KEPLER_THETA
Maximum angle (in degree) from the disk projected major axis beyond
which the spectra are not considered in the averaging process.
This angle is needed because the projected rotation velocity is degenerate
to zero along the minor axis, which results in a lower effective angular
resolution in this direction. This effect depends on the disk inclination: a
larger angle can be used for less inclined disks.
The default is 60 degree. The Azimut coverage can be visualized using com-
mand SHOW KEPLER_VELO.