Conventions

Inclination

Disk inclination ranges from 0 to 180 degrees. 0 degrees means face on, angular momentum vector pointing at observer; 90 means edge on; and 180 means face on, angular momentum vector pointing away from observer. These are the same as the RADMC-3D conventions and the typical conventions in the astrometric orbital field: inclination < 90 means counter-clockwise rotation and inclination > 90 means clockwise rotation.

Position Angle

We adopt the RADMC-3D convention for position angle, which defines position angle by the angular momentum vector. A positive PA angle means the disk angular momentum vector will be rotated counter clockwise (from North towards East).

The convention used by DiskJockey and RADMC-3D is 90 degrees offset from the convention frequently used in the orbital field, which defines position angle using the ascending node, $\Omega$. For disks, the ascending node is the redshifted portion of the disk major axis (see Czekala et al. 2019 for a discussion).