TITLE: GCN CIRCULAR NUMBER: 32904 SUBJECT: GRB 221028A: Detection by VZLUSAT-2 DATE: 22/11/01 18:05:11 GMT FROM: Jakub Ripa at Masaryk University 245487@mail.muni.cz
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. Topinka, F. Hroch, M. Dafcikova, N. Husarikova, J.-P. Breuer (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 long-duration GRB 221028A (Swift/BAT detection: Lien et al., GCN Circ. 32874; AGILE detection: Ursi et al., GCN Circ. 32885; KONUS-Wind detection: trig. time 2022-10-28 13:16:29.550 UT; INTEGRAL/SPI-ACS detection peak at 2022-10-28 13:16:28.3 UT) was detected by both GRB detector units on board of the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/).
The data acquisition was performed by GRB detector units no. 0 and no. 1. The 7.1 (6.1) sigma detection significance was confirmed at detector unit no. 0 (no. 1) at 2022-10-28 13:16:26 UTC. The T90 duration was measured to be 23 s (26 s) for detector unit no. 0 (no. 1).
The light curve obtained by VZLUSAT-2 is available here: https://vzlusat2.konkoly.hu/static/share/GRB221028A_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.