==========
CENA's FOV
==========

CENA has 7 channels of fields of view (FoV).
The FoV is fixed in terms of the spacecraft.

CENA FoV in CENA frame
======================

To be written

.. todo::

        Write the section

CENA FoV in Spacecraft frame
============================


To be writtern.

.. todo::

        Write the section


CENA FoV crossing to the lunar surface
======================================

CENA FoV crossing at the surface of the Moon in ME frame can be conducted
using :mod:`irfpy.cena.intersection` module.

Use func:`irfpy.cena.intersection.get_center_me` which provides the
intersection between the center of the given channel and the lunar surface
at a given time.

First specify the time.

>>> import datetime
>>> t = datetime.datetime(2009, 1, 31, 3, 25, 17)

Then call the function func:`irfpy.cena.intersection.get_center_me` to get the crosssection of
the center position of the channel.

>>> from irfpy.cena.intersection import get_center_me
>>> lon, lat = get_center_me(t, 3)

Here ``3'' is the channel number 3, i.e. the boresight direction.

>>> print(lon)
72.5
>>> print(lat)
62.5