TITLE: GCN CIRCULAR NUMBER: 28599 SUBJECT: SGR 1830-0645: Swift-BAT refined analysis DATE: 20/10/11 17:36:47 GMT FROM: Amy Lien at GSFC H. A. Krimm (NSF), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), K. L. Page (U Leicester), 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-240 to T+962 sec from the recent telemetry downlink, we report further analysis of SGR 1830-0645 (trigger #999571) (Page et al., GCN Circ. 28594). The BAT ground-calculated position is RA, Dec = 277.697, -6.761 deg which is RA(J2000) = 18h 30m 47.3s Dec(J2000) = -06d 45' 40.0" with an uncertainty of 2.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 89%. The mask-weighted light curve shows a single-pulse structure that starts at ~T0, peaks at ~T+0.005 s, and ends at ~T+0.008 s. There may be another short pulse (~ 10 ms) at ~ T-2.76 s, which has an image significance of ~ 5.1 sigma in 15-25 keV. T90 (15-350 keV) is ~0.008 sec (due to the extremely short duration, standard bayesian block analysis does not produce a meaningful uncertainty). The time-averaged spectrum from T+0.00 to T+0.008 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.22 +- 0.47. The fluence in the 15-150 keV band is 7.8 +- 2.5 x 10^-9 erg/cm2. The 1-sec peak photon flux measured from T+0.00 sec in the 15-150 keV band is 17.2 +- 4.8 ph/cm2/sec. A single blackbody fit to the time-averaged spectrum shows the blackbody temperature of 9.3 +- 2.1 keV (chi squared 28.52 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. The spectral and temporal properties are more consistent with an SGR, instead of a short GRB. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/999571/BA/