H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), E. Troja (NASA/GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 100305A (trigger #414905) (Troja, et al., GCN 10470). The BAT ground-calculated position is RA, Dec = 168.373, 42.381 deg which is RA(J2000) = 11h 13m 29.5s Dec(J2000) = +42d 22' 50.7" with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 22%. The mask-weighted light curve shows a broad structure of two overlapping peaks beginning at T+0 and continuing to T+80 sec with the highest peak at T+60 sec. There is soft, low-level emission extending to ~T+200 sec. T90 (15-350 keV) is 69.7 +- 8.7 sec (estimated error including systematics). The time-averaged spectrum from T-9.2 to T+70.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.27 +- 0.23. The fluence in the 15-150 keV band is 1.5 +- 0.2 x 10^-6 erg/cm^2. The 1-sec peak photon flux measured from T+62.72 sec in the 15-150 keV band is 0.9 +- 0.3 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/414905/BA/

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