.. currentmodule:: ctapipe.coordinates
ctapipe.coordinates contains coordinate frame definitions and
coordinate transformation routines that are associated with the
reconstruction of Cherenkov telescope events.
It is built on astropy.coordinates
,
which internally use the ERFA coordinate transformation library,
the open-source-licensed fork of the IAU SOFA system.
The coordinate library defines a set of frames,
which represent different coordinate reprentations.
Coordinates should be described using an astropy.coordinates.SkyCoord
in the appropriate frame.
The following special frames are defined for CTA:
- CameraFrame
- EngineeringCameraFrame
- TelescopeFrame
- NominalFrame
- GroundFrame
- TiltedGroundFrame
they can be transformed to and from any other astropy.coordinates frame, like astropy.coordinates.AltAz or astropy.coordinates.ICRS (RA/Dec)
The two different coordinate frames are shown here:
.. plot:: ../examples/plot_camera_frames.py :include-source:
The CameraFrame is used internally in ctapipe
and comes from sim_telarray
.
It abstracts the transformation differences between 1 and 2 mirror telescopes away.
The EngineeringCameraFrame is used by MAGIC, FACT and the H.E.S.S. analysis
software.
.. automodapi:: ctapipe.coordinates :no-inheritance-diagram:
.. automodapi:: ctapipe.coordinates.camera_frame :no-inheritance-diagram:
.. automodapi:: ctapipe.coordinates.telescope_frame :no-inheritance-diagram:
.. automodapi:: ctapipe.coordinates.nominal_frame :no-inheritance-diagram:
.. automodapi:: ctapipe.coordinates.ground_frames :no-inheritance-diagram: