Access coordinate components

Individual coordinates can be accessed via attributes on the SkyCoord object, but the names of the components of the coordinates can depend on the the frame and the chosen representation (e.g., Cartesian versus spherical).

Helioprojective

For the helioprojective frame, the theta_x and theta_y components are accessed Tx and Ty, respectively:

>>> from astropy.coordinates import SkyCoord
>>> import astropy.units as u

>>> from sunpy.coordinates import frames

>>> c = SkyCoord(-500*u.arcsec, 100*u.arcsec, frame=frames.Helioprojective)
>>> c.Tx
<Longitude -500. arcsec>
>>> c.Ty
<Latitude 100. arcsec>

Heliocentric

Heliocentric is typically used with Cartesian components:

>>> c = SkyCoord(-72241.0*u.km, 361206.1*u.km, 589951.4*u.km, frame=frames.Heliocentric)
>>> c.x
<Quantity -72241. km>
>>> c.y
<Quantity 361206.1 km>
>>> c.z
<Quantity 589951.4 km>

HeliographicStonyhurst and HeliographicCarrington

Both of the heliographic frames have the components of latitude, longitude and radius:

>>> c = SkyCoord(70*u.deg, -30*u.deg, 1*u.AU, frame=frames.HeliographicStonyhurst)
>>> c.lat
<Latitude -30. deg>
>>> c.lon
<Longitude 70. deg>
>>> c.radius
<Distance 1. AU>

Heliographic Stonyhurst, when used with Cartesian components, is known as Heliocentric Earth Equatorial (HEEQ). Here’s an example of how to use HeliographicStonyhurst for HEEQ coordinates:

>>> c = SkyCoord(-72241.0*u.km, 361206.1*u.km, 589951.4*u.km,
...              representation_type='cartesian', frame=frames.HeliographicStonyhurst)
>>> c.x
<Quantity -72241. km>
>>> c.y
<Quantity 361206.1 km>
>>> c.z
<Quantity 589951.4 km>