# Sky2Pix_ConicEqualArea¶

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

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

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]