Gamma-ray Burst 090815C

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #9824
  J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), P.A. Evans (U. Leicester) on behalf of the Swift Team:
  At 23:21:39 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 090815C (trigger=360068). No GCN Notices were issued because the trigger was below the normal acceptance level. Also, the spacecraft did not execute an automated slew to the location because of an Earth observing constraint. Later, ground-processing using the full data set T-60 to T+303 sec determined the location to be RA, Dec = 64.490, -65.943 deg, which is

     RA(J2000)  =  04h 17m 57.6s
     Dec(J2000) = -65d 56' 33.5"
  

  with an uncertainty of 2.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 76%.
  The BAT mask-weighted light curve shows a single weak peak. T90 (15-350 keV) is 0.6 +- 0.3 sec (estimated error including systematics).
  The time-averaged spectrum from T-0.0 to T+0.7 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 0.90 +- 0.47. The fluence in the 15-150 keV band is 4.4 +- 1.2 x 10^-8 erg/cm2. The 1-sec peak photon flux measured from T-0.18 sec in the 15-150 keV band is 0.6 +- 0.2 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/360068/BA/
  Based on the ground-processing of the full BAT data, a ToO was executed 6.1 hours after the trigger. Swift-XRT obtained 4.3 ks of Photon Counting (PC) mode data, from T0+22 ks to T0+56 ks. No source is found in the BAT error circle, with a 3-sigma upper limit of 1.9 x 10^-3 ct/sec; for a typical GRB, this corresponds to an upper limit on the observed 0.3-10 keV flux of 7 x 10^-14 erg cm^-2 s^-1.