SN 1990U

SN 1990U was a supernova discovered in 1990. Its designation follows the standard supernova naming convention: "SN" denotes "supernova," the following four digits indicate the year of discovery (1990), and the final letter represents the order of discovery within that year. In this case, "U" means it was the 21st supernova discovered in 1990, following the sequence A, B, C, and so on (excluding I, as well as duplicates).

Specific details about SN 1990U, such as its type (e.g., Type Ia, Type II), host galaxy, precise location, light curve, and spectral characteristics, would require consulting supernova catalogs, astronomical databases (like SIMBAD or the NASA/IPAC Extragalactic Database (NED)), and published research papers. The amount of publicly available information varies depending on the supernova and the level of subsequent study it received.