TITLE: GCN CIRCULAR NUMBER: 23000 SUBJECT: GRB 180720C: Swift-BAT refined analysis DATE: 18/07/21 19:01:08 GMT FROM: Amy Lien at GSFC J. R. Cummings (CPI), S. D. Barthelmy (GSFC), H. A. Krimm (NSF/USRA), S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC), 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-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180720C (trigger #848932) (LaPorte et al., GCN Circ. 22982). The BAT ground-calculated position is RA, Dec = 265.655, -26.634 deg which is RA(J2000) = 17h 42m 37.1s Dec(J2000) = -26d 38' 02.5" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 98%. The mask-weighted light curve shows a main single-pulse structure that starts at ~T-20 s, peaks at ~T0, and ends at ~T+20 s. In addition, there are some weak emission prior to this main pulse, starting at ~T-150 s. T90 (15-350 keV) is 124.2 +- 32.7 sec (estimated error including systematics). The time-averaged spectrum from T-150.52 to T+23.34 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.39 +- 0.13. The fluence in the 15-150 keV band is 2.4 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.27 sec in the 15-150 keV band is 1.1 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The temporal and spectral characteristics of this burst are consistent with those of a long GRB. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/848932/BA/