TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5174 SUBJECT: GRB 060526: Refined analysis of the Swift-BAT burst DATE: 06/05/27 17:51:50 GMT FROM: Scott Barthelmy at NASA/GSFC C. Markwardt (GSFC/UMD), L. Barbier (GSFC), S. Barthelmy (GSFC), J. Cummings (GSFC/ORAU), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), M. Koss (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/JSPS/USRA), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC) on behalf of the Swift-BAT team: Using the data set from T-119 to T+1000 sec from recent telemetry downlinks, we report further analysis of BAT GRB 060526 (trigger #211957) (Campana, et al., GCN 5162 & 5163). The BAT ground-calculated position is RA,Dec = 232.838,+0.292 deg {15h 31m 21.0s,+0d 17' 32.9"} (J2000) +- 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 61%. As noted in GCN 5163, there are two well separated episodes of emission detected in the BAT instrument. The initial emission contains two FRED-like peaks, the first starting at T-3sec, peaking at T+1, and ending at T+5 sec; and the second starts at T+6 sec, peaks at T+7 sec, and returns back to the background level at T+13 sec. T90 (15-350 keV) for this first episode is 13.8 +- 2 sec (estimated error including systematics). The scond episode consists of a single symmetric peak at T+250 sec (230 to 270 sec). This second episode is coicident with the XRT flare described in GCN 5168. For the first episode, the time-averaged spectrum from T-1.3 to T+17.0 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.66 +- 0.20. The fluence in the 15-150 keV band is 4.9 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.17 sec in the 15-150 keV band is 1.7 +- 0.2 ph/cm2/sec. For the second episode, the time-averaged spectrum from T+230 to T+270 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.07 +- 0.18. The fluence in the 15-150 keV band is 5.9 +- 0.6 x 10^-7 erg/cm2. This is slightly more fluence than the first episode, but only about half the peak flux. All the quoted errors are at the 90% confidence level.