[vsnet-grb-info 1737] GRB 050709: Swift UVOT and XRT observations

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3577
SUBJECT: GRB 050709: Swift UVOT and XRT observations
DATE:    05/07/12 22:09:34 GMT
FROM:    Adam Morgan at PSU/Swift-UVOT  <qmorgan at gmail.com>

A. Morgan, D. Grupe, C. Gronwall, J. Racusin, A. Falcone (PSU), F. 
Marshall (GSFC), M. Chester (PSU), and N. Gehrels (GSFC) report on 
behalf of the Swift UVOT and XRT teams:

HETE detected GRB 050709 at 22:36:37 UT on 9 July 2005. (Butler et al., 
GCN 3570).  Swift executed a Target of Opportunity observation of the 
HETE position.  The Swift Ultra-Violet/Optical Telescope (UVOT) and 
X-Ray Telescope (XRT) began observations of GRB 050709 at UT 13:06:53 on 
11 July 2005, approximately 38.5 hrs after the HETE detection.

We detect no new source with either telescope within the 1.34' HETE 
error circle.  In the V filter of the UVOT, we find the following 5 
sigma and 3 sigma limiting magnitudes (in 6" radius apertures measured 
at the HETE position):

Filter    Lim_Mag      Lim_mag   Exposure time (s)   T_range (hr)
          5sigma       3sigma

V         21.08        21.64        17752            38.50 - 50.27

For XRT data, we assumed a typical spectrum.  We find the following 1 
sigma and 3 sigma upper limits (in 50" radius apertures measured at the 
HETE position):

Lim_Flux     Lim_Flux   Exposure time (s)   T_range (hr)
1sigma       3sigma

2e-14        6e-14         15243            38.50 - 50.27

The limiting flux is given in units of erg/s/cm^2.  T_range is the range 
from the HETE detection from the beginning of the first observation to 
the end of the last.

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

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