TITLE:   GCN CIRCULAR
NUMBER:  33028
SUBJECT: GRB 221206B: Detection by GRBAlpha
DATE:    22/12/07 23:28:51 GMT
FROM:    Marianna Dafcikova at Masaryk University  <500025@mail.muni.cz>

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; Swift/BAT-GUANO detection: GCN Circ. 33027; 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.