Sky2Pix_ConicEquidistant

class astropy.modeling.projections.Sky2Pix_ConicEquidistant(sigma=90.0, delta=0.0, **kwargs)

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

Conic equidistant projection - sky to pixel.

Corresponds to the COD projection in FITS WCS.

See Conic for a description of the entire equation.

The projection formulae are:

\[\begin{split}C &= \frac{180^\circ}{\pi} \frac{\sin\theta_a\sin\eta}{\eta} \\ R_\theta &= \theta_a - \theta + \eta\cot\eta\cot\theta_a \\ Y_0 = \eta\cot\eta\cot\theta_a\end{split}\]

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)

Evaluate the model on some input variables.

Attributes Documentation

param_names = ('sigma', 'delta')

Methods Documentation

classmethod evaluate(phi, theta, sigma, delta)

Evaluate the model on some input variables.