Abstract:

I will present results from three CubeSats (GRBAlpha, GRBBeta,
VZLUSAT-2), which have the main goal to detect gamma-ray bursts (GRBs).
In these projects, Masaryk University has a strong involvement in the
development, operation and science case of these CubeSats. Furthermore,
I will present the status and the science case of the small satellite
mission Quick Ultra-Violet Kilonova surveyor (QUVIK). GRBAlpha was a 1U
CubeSat launched in 2021 to a low Earth orbit (LEO) and successfully
operated for more than 4 years until 2025. VZLUSAT-2 was a 3U CubeSat
launched in 2022, and it operated on LEO for almost 4 years until the
end of 2025. Both missions have detected about 360 gamma-ray transients,
including over 180 long and short GRBs, including the most intense GRB
ever recorded, GRB 221009A and the second brightest GRB 230307A.
GRBBeta, the 2U CubeSat, was integrated at Masaryk University and
launched in 2024, and its mission continues successfully detecting GRBs.
Gamma-ray detectors on these CubeSats are based on CsI(Tl) scintillator
readout by silicon photomultipliers (SiPMs), thereby providing a unique
opportunity to study in-orbit radiation damage of SiPMs. We have
demonstrated that SiPMs can be used in the low Earth environment on a
scientific mission lasting beyond 4 years and that CubeSats can be
utilised for routine detection of GRBs. QUVIK will be an ultra-violet
(UV) space telescope on a small satellite with a mass of approximately
200 kg, featuring moderately fast re-pointing and a real-time alert
communication system, approved for a Czech national space mission. The
satellite, expected to launch in 2030, will provide key follow-up
capabilities to enhance the discovery potential of gravitational wave
observatories and future wide-field multi-wavelength surveys. The
primary objective of the mission is to measure the UV brightness
evolution of kilonovae resulting from neutron star mergers. The mission,
designed to complement ULTRASAT, will also provide unique follow-up
capabilities for other transients in the near- and far-UV bands. These
will include UV counterparts of gamma-ray bursts (GRBs), supernovae,
novae, transients in active galactic nuclei (AGN), such as the tidal
disruption of stars by supermassive black holes at the centres of
galaxies, UV emissions from stars and stellar systems, including stars
hosting exoplanets.