//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6691 SUBJECT: GRB 070731, Swift-BAT refined analysis DATE: 07/07/31 14:00:59 GMT FROM: Scott Barthelmy at NASA/GSFC J. Tueller (GSFC), L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), P. Romano (INAF/OAB), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), T. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+302 sec from the recent telemetry downlink, we report analysis of BAT GRB 070731 (trigger #286574). The spacecraft did not slew to the location because of a Moon constraint. It will come out of Moon constraint 02 Aug 07 UT. The BAT ground-calculated position is RA, Dec = 328.581, -15.740 deg which is RA(J2000) = 21h 54m 19.5s Dec(J2000) = -15d 44' 23" with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 49%. The mask-weighted lightcurve shows a single peak starting at ~T-0.5 sec, peaking at ~T+0.7, and ending at ~T+3 sec. There is no indication of any other emission prior and past the trigger. We note that there is a gap in the currently downloaded data set from T+120 to T+190 sec. T90 (15-350 keV) is 2.9 +- 0.2 sec (estimated error including systematics). The time-averaged spectrum from T-0.1 to T+3.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.65 +- 0.23. The fluence in the 15-150 keV band is 1.6 +- 0.3 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.14 sec in the 15-150 keV band is 1.2 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. This burst occurred during a 42-min outage in the TDRSS service and so all the normal real-time messages were not sent to the ground. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6765 SUBJECT: GRB 070731: Swift/UVOT Upper Limit DATE: 07/08/27 13:21:53 GMT FROM: Frank Marshall at GSFC F.E. Marshall (NASA/GSFC) and A. Moretti (INAF-OAB) report on behalf of the Swift team: The Swift/UVOT observed the field of GRB 070731 starting 144 ks after the BAT trigger (Tueller et al., GCN Circ. 6691), which occurred at 09:33:22 UT (Moretti et al., GCN Report 79.1). All of the UVOT exposures used the White (160-650 nm) filter, and the final exposure started 219 ks after the trigger. No XRT source was detected (Moretti et al., GCN Report 79.1) inside the BAT error circle, and we do not find any afterglow candidate inside the BAT error circle in the UVOT observations. The first long (1154 s) exposure that covered the entire BAT error circle started 155 ks after the BAT trigger. The 3-sigma upper limit for detecting a source is 20.9 mag. (uncorrected for the expected Galactic extinction corresponding to a reddening of E(B-V) = 0.04 mag in the direction of the burst (Schlegel et al. 1998)).