Pix2Sky_ConicEqualArea

class astropy.modeling.projections.Pix2Sky_ConicEqualArea(*args, **kwargs)[source]

Bases: astropy.modeling.projections.Pix2SkyProjection, astropy.modeling.projections.Conic

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

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.