Overlaying coordinate systemsΒΆ

For the example in the following page we start from the example introduced in Getting started.

The coordinates shown by default in a plot will be those derived from the WCS or transformation passed to the wcsaxes.WCSAxes class. However, it is possible to overlay different coordinate systems using the wcsaxes.WCSAxes.get_coords_overlay() method:

overlay = ax.get_coords_overlay('fk5')
_images/overlaying_coordinate_systems-2.png

The object returned is a CoordinatesMap, the same type of object as ax.coord. It can therefore be used in the same way as ax.coord to set the ticks, tick labels, and axis labels properties:

ax.coords['glon'].set_ticks(color='white')
ax.coords['glat'].set_ticks(color='white')

ax.coords['glon'].set_axislabel('Galactic Longitude')
ax.coords['glat'].set_axislabel('Galactic Latitude')

ax.coords.grid(color='yellow', linestyle='solid', alpha=0.5)

overlay['ra'].set_ticks(color='white')
overlay['dec'].set_ticks(color='white')

overlay['ra'].set_axislabel('Right Ascension')
overlay['dec'].set_axislabel('Declination')

overlay.grid(color='white', linestyle='solid', alpha=0.5)
_images/overlaying_coordinate_systems-3.png