TITLE: GCN CIRCULAR NUMBER: 7109 SUBJECT: GRB 071118, Swift-BAT refined analysis DATE: 07/11/18 20:39:20 GMT FROM: Scott Barthelmy at NASA/GSFC C. Markwardt (GSFC/UMD), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), D. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+303 sec from the recent telemetry downlink, we report further analysis of BAT GRB 071118 (trigger #296856) (Cummings, et al., GCN Circ. 7106). The BAT ground-calculated position is RA, Dec = 299.839, 70.130 deg, which is RA(J2000) = 19h 59m 21.4s Dec(J2000) = 70d 07' 47" with an uncertainty of 2.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a broad single peak starting at ~T-25 sec, peaking at ~T+55 sec, and ending at ~T+110 sec. T90 (15-350 keV) is 71 +- 20 sec (estimated error including systematics). The time-averaged spectrum from T+4.5 to T+81.2 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.63 +- 0.29. The fluence in the 15-150 keV band is 5.0 +- 1.0 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+80.26 sec in the 15-150 keV band is 0.3 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level. This burst satisfies Sakamoto/Ukwatta Swift-BAT possible high-z criteria: 1) Power law photon index = 1.63 (PL photon index < 2) 2) 1-s peak photon flux = 0.3 (1-s peak photon flux < 1.0 ph/cm2/s) 3) Light curve variance = 4e-05 (Variance < 0.0001) 4) T90/(Peak photon flux) = 220 (T90/(Peak photon flux) > 200) Based on a limited sample of bursts, these criteria yield an 85% chance it has a redshift greater than 3.5. Deep IR observations are strongly encouraged.