# Pix2Sky_CylindricalPerspective¶

class astropy.modeling.projections.Pix2Sky_CylindricalPerspective(*args, **kwargs)[source]

Cylindrical perspective - pixel to sky.

Corresponds to the CYP projection in FITS WCS.

$\begin{split}\phi &= \frac{x}{\lambda} \\ \theta &= \arg(1, \eta) + \sin{-1}\left(\frac{\eta \mu}{\sqrt{\eta^2 + 1}}\right)\end{split}$

where:

$\eta = \frac{\pi}{180^{\circ}}\frac{y}{\mu + \lambda}$
Parameters
mufloat

Distance from center of sphere in the direction opposite the projected surface, in spherical radii, μ. Default is 1.

lamfloat

Radius of the cylinder in spherical radii, λ. Default is 1.

Attributes Summary

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

Attributes Documentation

lam = _ParameterDS('lam', value=1.0)[source]
mu = _ParameterDS('mu', value=1.0)[source]
param_names = ('mu', 'lam')

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.