TITLE:   GCN CIRCULAR
NUMBER:  9177
SUBJECT: GRB 090419: Swift/UVOT Observations
DATE:    09/04/20 20:31:07 GMT
FROM:    Michael Siegal at Swift/PSU  <siegel@astro.psu.edu>

M. H. Siegel (PSU), E. A. Hoversten (PSU) and G. Stratta (ASDC) report
on behalf of the Swift/UVOT team.

The Swift/UVOT began observing the field of GRB 090419 126s after the
BAT trigger (Stratta et al., GCN Circ. 9161).  Data summed over the  
first
orbit reveals a very faint (3.3 sigma) source in the white filter at the
refined position of the X-ray afterglow (Osborne et al., GCN Circ.  
9164).
This source is not detected in the second orbit data.

The detection and 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    126          276        147        > 20.69
white       126         1706        410          21.07+-0.31
white      5320         6956        393        > 21.25

v           614         1756        136        > 18.93
v          5732         7367        393        > 19.60

b           540         1682        116        > 19.87
b          5116        13394        572        > 20.69

u           284         1829        362        > 20.25
u          6346        13206       1081        > 20.89

uvw1        664         1805        136        > 19.31
uvw1       6142        12292       1118        > 20.63

uvm2        639         1608         58        > 18.41
uvm2       5936        17728        465        > 19.99

uvw2        590         1731        136        > 19.37
uvw2       5527         7162        393        > 20.13
=============================================================

The above magnitudes are not corrected for the Galactic extinction
corresponding to a reddening of E_{B-V} = 0.296 (Schlegel et al.,
1998, ApJS, 500, 525). The photometry is on the UVOT photometric system
described in Poole et al. (2008, MNRAS, 383, 627).