What Is the Accretion Rate in NGC 4258?

We estimate the accretion rate onto the black hole in the nucleus of NGC 4258. The result is model dependent. We find that a thin disk that is flat out to ≳2 × 10 3 GM / c 2 ( M ≡black hole mass) and that has inclination equal to that of the masing disk must have ≃ 0.01 M ☉ yr -1 for consistency with near-infrared data. A thin disk that is warped at ~10 3 GM / c 2 requires ≳ 1.5 × 10 -4 M ☉ yr -1 for consistency with near-infrared data. Reasonable warp models and the near-infrared data are not consistent with as low as the 7 × 10 -5 α M ☉ yr -1 proposed by Neufeld & Maloney. An advection-dominated flow model combined with the X-ray data implies ≃ 0.01 M ☉ yr -1 . Consistency with a tight 22 GHz upper limit on the flux from the central source requires a transition radius of ~(10-100) GM / c 2 , although the 22 GHz upper limit may be relaxed by appeal to free-free absorption. Physical conditions in the observed VLBI jet features can also be related to conditions in the inner accretion flow. We conclude with a list of observations that might further constrain .