Sky2Pix_SlantOrthographic

class astropy.modeling.projections.Sky2Pix_SlantOrthographic(*args, **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

eta

param_names

Names of the parameters that describe models of this type.

xi

Attributes Documentation

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

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.

xi = _ParameterDS('xi', value=0.0)