NGC 6251 is a giant elliptical galaxy located approximately 250 million light-years away in the constellation Pegasus. It is notable for its active nucleus, which contains a supermassive black hole that emits powerful jets of energy, making it a strong source of radio waves. The galaxy is part of a larger group of galaxies known as the NGC 6251 group. It has a diameter of about 150,000 light-years and is surrounded by a significant amount of hot gas, which contributes to its X-ray emissions. Observations of NGC 6251 help astronomers understand the behavior of galaxies with active galactic nuclei.