NGC 4395 was imaged and classified as a "spiral nebula" in a 1920 paper by astronomer Francis G. Pease. Now, it is known to be a galaxy distinct from the Milky Way (see Great Debate). Along with several other nearby galaxies, resolved stars in NGC 4395 were used to measure the expansion rate of the Universe by Allan Sandage and Gustav Andreas Tammann in their 1974 paper. More recently, NGC 4395 was discovered to contain a very low-luminosity active galactic nucleus. Since then, its nucleus has been the subject of several academic papers and attempts to measure the mass of its central black hole.