TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3637 SUBJECT: GRB 050717: Swift-BAT refined analysis DATE: 05/07/17 17:39:19 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift J. Cummings (GSFC/NRC), L. Barbier (GSFC), S. Barthelmy (GSFC), E. Fenimore (LANL), N. Gehrels (GSFC), K. Gendreau (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), P. Meszaros (PSU), T. Mitani (ISAS), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), M. Suzuki (Saitama), J. Tueller (GSFC), on behalf of the Swift/BAT team: At 10:30:52.21 UT Swift-BAT detected GRB 050717 (trigger=146372) (GCN Circ 3633, C. Hurkett et al.). The refined BAT ground position is (RA,Dec) = 214.352, -50.541, [deg; J2000] +- 3 arcmin, (90% containment). The partial coding was 55%. The masked-weighted light curve shows a large peak (starting at T+2.4 sec and reaching a maximum at T+2.8 sec), followed by an exponential decay with several smaller peaks. There are two much smaller precursor peaks at T+0 and T+0.7 sec, each with a 15-350 keV fluence of ~7 x 10^-8 erg/cm2. BAT triggered on the first these two precursor peaks. T90 (15-350 keV) is (86 +- 2) sec (estimated error including systematics). The power-law photon index of the time-averaged spectrum is 1.42 +- 0.05. The fluence in the 15-350 keV band is (1.27 +- 0.05) x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+2.8 sec in the 15-350 band is (8.5 +- 0.4) ph/cm2/sec. All the quoted errors are at the 90% confidence level.