TITLE: GCN CIRCULAR NUMBER: 9138 SUBJECT: GRB 090417A: Swift-BAT refined analysis DATE: 09/04/17 19:50:47 GMT FROM: Scott Barthelmy at NASA/GSFC W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), V. Mangano (INAF-IASFPA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-119 to T+261 sec from recent telemetry downlinks, we report further analysis of BAT GRB 090417A (trigger #349447) (Mangano, et al., GCN Circ. 9133). The BAT ground-calculated position is RA, Dec = 34.993, -7.141 deg which is RA(J2000) = 02h 19m 58.3s Dec(J2000) = -07d 08' 28.9" with an uncertainty of 2.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 30%. The mask-weighted light curve shows a single peak starting at T-0.06 sec, peaking at T+0.04 sec, and ending at T+0.09 sec. There appears to be no extended emmission out to T+55 sec, at which point the burst location went out of the BAT FOV during a planned target slew. T90 (15-350 keV) is 0.072 +- 0.018 sec (estimated error including systematics). The time-averaged spectrum from T-0.0 to T+0.1 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index -0.65 +- 2.11, and Epeak of 40.3 +- 12.7 keV (chi squared 67.41 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.9 +- 0.5 x 10^-8 erg/cm2 and the 1-sec peak flux measured from T-0.46 sec in the 15-150 keV band is 3.6 +- 1.0 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.99 +- 0.36 (chi squared 77.85 for 57 d.o.f.). 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/349447/BA/