GCN Circular 39291
Subject
GRB 250207A: Fermi GBM Observation
Event
Date
2025-02-11T21:31:46Z (a year ago)
From
oindabimukherjee@gmail.com
Via
Web form
O. Mukherjee (USRA), R. Hamburg (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 01:16:03.15 UT on 07 February 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 250207A (trigger 760583768/250207053).
which was also detected by Swift BAT (Ferro et al. 2025, GCN 39182), COLIBRÍ/DDRAGO (Angulo et al. 2025, GCN 39186),
Swift/UVOT (Kuin et al. 2025, GCN 39199), and Konus-Wind (Ridnaia. et al. 2025, GCN 39284)
The Fermi GBM Final Real-time Localization (GCN 39181) is consistent with the Swift BAT position.
The angle from the Fermi LAT boresight is 46 degrees.
The GBM light curve consistes of a single emission episode with multiple peaks with a duration (T90)
of about 20 s (50-300 keV). The time-averaged spectrum
from T0-3.1 to T0+25.6 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.10 +/- 0.06 and the cutoff energy,
parameterized as Epeak, is 290 +/- 30 keV.
The event fluence (10-1000 keV) in this time interval is
(1.04 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+12 s in the 10-1000 keV band is 4.7 +/- 0.3 ph/s/cm^2.
A Band function fits the spectrum equally well
with Epeak= 240 +/- 30 keV, alpha = -1.03 +/- 0.08 and beta = -2.3 +/- 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/"