LBA observations for project V652 semester 2024APRS

Relativistic outflows from cosmic explosions are some of the most extreme environments in the Universe, providing a natural laboratory to study the physics of jets, radiative transfer theory, and to uncover the nature of the explosions and their progenitors. The outflows from cosmic explosions -- from gamma-ray bursts (GRBs) to core-collapse supernovae (CCSNe), fast blue optical transients (FBOTs), and tidal disruption events (TDEs) -- have primarily been studied through modelling multi-wavelength photometry and spectra. However, such an approach is often limited by degeneracies intrinsic to the models (and limited number of observables). Very Long Baseline Interferometry (VLBI) offers valuable, complementary insight into these systems. The ${\sim}$mas angular resolution achievable with VLBI allows direct measurements (or constraints) on the source size, structure, geometry and evolution (expansion or proper motion), independent of multi-wavelength modelling. This in turn sheds light onto the role relativistic outflows play in these cosmic explosions, revealing insights into the spectrum of ejecta velocities, universality in the physics of relativistic outflow between different systems, and consequentially, the nature of the system progenitors.