Sky2Pix_ConicEqualArea

class astropy.modeling.projections.Sky2Pix_ConicEqualArea(*args, meta=None, name=None, **kwargs)[source]

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 formulae 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.

Methods Summary

evaluate(phi, theta, sigma, delta) Evaluate the model on some input variables.

Methods Documentation

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

Evaluate the model on some input variables.