# Coordinates (`heliopy.coordinates`)¶

## heliopy.coordinates Package¶

### Creating coordinate objects¶

Coordinate objects can be created using the coordinate frame classes in `heliopy.coordinates.frames`, for example, to create a coordinate in a GSE frame:

```>>> from astropy.constants import au
>>> import heliopy.coordinates.frames as frames
>>> hee_coord = frames.HeliocentricEarthEcliptic(1 * au, 0 * au, 0 * au)
>>> hee_coord
<HeliocentricEarthEcliptic Coordinate (obstime=None): (x, y, z) in m
(1.49597871e+11, 0., 0.)>
```

### Transforming between coordinate systems¶

To transform between coordinate frames, the `transform_to()` method can be called on a coordinate object:

```>>> from datetime import datetime
>>> from astropy.constants import au
>>> import heliopy.coordinates.frames as frames
>>>
>>> hee_coord = frames.HeliocentricEarthEcliptic(1 * au, 0 * au, 0 * au,
...     obstime=datetime(1992, 12, 21))
>>> gse_coord = hee_coord.transform_to(frames.GeocentricSolarEcliptic)
>>> gse_coord
<GeocentricSolarEcliptic Coordinate (obstime=None): (x, y, z) in m
(-2.42947355e+09, 0., 0.)>
```

## heliopy.coordinates.frames Module¶

This submodule contains various space physics coordinate frames for use with the `astropy.coordinates` module.

Warning

The functions in this submodule should never be called directly, transforming between coordinate frames should be done using `transform_to()` on coordinate frame objects. See above for an example.

### Transformation graph¶

The diagram below shows all of the coordinate systems built into the ~astropy.coordinates package, their aliases (useful for converting other coordinates to them using attribute-style access) and the pre-defined transformations between them. The user is free to override any of these transformations by defining new transformations between these systems, but the pre-defined transformations should be sufficient for typical usage.

The color of an edge in the graph (i.e. the transformations between two frames) is set by the type of transformation; the legend box defines the mapping from transform class name to color.

• AffineTransform:

• FunctionTransform:

• FunctionTransformWithFiniteDifference:

• StaticMatrixTransform:

• DynamicMatrixTransform:

### Functions¶

 `hee_to_gse`(hee_coord, gse_frame) Convert from HEE to GSE coordinates.

### Classes¶

 `GeocentricSolarEcliptic`(*args[, copy, …]) A coordinate frame in the Geocentric Solar Ecliptic (GSE) system. `HeliocentricEarthEcliptic`(*args[, copy, …]) A coordinate frame in the Heliocentric Earth Ecliptic (HEE) system.