TITLE: GCN CIRCULAR NUMBER: 22755 SUBJECT: GRB 180602A: Swift-BAT refined analysis DATE: 18/06/02 17:18:13 GMT FROM: Amy Lien at GSFC A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), S. B. Cenko (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180602A (trigger #835200) (Cenko et al., GCN Circ. 22752). The BAT ground-calculated position is RA, Dec = 142.343, 32.080 deg which is RA(J2000) = 09h 29m 22.4s Dec(J2000) = +32d 04' 48.1" with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 78%. The mask-weighted light curve shows a single-peaked structure that starts at ~T-30 s, peaks at ~T-20 s, and ends at ~T+25 s. We note that the burst emission indeed started and peaked during a pre-planned spacecraft slew, and the trigger occurred near the end of the pulse when the slew settled. T90 (15-350 keV) is 45.4 +- 7.1 sec (estimated error including systematics). The time-averaged spectrum from T-29.32 to T+25.73 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.72 +- 0.11. The fluence in the 15-150 keV band is 1.6 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-20.12 sec in the 15-150 keV band is 0.9 +- 0.2 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/835200/BA/