:py:mod:`pytmosph3r.planetary_system.observer`
==============================================

.. py:module:: pytmosph3r.planetary_system.observer


Module Contents
---------------

.. py:class:: Observer(latitude: Union[float, astropy.units.Quantity[pytmosph3r.util.pt.angle]] = None, longitude: Union[float, astropy.units.Quantity[pytmosph3r.util.pt.angle]] = None, orbit=None, **kwargs)


   Bases: :py:obj:`pytmosph3r.log.Logger`

   Defines the position of the observer using a unit vector.
   The starting point of the vector is the center of the planet.
   The ending point is located at the coordinate (:py:attr:`latitude`, :py:attr:`longitude`) on the unit sphere.
   Astropy's units are supported. Floats are considered to be in SI units.
   WARNING: This class has been extracted from :class:`~.rays.Rays` and should probably not be used independently.

   Set the observer's position with:

   :param latitude: Latitude (in :math:`rad` or astropy units). Default to 0.
   :type latitude: float, Unit, optional
   :param longitude: Longitude (in :math:`rad` or astropy units). Default to $\pi$.
   :type longitude: float, Unit, optional

   .. py:property:: coordinates

      Tuple (latitude, longitude).

   .. py:property:: orbit


   .. py:property:: cartesian_system

      Cartesian coordinate system (x,y,z) of which:

      - z is oriented along the rotation axis (pointing towards the North Pole)
      - x points towards a reference point on the equator that corresponds to a longitude equal to zero
      - y is chosen to have a direct basis.

      The coordinates of the unit vector defining the direction of the rays are then computed through
      :class:`~pytmosph3r.util.geometry.CartesianCoordinateSystem` using its spherical coordinates (
      :py:attr:`latitude`, :py:attr:`longitude`).

   .. py:attribute:: latitude

      Latitude coordinate of the ending point of the unit vector (in radians).

   .. py:attribute:: longitude

      Longitude coordinate of the ending point of the unit vector (in radians).

   .. py:method:: build(model=None)

      Link to model, and set default values if not set before.


   .. py:method:: add_ray_origin(altitude, angle)

      Function to add the origin point of a ray, i.e., its intersection with the terminator using its polar
      coordinates (:py:attr:`altitude`, :py:attr:`angle`), to the Cartesian coordinate system
      :py:attr:`cartesian_system`.

      This function is used for each ray in :class:`Rays.compute_sub_rays`.

      :param altitude: altitude (`m`) of the origin point
      :type altitude: float
      :param angle: angle (`radians`) of the origin point
      :type angle: float


   .. py:method:: position_from_time(time, orbit=None)

      Update the position of the observer based on the time (in :math:`seconds`) and the orbit.



   .. py:method:: position_from_phase(phase, orbit=None)

      Update position of the observer based on the phase (in :math:`rad`) and the orbit.