TITLE: GCN CIRCULAR NUMBER: 5053 SUBJECT: GRB 060502: Swift-BAT refined analysis DATE: 06/05/02 13:50:00 GMT FROM: Takanori Sakamoto at NASA/GSFC A. Parsons (GSFC), 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 (UMD), C. Markwardt (GSFC/UMD), D. Palmer (LANL), T. Sakamoto (GSFC/ORAU), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), on behalf of the Swift-BAT team: Using the data set from T-119 to T+229 sec from the recent telemetry downlink, we report further analysis of BAT GRB 060502 (trigger #208169) (La Parola, et al., GCN 5047). The BAT ground-calculated position is (RA,Dec) = 240.941, 66.600 deg {16h 3m 45.8s, 66d 35' 59.5"} (J2000) +- 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 49%. The mask-weighted lightcurve shows a main peak starting at T-5 sec and ending at T+30 sec. The second weak peak follows in a duration of ~15 sec. T90 (15-350 keV) is 33 +- 5 sec (estimated error including systematics). The time-averaged spectrum from T-5.8 to T+42.0 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.43 +- 0.08. The fluence in the 15-150 keV band is 2.2 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T-0.10 sec in the 15-150 keV band is 1.7 +- 0.2 ph/cm2/sec. Eiso is 5.8e+49 ergs (16.5 - 164.9 keV in the GRB rest frame) and 1.5e+52 ergs (37.7 - 376.5 keV in the GRB rest frame) using z = 0.099 (Chen et al. GCN 5051) and z = 1.51 (Cucchiara et al. GCN 5052) respectively. All the quoted errors are at the 90% confidence level.