Gamma-ray Burst 140901B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #16773
  J. R. Cummings reports on behalf of the Swift science team:
  At 06:17:24 Swift-BAT rate-triggered on GRB 140901B (trigger # 611389). Fermi-GBM also triggered on this event (trigger 431245045). No source was found onboard. In ground analysis, a significant source was found at RA, Dec 112.184, -29.209, which is

      RA (J2000)   07h 28m 44.2s 
      Dec (J2000) -29d 12' 31"
  

  with an estimated 90% uncertainty radius of 2.0 arcmin. This location is 3.0 degrees from the reported GBM location (http://gcn.gsfc.nasa.gov/other/431245045.fermi), within the GBM error circle.
  The background in BAT was high, since Swift was near the SAA. The BAT lightcurve shows a single FRED peak, with T90 about 10 +- 1 sec.
  The BAT spectrum with 10.0 seconds of data is best fit by a simple power- law function with a photon index of 1.20 +- 0.22. Using this model, the fluence was (9.5 +- 1.3) x 10^-7 ergs/cm^2. Errors are 90% confidence.
  A Swift TOO request has been submitted, but this burst is already 3.5 days old, and moreover is rather close to the Sun.
• GCN Circular #16775
  Bin-Bin Zhang (UAH) reports on behalf of the Fermi GBM Team:
  "At 06:17:22.79 UT on 01 September 2014, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 140901B (trigger 431245045 / 140901262), which was also detected by the Swift/BAT (Cummings 2014, GCN 16773) The GBM on-ground location is consistent with the Swift position.
  The angle from the Fermi LAT boresight is 34 degrees.
  The GBM light curve consists of a single pulse with a duration (T90) of about 65 +/- 14 s (50-300 keV). The time-averaged spectrum from T0-0 s to T0+65 s is best fit by a power law function with an exponential high-energy cutoff. =C2=A0The power law index is -1.2 +/- 0.2 =C2=A0and the cutoff energy, parameterized as Epeak, is 219 +/- 82 keV.
  The event fluence (10-1000 keV) in this time interval is (3.8 +/- 0.6)E-06 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+0.9 s in the 10-1000 keV band is 2.6 +/- 0.2 =C2=A0ph/s/cm^2.
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
• GCN Circular #16782
  V. D'Elia (ASDC), L. Izzo (URoma/ICRA) and A. Maselli (INAF-IASFPA) report on behalf of the Swift-XRT team:
  XRT began a target of opportunity observation of GRB140901B, detected by Swift-BAT (Cummings, GCN Circ. 16773) and Fermi-GBM (Zhang, Circ. 16775). Swift slewed to the burst on 2014-09-05.
  Observations with the XRT began at 01:23:58 UT, i.e., 330 ks after the trigger, and comprised a total of 2.97 ks in photon counting mode.
  We do not detect any X-ray sources, within the BAT error circle (Cummings, GCN Circ. 16773), with S/N>2. We place a 3-sigma upper limit on the count rate at the BAT position of 3.85E-03 cts/s.
  This circular is an official product of the Swift-XRT team.