Polarimetric observations of the masers in NGC 4258: An upper limit on thelarge-scale magnetic field 0.2 Parsecs from the central engine

report VLA 1 sigma upper limits of 1.5% and 3% on the intrinsic circular an d linear fractional polarizations, respectively, of the water vapor maser e mission 0.2 pc from the central engine of NGC 4258. A corresponding 0.5% up per limit on any Zeeman-splitting-induced circular polarization translates to a 1 sigma upper limit on the parallel, or toroidal, component of the mag netic held of 300 mG. Assuming magnetic and thermal pressure balance in the disk, this magnetic field upper limit corresponds to a model-dependent est imate of the accretion rate through the molecular disk of 10(-1.9) alpha M- . yr(-1) for the case where the magnetic held lies along the line of sight.