TITLE: GCN CIRCULAR NUMBER: 20622 SUBJECT: GRB 170206B: Swift-BAT refined analysis DATE: 17/02/07 13:47:54 GMT FROM: Amy Lien at GSFC A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), N. Gehrels (GSFC), 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+359 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170206B (trigger #737125) (Lien et al., GCN Circ. 20618). The BAT ground-calculated position is RA, Dec = 271.784, 11.175 deg which is RA(J2000) = 18h 07m 08.2s Dec(J2000) = +11d 10' 28.3" with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 78%. The mask-weighted light curve shows a weak pulse that starts at ~T0 and ends at ~T+15 s. T90 (15-350 keV) is 13.36 +- 2.67 sec (estimated error including systematics). The time-averaged spectrum from T-0.33 to T+15.53 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.42 +- 0.27. The fluence in the 15-150 keV band is 3.2 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.32 sec in the 15-150 keV band is 0.4 +- 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/737125/BA/