Sub-arcsecond IRAM Plateau de Bure mm-interferometric observations of the ^ { 12 } CO ( 2-1 ) line emission in the Seyfert 1 NGC 3227 and the Seyfert 2 NGC 1068 have revealed complex kinematic systems in the inner 100 pc to 300 pc that are not consistent with pure circular motion in the host galaxies .
Modeling of these kinematic systems with elliptical orbits in the plane of the host galaxy ( representing gas motion in a bar potential ) is a possible solution but does not reproduce all features observed .
A better description of the complex kinematics is achieved by circular orbits which are tilted out of the plane of the host galaxy .
This could indicate that the thin circumnuclear gas disk is warped .
In the case of NGC 1068 the warp model suggests that at a radius of \sim 70 pc , the gas disk is oriented edge-on providing material for the obscuration of the AGN nucleus .
The position-velocity diagrams show rising rotation curves at r \leq 13 pc and an indication for large enclosed masses of \geq 2 \times 10 ^ { 7 } M _ { \odot } for NGC 3227 and \geq 10 ^ { 8 } M _ { \odot } for NGC 1068 within the central 25 pc .