Use this option only together with mc_panorama_view. This option has been introduced to facilitate e.g. the calculation of circum solar radiation. Three sub-options are available, sun, mu, and zenith. When set sun, the camera is aligned to sun (i.e. using the options sza and phi0). \theta and \mu as given by the option mc_panorama_view now relates to the sun's position. \mu sets cosine of the angular distance from the center of the sun. \mu=-1 implies looking directly into the sun. With \phi we select the direction around the sun on a circle with angular distance {\rm acos}(\mu) from the center of the sun. \phi=0 implies that the camera pixel is looking in a direction exactly below the sun, at \phi=180 the camera pixel will be looking exactly above the sun. Increasing \phi means the direction of looking moves clock-wise around the sun-camera-line (seen from the sun). If the sun is in the zenith, the definition of \phi is identical to that in phi.

The sub-option mu aligns the camera geometry according to the options umu and phi. Be aware that phi0 and phi are defined differently!

The sub-option zenith makes only sense when using mc_spherical 3D. Then the camera is aligned to the zenith with respect to the lon-lat position of the camera.