TITLE: GCN CIRCULAR NUMBER: 21156 SUBJECT: GRB 170526A, Swift-BAT refined analysis DATE: 17/05/27 18:52:59 GMT FROM: Amy Lien at GSFC C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), T. Sakamoto (AGU), B. Sbarufatti (INAF-OAB/PSU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-327 to T+1275 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170526A (trigger #754549) (Sbarufatti et al., GCN Circ. 21149). The BAT ground-calculated position is RA, Dec = 4.723, 1.277 deg which is RA(J2000) = 00h 18m 53.6s Dec(J2000) = +01d 16' 35.7" with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 94%. The mask-weighted light curve shows a weak pulse structure that starts at ~T0, peaks at ~ T+1 s, and ends at ~ T+10 s. T90 (15-350 keV) is 7.9 +- 1.6 sec (estimated error including systematics). The time-averaged spectrum from T+1.1 to T+10.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.25 +- 0.42. The fluence in the 15-150 keV band is 1.6 +- 0.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+1.10 sec in the 15-150 keV band is 0.3 +- 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/754549/BA/