NASA SWIFT: Swift detection of GRB 050717

TITLE: GCN GRB OBSERVATION REPORT
NUMBER: 3633
SUBJECT: Swift detection of GRB 050717
DATE: 05/07/17 11:28:50 GMT
FROM: Cheryl Pauline Hurkett at Leicester U cph9@star.le.ac.uk

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.