Sky2Pix_ZenithalPerspective

class astropy.modeling.projections.Sky2Pix_ZenithalPerspective(mu=0.0, gamma=0.0, **kwargs)

Bases: astropy.modeling.projections.Sky2PixProjection, astropy.modeling.projections.Zenithal

Zenithal perspective projection - sky to pixel.

Corresponds to the AZP projection in FITS WCS.

\[\begin{split}x &= R \sin \phi \\ y &= -R \sec \gamma \cos \theta\end{split}\]

where:

\[R = \frac{180^{\circ}}{\pi} \frac{(\mu + 1) \cos \theta}{(\mu + \sin \theta) + \cos \theta \cos \phi \tan \gamma}\]

Parameters

mufloat

Distance from point of projection to center of sphere in spherical radii, μ. Default is 0.

gammafloat

Look angle γ in degrees. Default is 0°.

Attributes Summary

gamma
mu
param_names	Names of the parameters that describe models of this type.

Methods Summary

evaluate(phi, theta, mu, gamma)

Evaluate the model on some input variables.

Attributes Documentation

gamma = Parameter('gamma', value=0.0)

mu = Parameter('mu', value=0.0)

param_names = ('mu', 'gamma')

Names of the parameters that describe models of this type.

The parameters in this tuple are in the same order they should be passed in when initializing a model of a specific type. Some types of models, such as polynomial models, have a different number of parameters depending on some other property of the model, such as the degree.

When defining a custom model class the value of this attribute is automatically set by the Parameter attributes defined in the class body.

Methods Documentation

classmethod evaluate(phi, theta, mu, gamma)

Evaluate the model on some input variables.