////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  31763
SUBJECT: GRB 220317A: Fermi GBM Final Real-time Localization
DATE:    22/03/17 12:58:50 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 12:48:30 UT on 17 Mar 2022, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 220317A (trigger 669214115.664266 / 220317534).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 172.0, Dec = -11.3 (J2000 degrees, equivalent to J2000 11h 28m, -11d 18'), with a statistical uncertainty of 13.3 degrees.

The angle from the Fermi LAT boresight is 48.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220317534/quicklook/glg_skymap_all_bn220317534.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220317534/quicklook/glg_healpix_all_bn220317534.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220317534/quicklook/glg_lc_medres34_bn220317534.gif

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TITLE:   GCN CIRCULAR
NUMBER:  31766
SUBJECT: GRB 220317A: Swift/BAT-GUANO detection outside the coded FOV
DATE:    22/03/18 15:15:50 GMT
FROM:    Aaron Tohuvavohu at U Toronto  <aaron.tohu@gmail.com>

Aaron Tohuvavohu (U Toronto), James DeLaunay (UAlabama), Gayathri
Raman (PSU), Jamie A. Kennea (PSU), report:

Swift/BAT did not localize GRB 220317A onboard (T0:
2022-03-17T12:48:30 UTC, Fermi/GBM GCN 31763).

The Fermi notice, distributed in near real-time, triggered the Swift
Mission Operations Center operated Gamma-ray Urgent Archiver for Novel
Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).

Upon trigger by this notice, GUANO sent a command to the Swift Burst
Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from
[-50,+150] seconds around the time of the burst. All the requested
event mode data was delivered to the ground.

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu,
arXiv:2111.01769), detects the burst with a sqrt(TS) of 10.2 in a
8.192 s analysis time bin.

NITRATES results are consistent with a burst coming from outside the
coded FoV, as indicated by the Fermi/GBM localization (GCN 31763).

See Section 9.1 and Figure 20 in the NITRATES paper for brief
descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and
DeltaLLHOut.

GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.

A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/

////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  31778
SUBJECT: GRB 220317A: Fermi GBM detection
DATE:    22/03/21 16:46:18 GMT
FROM:    Rachel Hamburg at UAH  <rkh0007@uah.edu>

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

"At 12:48:30.66 UT on 17 March 2022, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 220317A (trigger 669214115 / 220317534).
which was also detected by the Swift/BAT-GUANO (Tohuvavohu et al. 2022, GCN
31766).

The angle from the Fermi LAT boresight at the GBM trigger time is 48
degrees.

The GBM light curve shows two peaks with a duration (T90)
of about 14 s (50-300 keV). The time-averaged spectrum
from T0-6.1 s to T0+8.2 s is best fit by a power law
function with an exponential high-energy cutoff.
The power law index is -1.1 +/- 0.2 and the cutoff
energy, parameterized as Epeak, is 248 +/- 96 keV.

The event fluence (10-1000 keV) in this time interval is
(1.2 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.4 s in the 10-1000 keV band
is 1.6 +/- 0.2 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/"