Sky2Pix_ConicEqualArea#

class astropy.modeling.projections.Sky2Pix_ConicEqualArea(*args, **kwargs)[source]#

Bases: Sky2PixProjection, 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:

sigmafloat: \((\theta_1 + \theta_2) / 2\), where \(\theta_1\) and \(\theta_2\) are the latitudes of the standard parallels, in degrees. Default is 90.
deltafloat: \((\theta_1 - \theta_2) / 2\), where \(\theta_1\) and \(\theta_2\) are the latitudes of the standard parallels, in degrees. Default is 0.