993.89   3.05     899.78    21.5

In addition, no sources are detected within the
XRT error circle when the above images are summed
together, including those reported by Bloom et al
(GCN 3758) and Berger et al (GCN 3753).

These magnitudes are based on preliminary zero-points,
measured in orbit, and will require refinement with
further calibration.