GRB 221206B

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

At 12:22:47 UT on 6 Dec 2022, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 221206B (trigger 692022172.359134 / 221206516).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 255.1, Dec = 44.5 (J2000 degrees, equivalent to J2000 17h 00m, 44d 30'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 129.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221206516/quicklook/glg_skymap_all_bn221206516.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/bn221206516/quicklook/glg_healpix_all_bn221206516.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221206516/quicklook/glg_lc_medres34_bn221206516.gif

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a ToO observation of the Swift/BAT-GUANO GRB 221206B. 
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021532

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Swift/BAT-GUANO event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a 
GCN Circular after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.

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

Swift/BAT did not trigger on GRB 221206 (T0: 2022-12-06T12:22:47
UTC, Fermi/GBM GCN 33023
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 ).

The Fermi/GBM 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 burst is detected in BAT with a duration of ~12 seconds.
The burst occurred during a Swift slew.
A candidate location for the burst was found with an SNR of 6.6.

The BAT position is
RA, Dec = 251.155, +42.671 deg which is
   RA(J2000)  = 16h 44m 37.13s
   Dec(J2000) =  +42d 40��� 17.0���
with an estimated uncertainty of 4 arcmin.

This position is consistent with the Ferm/GBM localization (GCN 33023
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 ).
XRT and UVOT follow-up has been requested. Results of follow-up
observations will be reported in future circulars.

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), N. Husarikova, F. Munz , M. Topinka, M. Kolar, J.-P. Breuer, 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 (Os
 aka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration.

The long-duration GRB 221206B (Fermi/GBM detection: GCN Circ. 33023
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 ; Swift/BAT-GUANO detection: GCN Circ. 33027
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 ; Konus/Wind detection, trigger time at 2022-12-06 12:22:46.185 UT; INTEGRAL/SPI-ACS detection, peak time at ~2022-12-06 12:22:49 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. Proc. SPIE 2020).

The detection was confirmed at the peak time 2022-12-06 12:22:49 UTC. The light curve observed by GRBAlpha shows a double-peak structure with a T90 duration of 8 s. The SNR during T90 reaches 36.

The light curve obtained by GRBAlpha is available here:
https://grbalpha.konkoly.hu/static/share/GRB221206B_GCN.pdf

GRBAlpha is a demonstration mission for a future CubeSats constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. GRBAlpha was launched on 2021 March 22 from Baikonur. After its commissioning phase, the scientific observations are now under way. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume.

J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), P. D'Avanzo
(INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi  (INAF-IASFPA) ,
D.N. Burrows (PSU), J. D. Gropp (PSU), S. Dichiara (PSU), A.P.
Beardmore (U. Leicester) and P.A. Evans (U. Leicester) report on behalf
of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Swift/BAT-GUANO-detected burst GRB 221206B, collecting 4.8 ks of Photon
Counting (PC) mode data between T0+28.7 ks and T0+45.0 ks. 

No X-ray sources have been detected within the Swift/BAT-GUANO error
circle. The 3-sigma upper limit in the field ranges from ~0.002 to
~0.003 ct s^-1, corresponding to a 0.3-10 keV observed flux of 7.7e-14
to 1.0e-13 erg cm^-2 s^-1 (assuming a typical GRB spectrum).

Five uncatalogued sources were detected too far from the GRB position
to be likely afterglow candidates.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021532.

This circular is an official product of the Swift-XRT team.

C. Malacaria (ISSI) and C. Meegan (UAH) report on behalf of the Fermi 
GBM Team: "At 12:22:47.36 UT on 06 December 2022, the Fermi Gamma-Ray 
Burst Monitor (GBM) triggered and located GRB 221206B (trigger 692022172 
/ 221206516). The GBM Final Real-time Localization was reported in GCN 
33023
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 . The event was also detected by the Swift/BAT-GUANO (DeLaunay et 
al. 2022, GCN 33027
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 ) at a consistent position. The angle from the Fermi 
LAT boresight at the GBM trigger time is 121 degrees. The GBM light 
curve consists of two main peaks with a duration (T90) of about 8 s 
(50-300 keV). The time-averaged spectrum from T0-0 s to T0+5.9 s is best 
fit by a Band function with Epeak = 151 +/- 6 keV, alpha = -0.36 +/- 
0.06, and beta = -3.1 +/- 0.2 The event fluence (10-1000 keV) in this 
time interval is (2.19 +/- 0.05)E-06 erg/cm^2. The 1-sec peak photon 
flux measured starting from T0+7.5 s in the 10-1000 keV band is 26.7 +/- 
0.7 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 
<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/ 
<https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/>"