class wcsaxes.SphericalCircle(center, radius, resolution=100, vertex_unit=Unit("deg"), **kwargs)[source]

Bases: matplotlib.patches.Polygon

Create a patch representing a spherical circle - that is, a circle that is formed of all the points that are within a certain angle of the central coordinates on a sphere. Here we assume that latitude goes from -90 to +90

This class is needed in cases where the user wants to add a circular patch to a celestial image, since otherwise the circle will be distorted, because a fixed interval in longitude corresponds to a different angle on the sky depending on the latitude.


center : tuple or Quantity

This can be either a tuple of two Quantity objects, or a single Quantity array with two elements.

radius : Quantity

The radius of the circle

resolution : int, optional

The number of points that make up the circle - increase this to get a smoother circle.

vertex_unit : Unit

The units in which the resulting polygon should be defined - this should match the unit that the transformation (e.g. the WCS transformation) expects as input.


Additional keyword arguments are passed to Polygon