GRB 200415A: Fermi GBM observation
Abstract
"At 08:48:05.56 UT on 15 April 2020, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 200415A (trigger 608633290 / 200415367), which was also detected by Fermi-LAT (Omodei et al., GCN 27586). The Fermi GBM Final Real-time Localization (GCN 27579) is consistent with the LAT position. The angle from the Fermi LAT boresight at the GBM trigger time is 49 degrees. The GBM light curve shows a bright single pulse with a duration (T90) of about 0.2 s (50-300 keV). The time-averaged spectrum from T0-0.032 s to T0+0.160 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is 0.07 +/- 0.05 and the cutoff energy, parameterized as Epeak, is 950 +/- 40 keV. The event fluence (10-1000 keV) in this time interval is (5.2 +/- 0.1)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0 in the 10-1000 keV band is 74 +/- 2 ph/s/cm^2. While we report the source to be a possible short GRB, we cannot conclusively rule out a giant magnetar flare of extragalactic origin, as reported by IPN (GCN 27585). Periodicity is not evident in the GBM data. Assuming a distance of 3.5 Mpc and the spectral shape reported above, the isotropic equivalent energy in the 1 keV-10 MeV range is (1.22 +/- 0.03)E+46 erg. Further analysis is ongoing. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
- Publication:
-
GRB Coordinates Network
- Pub Date:
- April 2020
- Bibcode:
- 2020GCN.27587....1B