The workstation screen in the above photo shows an unsharp-masked spectrum of the Sombrero Galaxy (NGC 4594) and the rotation curve implied by the S-shaped spectral lines. This rapid rotation and the observed steep velocity dispersion gradient are the signature of a billion-solar-mass black hole (see Kormendy et al. 1996, ApJL, 473, L91 in Recent papers and preprints and references therein).

John Kormendy (