TITLE: GCN CIRCULAR NUMBER: 10803 SUBJECT: GRB 100526B: Swift-BAT refined analysis DATE: 10/05/26 21:58:32 GMT FROM: Scott Barthelmy at NASA/GSFC J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. H. Siegel (PSU), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 100526B (trigger #423184) (Siegel, et al., GCN Circ. 10799). The BAT ground-calculated position is RA, Dec = 0.777, -37.913 deg, which is RA(J2000) = 00h 03m 06.5s Dec(J2000) = -37d 54' 48.4" with an uncertainty of 3.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 95%. The mask-weighted light curve shows a broad weak peak starting at ~T-25 sec, peaking around T+10 sec, and ending around t+50 sec. The burst location went out of the BAT FOV at T+240 sec when Swift was forced to slew due to an observing constraint. T90 (15-350 keV) is 64.0 +- 22.6 sec (estimated error including systematics). The time-averaged spectrum from T-28.4 to T+35.6 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.47 +- 0.28. The fluence in the 15-150 keV band is 4.7 +- 0.9 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+11.15 sec in the 15-150 keV band is 0.1 +- 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/423184/BA/