# Observation Directions

This option allows the user to set the position of the observation.

• Spherical observation. If the position of the source has been defined in spherical coordinates, this option will be available. It is possible to define a parametric sweep for one variable (radius, theta or phi) selecting the check box Source Position Sweep. The initial value for R, theta and phi have to be specified.
• Final value final value for the chosen variable (R, theta or phi).
• Samples number of samples.
• Cartesian observation. If the position of the source has been defined in Cartesian coordinates, this option will be available. It is possible to define a parametric sweep on t selecting the check box Sweep on 't'. The coordinates x, y and z can be defined with a function which values could depend on the parameter 't'. The initial value for R, theta and phi have to be specified.
• Initial 't' the initial value for t.
• Final 't' the final value for t.
• Samples on 't' number of samples.