class astropy.coordinates.CompositeTransform(transforms, fromsys, tosys, priority=1, register_graph=None, collapse_static_mats=True)[source]

Bases: CoordinateTransform

A transformation constructed by combining together a series of single-step transformations.

Note that the intermediate frame objects are constructed using any frame attributes in toframe or fromframe that overlap with the intermediate frame (toframe favored over fromframe if there’s a conflict). Any frame attributes that are not present use the defaults.

transformspython:sequence of CoordinateTransform object

The sequence of transformations to apply.


The coordinate frame class to start from.


The coordinate frame class to transform into.

prioritypython:float or python:int

The priority if this transform when finding the shortest coordinate transform path - large numbers are lower priorities.

register_graphTransformGraph or python:None

A graph to register this transformation with on creation, or None to leave it unregistered.


If True, consecutive StaticMatrixTransform will be collapsed into a single transformation to speed up the calculation.

Methods Summary

__call__(fromcoord, toframe)

Does the actual coordinate transformation from the fromsys class to the tosys class.

Methods Documentation

__call__(fromcoord, toframe)[source]

Does the actual coordinate transformation from the fromsys class to the tosys class.

fromcoordBaseCoordinateFrame subclass instance

An object of class matching fromsys that is to be transformed.


An object that has the attributes necessary to fully specify the frame. That is, it must have attributes with names that match the keys of the dictionary tosys.frame_attributes. Typically this is of class tosys, but it might be some other class as long as it has the appropriate attributes.

tocoordBaseCoordinateFrame subclass instance

The new coordinate after the transform has been applied.