TITLE: GCN CIRCULAR NUMBER: 28193 SUBJECT: AX J1846.4-0258: Swift-BAT refined analysis DATE: 20/08/02 19:00:05 GMT FROM: Amy Lien at GSFC S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), 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-239 to T+722 sec from the recent telemetry downlink, we report further analysis of the SGR-like burst from AX J1846.4-0258/PSR J1846-0258 (trigger #985320) (Krimm et al., GCN Circ. 28187). The BAT ground-calculated position is RA, Dec = 281.633, -3.006 deg which is RA(J2000) = 18h 46m 32.0s Dec(J2000) = -03d 00' 20.9" with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a single pulse structure that starts at ~T0, peaks at ~T+0.007 s, and ends at ~T+0.012. T90 (15-350 keV) is 0.012 +- 0.006 sec (estimated error including systematics). The source went out of the BAT field of view at ~T+130 s. The time-averaged spectrum from T+0.00 to T+0.012 sec fit by a simple power-law model shows the power law index of 3.05 +- 0.28 (chi squared 50.60 for 57 d.o.f.). The fluence in the 15-150 keV band is 1.2 +- 0.2 x 10^-8 erg/cm2. A single blackbody fit to the time-averaged spectrum shows the blackbody temperature of 6.31 +- 0.99 keV (chi squared 39.29 for 57 d.o.f.). A thermal bremsstrahlung model fit shows the temperature of 24.18 +- 6.24 keV (chi squared 40.51 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/985320/BA/