M77

M77 (also called Cetus A) is a barred spiral galaxy in Cetus, about 47 million light-years from Earth. It is one of the largest Messier galaxies, spanning about 170,000 light-years. M77 harbors one of the brightest and most active Seyfert nuclei known — its supermassive black hole (about 15 million solar masses) actively accretes material and powers intense radiation across the electromagnetic spectrum.

Located about 1 degree east-southeast of Delta Ceti. In a telescope it appears as a bright, round, concentrated glow dominated by the brilliant nucleus. The spiral arms have low surface brightness and require 10 inches or more to detect. The intense nuclear brightness makes it easy to spot but hard to see detail. Best observed from October through January.

Discovered by Pierre Mechain on October 29, 1780. Charles Messier cataloged it on December 17, 1780. It was one of the first galaxies identified as having an active nucleus — Carl Seyfert included it in his 1943 study of galaxies with unusually bright cores, which defined the class of Seyfert galaxies.