Sky2Pix_ConicEqualArea

class astropy.modeling.projections.Sky2Pix_ConicEqualArea(sigma=90.0, delta=0.0, **kwargs)[source] [edit on github]

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

Alber’s conic equal area projection - sky to pixel.

Corresponds to the COE projection in FITS WCS.

See Conic for a description of the entire equation.

The projection formulæ are:

\[\begin{split}C &= \gamma / 2 \\ R_\theta &= \frac{180^\circ}{\pi} \frac{2}{\gamma} \sqrt{1 + \sin \theta_1 \sin \theta_2 - \gamma \sin \theta} \\ Y_0 &= \frac{180^\circ}{\pi} \frac{2}{\gamma} \sqrt{1 + \sin \theta_1 \sin \theta_2 - \gamma \sin((\theta_1 + \theta_2)/2)}\end{split}\]

where:

\[\gamma = \sin \theta_1 + \sin \theta_2\]
Parameters:

sigma : float

\((\theta_1 + \theta_2) / 2\), where \(\theta_1\) and \(\theta_2\) are the latitudes of the standard parallels, in degrees. Default is 90.

delta : float

\((\theta_1 - \theta_2) / 2\), where \(\theta_1\) and \(\theta_2\) are the latitudes of the standard parallels, in degrees. Default is 0.

Attributes Summary

param_names

Methods Summary

evaluate(phi, theta, sigma, delta)

Attributes Documentation

param_names = (‘sigma’, ‘delta’)

Methods Documentation

classmethod evaluate(phi, theta, sigma, delta)[source] [edit on github]