Key points are not available for this paper at this time.
New spectroscopy of M31 supports Tremaine's model in which both nuclei are parts of a single eccentric disk of stars orbiting the black hole (BH). The kinematics and Hubble Space Telescope photometry are used to measure the offset of the BH from the center of mass. This confirms that the BH mass is ~ 3 × 107 M☉ by a technique that is nearly independent of stellar-dynamical models.
Kormendy et al. (Fri,) studied this question.