GCN Circular 32685
Subject
GRB 221009A: Detection by GRBAlpha
Date
2022-10-11T13:24:38Z (2 years ago)
From
Jakub Ripa at Masaryk University <245487@mail.muni.cz>
J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk
U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly
Observatory), M. Dafcikova, 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 Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan)
-- the GRBAlpha collaboration.
The extraordinarily bright long-duration GRB 221009A (Swift/BAT
detection: Kennea et al., GCN 32635; Fermi-GBM detection: Veres et al.,
GCN 32636; Fermi-LAT detection: Pillera et al., GCN 32658; INTEGRAL
SPI/ACS detection: Gotz et al., GCN 32660; Konus-Wind detection:
Frederiks et al., GCN 32668; IPN triangulation: Svinkin et al., GCN
32641; LHAASO detection: Huang et al., GCN 32677) at a redshift of z =
0.151 (de Ugarte Postigo et al., GCN 32648) was detected by the GRBAlpha
1U CubeSat (Pal et al. Proc. SPIE 2020).
The GRB did not saturate our detector and the peak count rate reached
~22 000 count/s in the ~70-890 keV energy band (for a 50 cm^2 detector)
at 2022-10-09 13:20:52 UTC. The duration of the GRB was >250s. GRBAlpha
was flying above the northern polar region with elevated background
levels. The end part of the GRB was recorded while passing the outer Van
Allen radiation belt.
The light curve obtained by GRBAlpha is available here:
https://grbalpha.konkoly.hu/static/share/GRB221009A_GCN_GRBAlpha.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.