GRB 221107A

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

At 01:22:52.46 UT on 7 Nov 2022, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 221107A (trigger 689476977 / 221107058).

The on-ground calculated location, using the Fermi GBM trigger data, is RA
= 146.15, Dec = -45.40 (J2000 degrees, equivalent to J2000 09h 45m, -45d
24'), with a statistical uncertainty of 2.06 degrees.

The angle from the Fermi LAT boresight is 54 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221107058/quicklook/glg_skymap_all_bn221107058.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/bn221107058/quicklook/glg_healpix_all_bn221107058.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221107058/quicklook/glg_lc_medres34_bn221107058.gif

Gayathri Raman (PSU), James DeLaunay (UAlabama), Aaron Tohuvavohu (U
Toronto), Jamie A. Kennea (PSU), Tyler Parsotan (GSFC/UMBC) report:

Swift/BAT did not localize GRB 221107A onboard (T0:
2022-11-07T01:22:54.55 UTC, GECAM trig 53, Fermi/GBM trig 689476977).

The GECAM and Fermi notices, 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
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 ), detects the burst with a sqrt(TS) of 23.8 in a
8.192 s analysis time bin.

NITRATES results indicate a burst coming from outside the FOV, with
DeltaLLHOut of -45.6.
The NITRATES best fit sky location is consistent with the Fermi/GBM
localization (GCN 32193
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 ).

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/

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), F. Munz, N. Husarikova, J.-P. Breuer, M. Topinka, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal,  A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropo
 litan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration.

The long-duration GRB 221107A (Fermi/GBM detection: GCN Circ. 32913
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 , Swift/BAT detection: GCN Circ. 32915
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 ) was detected by the GRBAlpha 1U CubeSat (Pal et al. Proc. SPIE 2020).

The 9.3 sigma detection was confirmed at the peak time 2022-11-07 01:22:58.2 UTC. The light curve shows a double-peak structure with a T90 duration of 265 s.

The light curve obtained by GRBAlpha is available here:
https://grbalpha.konkoly.hu/static/share/GRB221107A_GCN.pdf

GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). Its detector consists of a 75 x 75 x 5 mm^3 CsI(Tl) scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, we are continuously upgrading the on-board data acquisition software stack. The ground segment is also supported by the radio amateur community, and it takes advantage of the SatNOGS network for increased data downlink volume.

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

"At 01:22:52.46 UT on 07 November 2022, the Fermi Gamma-ray Burst Monitor
(GBM) triggered and located GRB 221107A (trigger 689476977 / 221107058.
This event was also observed by Swift/BAT-GUANO (GCN 32915
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 ) and GRBAlpha
(GCN 32917
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 ).

The GBM position is reported in the Fermi-GBM Final on-ground Localization
(GCN 32913
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 ). The angle from the Fermi LAT boresight is 54 degrees.

The GBM light curve shows numerous peaks with a duration (T90) of about 231
s (50-300 keV). The time-averaged spectrum from T0-2 to T0+235 s is best
fit by a Band function with Epeak = 47 +/- 2 keV, alpha = 0.32 +/- 0.17,
and beta = -2.00 +/- 0.02.

The event fluence (10-1000 keV) in this time interval is (7.464 +/-
0.261)E-05 erg/cm2. The 1-sec peak photon flux measured starting from
T0+9.5 s in the 10-1000 keV band is 10.3 +/- 0.4 ph/s/cm2.

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/"