Conic¶

class
astropy.modeling.projections.
Conic
(*args, meta=None, name=None, **kwargs)[source]¶ Bases:
astropy.modeling.projections.Projection
Base class for conic projections.
In conic projections, the sphere is thought to be projected onto the surface of a cone which is then opened out.
In a general sense, the pixeltosky transformation is defined as:
\[\begin{split}\phi &= \arg\left(\frac{Y_0  y}{R_\theta}, \frac{x}{R_\theta}\right) / C \\ R_\theta &= \mathrm{sign} \theta_a \sqrt{x^2 + (Y_0  y)^2}\end{split}\]and the inverse (skytopixel) is defined as:
\[\begin{split}x &= R_\theta \sin (C \phi) \\ y &= R_\theta \cos (C \phi) + Y_0\end{split}\]where \(C\) is the “constant of the cone”:
\[C = \frac{180^\circ \cos \theta}{\pi R_\theta}\]Attributes Summary
Attributes Documentation

delta
¶

param_names
= ('sigma', 'delta')¶

sigma
¶
