[vsnet-grb-info 24500] GRB 191227A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26599
SUBJECT: GRB 191227A: Fermi GBM detection
DATE:    19/12/27 22:44:34 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076 at uah.edu>

S.Poolakkil(UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 01:39:24.72 UT on 27 December 2019, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 191227A(trigger 599103569 / 191227069),
which was also detected by the Swift/BAT (Melandri et al. 2019, GCN 26595)
and Fermi LAT (Fana Dirirsa et al. 2019, GCN 26598).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 96
degrees.

The GBM light curve consists of multiple overlapping pulses
with a duration (T90) of about 25 s (50-300 keV).
The time-averaged spectrum from T0+8.19 s to T0+37.88 s is
best fit by a Band function with Epeak = 362 +/- 10 keV,
alpha = -0.93 +/- 0.01 and beta = -2.36 +/- 0.07.

The event fluence (10-1000 keV) in this time interval is
(7.30 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux
measured starting from T0+15.8 s in the 10-1000 keV band
is 38.0 +/- 0.5 ph/s/cm^2.

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/"