TITLE: GCN CIRCULAR NUMBER: 11690 SUBJECT: Swift-BAT refined analysis of outburst from 1E 1841-04.5 DATE: 11/02/10 14:27:24 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC) (i.e. the Swift-BAT team): Using the data set from T-239 to T+221 sec from recent telemetry downlinks, we report further analysis of the outburst from 1E 1841-04.5 (trigger #445033) (Barthelmy, et al., GCN Circ. 11673). The BAT ground-calculated position is RA, Dec = 280.332, -4.939 deg, which is RA(J2000) = 18h 41m 19.7s Dec(J2000) = -04d 56' 19.9" with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 97%. The mask-weighted light curve shows two pairs of overlapping peaks starting at ~T-0.02 and ending at ~T+0.15 sec. T90 (15-350 keV) is 0.1 +- 0.0 sec (estimated error including systematics). The time-averaged spectrum from T-0.008 to T+0.144 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index -0.26 +- 0.66, and Epeak of 42.2 +- 3.2 keV (chi squared 54.4 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 7.5 +- 0.6 x 10^-8 erg/cm2 and the 1-sec peak flux measured from T-0.43 sec in the 15-150 keV band is 1.3 +- 0.1 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/445033/BA/