class astropy.modeling.projections.Sky2Pix_SlantOrthographic(xi=0.0, eta=0.0, **kwargs)[source]

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

Slant orthographic projection - sky to pixel.

Corresponds to the SIN projection in FITS WCS.

See Zenithal for a definition of the full transformation.

The following transformation applies when \(\xi\) and \(\eta\) are both zero.

\[R_\theta = \frac{180^{\circ}}{\pi}\cos \theta\]

But more specifically are:

\[\begin{split}x &= \frac{180^\circ}{\pi}[\cos \theta \sin \phi + \xi(1 - \sin \theta)] \\ y &= \frac{180^\circ}{\pi}[\cos \theta \cos \phi + \eta(1 - \sin \theta)]\end{split}\]

Attributes Summary


Methods Summary

evaluate(phi, theta, xi, eta) Evaluate the model on some input variables.

Attributes Documentation

eta = Parameter('eta', value=0.0)
param_names = ('xi', 'eta')
xi = Parameter('xi', value=0.0)

Methods Documentation

classmethod evaluate(phi, theta, xi, eta)[source]

Evaluate the model on some input variables.