////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  22247
SUBJECT: GRB 171212B: Fermi-LAT detection
DATE:    17/12/12 22:00:25 GMT
FROM:    Giacomo Vianello at SLAC  <giacomov@slac.stanford.edu>

D. Kocevski (NASA/MSFC), F. Longo (Univ & INFN Trieste), E. Bissaldi
(Politecnico & INFN Bari), and G. Vianello (Stanford)

report on behalf of the Fermi-LAT team:

At 10:24:18.51 UT on December 12, 2017, Fermi-LAT detected
high-energy emission from GRB 171212B, which was also detected by
Fermi-GBM (trigger 534767063 / 171212434).

The best LAT on-ground location is found to be

RA, Dec = 39.44, -70.62 (J2000)

with an error radius of 0.39 deg
(90 % containment, statistical error only).

This was 11 deg from the LAT boresight at the time of the trigger.

The data from the Fermi-LAT show a significant increase in the event rate
that is spatially correlated with the trigger with high significance.
The highest-energy photon is a 931 MeV event which
is observed 544 seconds after the GBM trigger.

The Fermi-LAT point of contact for this burst is
Francesco Longo (francesco.longo@ts.infn.it).

The Fermi-LAT is a pair conversion telescope designed to cover
the energy band from 20 MeV to greater than 300 GeV.
It is the product of an international collaboration between
NASA and DOE in the U.S. and many scientific
institutions across France, Italy, Japan and Sweden.

////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  22249
SUBJECT: GRB 171212B: Fermi GBM observation
DATE:    17/12/12 22:51:03 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>

E. Bissaldi (Politecnico & INFN Bari) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:


"At 10:24:18.51 UT on 12 December 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 171212B (trigger 534767063 / 171212434),
which was also detected by the Fermi-LAT (Kocevski et al. 2012, GCN 22247).
The GBM on-ground location is consistent with the LAT position.

The angle from the Fermi LAT boresight at the GBM trigger time is 11 degrees.

The GBM light curve consists of a multipeak emission episode
with a duration (T90) of about 32 s (50-300 keV).
The time-averaged spectrum from T0 to T0+32 s is
adequately fit by a Band function with Epeak = 74 +/- 9 keV,
alpha = -0.95 +/- 0.13, and beta = -2.32 +/- 0.15.

The event fluence (10-1000 keV) in this time interval is
(5.744 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+27 s in the 10-1000 keV band
is 5.0 +/- 0.3 ph/s/cm^2.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."