GCN Circular 3633

C. Hurkett, K. Page, (U. Leicester), J. Kennea, D. Burrows (PSU), A.
Blustin (MSSL), L. Barbier (GSFC), C. Markwardt (GSFC/UMd), A. Parsons
(GSFC) and N. Gehrels (GSFC) report on behalf of the Swift team;

At 10:30:52.21 UT, the Swift Burst Alert Telescope (BAT) triggered and
located on-board GRB 050717 (trigger # 146372). The BAT on-board
calculated location is RA, Dec 214.332, -50.539 (14h 17m 20s, -50d 32'
21") (J2000) with an uncertainty of 3 arcmin (radius, 4-sigma, including
estimated systematic uncertainty). The BAT light curve showed an initial
spike, then a strong peak followed by a decay out to about 20 seconds
(FRED). The peak count rate was measured by BAT to be ~16000 counts/sec at
T+4 sec in the 15 - 350 keV band.

The spacecraft slewed immediately and the XRT began observing the burst at
10:32:11.49 UT (approximately 79 seconds after the BAT trigger). The XRT
was unable to centroid on the burst, however, the downlinked X-ray
spectrum and lightcurve show that there is a bright X-ray object in the
field that appears to be fading.

The Swift Ultra Violet/Optical Telescope (UVOT) observations began at
10:32:10.7 UT (78 seconds after the BAT trigger).  The first data taken
after the spacecraft settled was a 100 sec exposure using the V filter
with the midpoint of the observation at 128 sec after the BAT trigger.
Based on comparisons to the DSS, we detect no new source within the BAT
error circle. The 3-sigma upper limit in the V-filter is approximately
18.71 mag.