GCN Circular 31937

J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), M. Ohno (Eotvos 
U./Hiroshima U.),�� N. Werner�� (Masaryk U.),�� L. Meszaros (Konkoly 
Observatory), H. Takahashi (Hiroshima U.), B. Csak (Konkoly 
Observatory), M. Topinka, F. Munz, F. Hroch (Masaryk U.), J. Hudec, J. 
Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), 
G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), 
T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, 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)�� -- the VZLUSAT-2/GRB payload collaboration.

A GRB detected by GECAM (trigger at 2022-04-21 21:03:20.6 observation ID 
00035461090, https://www.swift.psu.edu/guano/) was also detected by both 
GRB detector units on board of the VZLUSAT-2 3U CubeSat 
(https://www.vzlusat2.cz/en/). Note that the reported GECAM trigger is 
~15s earlier than the onset of the GRB seen by VZLUSAT-2.

The data acquisition was performed by GRB detector units no. 0 and no. 
1. The 38 sigma detection significance was confirmed at 2022-04-21 
21:03:47 UTC. The long-duration GRB has the T90 duration of 62 s.

The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB220421B_GCN_VZLUSAT2.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.