GCN Circular 36949
Subject
GRB 240727B: Fermi GBM Observation
Date
2024-07-27T19:00:39Z (4 months ago)
From
Cori Fletcher at USRA <cfletcher@usra.edu>
Via
Web form
C. Fletcher (USRA), R. Hamburg (CNRS/IJCLab) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 06:00:08.96 UT on 27 July 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240727B (trigger 743752813/240727250).
which was also detected by Swift/BAT-GUANO (Ronchini et al. 2024, GCN 36945) and AstroSat (Waratkar et al. 2024, GCN 36943).
The Fermi GBM on-ground location is consistent with the Swift/BAT-GUANO position.
The angle from the Fermi LAT boresight is 114 degrees.
The GBM light curve consists of multiple peaks with a duration (T90)
of about 19 s (50-300 keV). The time-averaged spectrum
from T0-3.3 to T0+20.2 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.3 +/- 0.1 and the cutoff energy,
parameterized as Epeak, is 850 +/- 90 keV.
The event fluence (10-1000 keV) in this time interval is
(1.52 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+8.7 s in the 10-1000 keV band is 3.4 +/- 0.4 ph/s/cm^2.
A Band function fits the spectrum equally well
with Epeak= 848 +/- 116 keV, alpha = -0.3 +/- 0.1 and beta = -2.5 +/- 0.3.
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/"