TITLE: GCN CIRCULAR NUMBER: 10528 SUBJECT: Swift-BAT refined analysis of the probable new SGR 1833-0832 DATE: 10/03/19 22:55:16 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), T. Sakamoto (GSFC/UMBC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), J. M. Gelbord (PSU), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+303 sec from the recent telemetry downlink, we report further analysis of BAT trigger #416485 (Gelbord, et al., GCN Circ. 10526). The BAT ground-calculated position is RA, Dec = 278.446, -8.533 deg, which is RA(J2000) = 18h 33m 47.1s Dec(J2000) = -08d 32' 00.2" with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 87%. The mask-weighted light curve shows two resolved peaks with a total duration of ~16 millisec. T90 (15-350 keV) is 0.012 +- 0.009 sec (estimated error including systematics). The time-averaged spectrum from T+0.000 to T+0.016 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index -1.02 +- 1.35, and Epeak of 38.2 +- 5.0 keV (chi squared 43.5 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.3 +- 0.2 x 10^-8 erg/cm2 and the 1-sec peak flux measured from T-0.49 sec in the 15-150 keV band is 0.2 +- 0.1 ph/cm2/sec. Similarly, a blackbody fit yields kT= 10.0 +-1.2 keV (chi squared 43.8 for 57 d.o.f). A fit to a simple power law gives a photon index of 2.58 +- 0.23 (chi squared 74.2 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/416485/BA/ Given (a) the low galactic lattitude (0.01 deg), (b) the short duration of the event, and (c) the spectral softness (Epeak=38.2 and photon index of -1.02), we believe this to be an event from a new probable SGR which we are calling SGR 1833-0832.