Sky2Pix_SlantOrthographic#

class astropy.modeling.projections.Sky2Pix_SlantOrthographic(*args, **kwargs)[source]#

Bases: Sky2PixProjection, 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:

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

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)#