Supernova remnants are expanding nebulae produced by the explosion of high-mass stars. They are of great interest for understanding various physical processes and the final evolutionary stages of massive stars. Observations of supernova remnants in gamma rays are particularly important as they shed light on high-energy processes, such as the acceleration of cosmic rays (charged particles at very high energies).
Supernove explosions are repeatedly observed in distant galaxies, which lie at such large distances that it is impossible for us to resolve the geometry of the ejected material and its interaction with the surrounding interstellar and circumstellar clouds. With the only exception of SN 1978A, in the Milky Way and in the nearby galaxies (namely the Magellanic Clouds), we did
