Tags: Galaxy.
Markarian 501 (or Mrk 501) is a galaxy with a spectrum extending to the highest energy gamma rays. It is a blazar or BL Lac object which is an active galactic nucleus with a jet that is shooting towards the earth. It is the brightest object in the sky when observed using very high energy gamma rays at energies above 0.1 Teraelectronvolt (TeV) (1011 eV). The object has a redshift of z = 0.034. The galaxy hosting the blazar was studied and catalogued by Benjamin Markarian in 1989.