GCN Circular 32814

J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory),�� N. Werner�� (Masaryk 
U.), M. Ohno (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), 
H. Takahashi (Hiroshima U.), F. Munz, M. Dafcikova, N. Husarikova, M. 
Topinka, F. Hroch, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M. 
Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix 
s.r.o), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida 
(ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. 
Hirose, H. Poon, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. 
Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory),�� T. Mizuno 
(Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. 
Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. 
Gromes (VZLU), I. Vertat (FEL ZCU), T. Urbanec, M. Kasal, A. Povalac 
(Brno U. of Technology), M. Smelko, P. Hanak, P. Lipovsky (Technical U. 
of Kosice), T. Bozoki, G. Dalya, G. Friss, K. Kapas, J. Takatsy (Eotvos 
U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. 
Tokyo), T. Kano (U. Michigan) -- the VZLUSAT-2/GRB payload and GRBAlpha 
collaborations

We report a joint detection of the recently active SGR 1935+2154 by the 
GRB detector on board of VZLUSAT-2 3U CubeSat 
(https://www.vzlusat2.cz/en/) and 1U GRBAlpha CubeSat (Pal et al. Proc. 
SPIE 2020). The bursting activity was also observed by Insight-HXMT (C. 
K. Li et al., ATel #15698), INTEGRAL/SPI-ACS, and�� Konus-Wind (D. 
Svinkin priv. comm.). Non-detection by Fermi/GBM can be explained by the 
Earth occultation of�� SGR 1935+2154 (P. Veres priv. comm.).

The list of distinct peaks measured by the GRB detector module no. 1 on 
board of the VZLUSAT-2 with their background-subtracted peak rates in 
~40-890 keV band and significance is:

Date and time in UTC�������� peak rate (cnt/s)�� �� �� SNR
2022-10-14 17:26:07.5���������������������������������� 220�������� 12.9
2022-10-14 17:27:36.5�������������������������������� 1170�������� 62.6
2022-10-14 17:27:39.5���������������������������������� 931�������� 48.8
2022-10-14 17:27:43.5���������������������������������� 159���������� 8.1
2022-10-14 17:27:49.5���������������������������������� 205�������� 10.0

The light curves obtained by VZLUSAT-2 and GRBAlpha are available here:
https://grbalpha.konkoly.hu/static/share/SGR_1935_2154_GCN_GRBAlpha_VZLUSAT_2.pdf

GRB detectors on VZLUSAT-2 are a demonstration payload for a future 
CubeSats constellation (Werner et al. Proc. SPIE 2018). Two GRB modules 
of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 
75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the 
energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 
January 13 from Cape Canaveral.

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.

We thank P. Veres and D. Svinkin for providing us with information which 
helped us to associate our detection with SGR 1935+2154.