Pix2Sky_ZenithalPerspective

class astropy.modeling.projections.Pix2Sky_ZenithalPerspective(mu=0.0, gamma=0.0, **kwargs)[source] [edit on github]

Bases: astropy.modeling.projections.Pix2SkyProjection, astropy.modeling.projections.Zenithal

Zenithal perspective projection - pixel to sky.

Corresponds to the AZP projection in FITS WCS.

\[\begin{split}\phi &= \arg(-y \cos \gamma, x) \\ \theta &= \left\{\genfrac{}{}{0pt}{}{\psi - \omega}{\psi + \omega + 180^{\circ}}\right.\end{split}\]

where:

\[\begin{split}\psi &= \arg(\rho, 1) \\ \omega &= \sin^{-1}\left(\frac{\rho \mu}{\sqrt{\rho^2 + 1}}\right) \\ \rho &= \frac{R}{\frac{180^{\circ}}{\pi}(\mu + 1) + y \sin \gamma} \\ R &= \sqrt{x^2 + y^2 \cos^2 \gamma}\end{split}\]
Parameters:

mu : float

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

gamma : float

Look angle γ in degrees. Default is 0°.

Attributes Summary

gamma
mu
param_names

Methods Summary

check_mu(value)

Deprecated since version 1.1.

evaluate(x, y, mu, gamma)

Attributes Documentation

gamma
mu
param_names = ('mu', 'gamma')

Methods Documentation

check_mu(value)[source] [edit on github]

Deprecated since version 1.1: this method was never intended as part of the public API and will be removed; if you do need its functionality use model.mu.validator(val)

classmethod evaluate(x, y, mu, gamma)[source] [edit on github]