I have a bit of a trouble understanding how the angles gamma and psi are calculated in the polarisation part of the continuum source function. My understanding is that gamma is the angle between the magnetic field (B) and the plane of the sky/image, while psi is the position angle of the magnetic field projected into the image plane (i.e. the angle between the direction of North in the image plane and the projected B-vector). The sourceFunc_pol() and stokesangles() functions consistently use a variable name incl to describe the orientation of the model/source. The essence of my question is: how are gamma and psi calculated in the polarisation module and what is the meaning of incl in the source function? From the usage of incl within the functions I'm guessing it should be the inclination angle. However in the raytracer it is image.theta that is passed to the polarisation source function and image.theta is equivalent of the inclination if and only if image.phi is zero. Also why is there only a single angle in the polarisation module to describe the source orientation as, to my understanding, psi depends on the position angle of the source, i.e. to calculate both gamma and psi the source orientation has to be described by two angles.
I have a bit of a trouble understanding how the angles gamma and psi are calculated in the polarisation part of the continuum source function. My understanding is that gamma is the angle between the magnetic field (B) and the plane of the sky/image, while psi is the position angle of the magnetic field projected into the image plane (i.e. the angle between the direction of North in the image plane and the projected B-vector). The
sourceFunc_pol()andstokesangles()functions consistently use a variable nameinclto describe the orientation of the model/source. The essence of my question is: how are gamma and psi calculated in the polarisation module and what is the meaning ofinclin the source function? From the usage ofinclwithin the functions I'm guessing it should be the inclination angle. However in the raytracer it isimage.thetathat is passed to the polarisation source function andimage.thetais equivalent of the inclination if and only ifimage.phiis zero. Also why is there only a single angle in the polarisation module to describe the source orientation as, to my understanding, psi depends on the position angle of the source, i.e. to calculate both gamma and psi the source orientation has to be described by two angles.