TITLE: GCN CIRCULAR NUMBER: 11757 SUBJECT: GRB 110223B: Swift-BAT refined analysis DATE: 11/02/24 04:32:27 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-120 to T+293 sec from recent telemetry downlinks, we report further analysis of BAT GRB 110223B (trigger #446677) (Stamatikos, et al., GCN Circ. 11754). The BAT ground-calculated position is RA, Dec = 150.340, -68.329 deg, which is RA(J2000) = 10h 01m 21.6s Dec(J2000) = -68d 19' 44.3" with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows the burst start with a small peak at ~T-45 sec, a slightly larger peak at ~T+2 sec out to ~T+20 sec, with on-going low-level emission out to ~T+150 sec. T90 (15-350 keV) is 54.0 +- 8.5 sec (estimated error including systematics). The time-averaged spectrum from T-45 to T+20 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.65 +- 0.21. The fluence in the 15-150 keV band is 6.1 +- 0.8 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.99 sec in the 15-150 keV band is 0.6 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/446677/BA/