TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3888 SUBJECT: GRB 050826: BAT refined analysis DATE: 05/08/26 21:17:04 GMT FROM: Craig Markwardt at NASA/GSFC/UMD C. Markwardt (GSFC/UMD), L. Barbier (GSFC), S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), D. Hullinger (GSFC/UMD), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), T. McMahon (Langston U.), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), J. Tueller (GSFC), N. White (GSFC) on behalf of the Swift-BAT team: Using the full data set, we report further analysis of Swift-BAT GRB 050826 (trigger # 152113) (Mangano, et al., GCN 3884). The ground-analysis position is RA,Dec 87.772, -2.667 (J2000) with an uncertainty of 2.1 arcmin (radius, 90%, stat+sys). This is 2.7 arcmin from the onboard position and 1.7 arcmin from the XRT position reported by Mangano et al. in GCN Circ. 3885. The light curve shows a peak with a FRED structure lasting until T+14, a second 4-sec peak centered at T+18, and possible lower-energy peaks at T+34 sec and T+52 sec. The main part of the burst is weak and hard in the BAT energy range. T90 is 35 +- 8 sec. Fitting a simple power law over the interval from T+1 to T+36 sec, the photon index is 1.2 +/- 0.3 with a fluence of 4.3 +/- 0.7 x 10^-7 erg/cm^2 in the 15-150 keV band (90% c.l). The peak flux in a 1-second wide window starting at T+1 sec is 0.42 +/- 0.12 ph/cm^2/sec (15-150 keV).