TITLE: GCN CIRCULAR NUMBER: 6429 SUBJECT: GRB 070520B, Swift-BAT refined analysis DATE: 07/05/21 00:15:51 GMT FROM: Scott Barthelmy at NASA/GSFC T. Sakamoto (GSFC/ORAU), L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), A. Moretti (INAF-OAB), D. Palmer (LANL), A. Parsons (GSFC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC) on behalf of the Swift-BAT team: Using the data set from T-239 to T+592 sec from recent telemetry downlinks, we report further analysis of BAT GRB 070520B (trigger #279898) (Moretti, et al., GCN Circ. 6245). The BAT ground-calculated position is RA, Dec = 121.886, 57.588 deg which is RA(J2000) = 08h 07m 32.7s Dec(J2000) = 57d 35' 15.3" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 59%. The mask-weighted light curve shows two overlapping peaks starting at T-4 sec, peaking at T+1 sec, and ending with a long tail at T+200 sec. T90 (15-350 keV) is 66 +- 4 sec (estimated error including systematics). The time-averaged spectrum from T-5.0 to T+71.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.15 +- 0.21. The fluence in the 15-150 keV band is 9.2 +- 1.1 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.74 sec in the 15-150 keV band is 0.4 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level.