TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4873 SUBJECT: GRB 060313: Refined analysis of the Swift-BAT bright short hard burst DATE: 06/03/13 05:43:42 GMT FROM: Scott Barthelmy at NASA/GSFC C. Markwardt (GSFC/UMD), L. Barbier (GSFC), S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), J. Tueller (GSFC) on behalf of the Swift-BAT team: Using the data set from T-60 to T+123 sec from the recent telemetry downlink, we report further analysis of BAT GRB 060313 (trigger #201487) (Pagani, et al., GCN 4867). The BAT ground-calculated position is RA,Dec = 66.624,-10.859 deg {04h 26m 29.8s,-10d 51' 30.9"} (J2000) +- 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 54%. The lightcurve shows 3 or 4 overlapping peaks. They start with a very fast rise (less than 40 msec). There is a possibility of further faint emission past the end of the last peak (T+1 to T+2 sec). T90 (15-350 keV) is 0.7 +- 0.1 sec (estimated error including systematics). The time-averaged spectrum from T+0.06 to T+0.94 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 0.71 +- 0.07. The fluence in the 15-150 keV band is 1.13 +- 0.05 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.01 sec in the 15-150 keV band is 12.1 +- 0.4 ph/cm2/sec. All the quoted errors are at the 90% confidence level.