Pix2Sky_SlantOrthographic¶
-
class
astropy.modeling.projections.
Pix2Sky_SlantOrthographic
(xi=0.0, eta=0.0, **kwargs)[source]¶ Bases:
astropy.modeling.projections.Pix2SkyProjection
,astropy.modeling.projections.Zenithal
Slant orthographic projection - pixel to sky.
Corresponds to the
SIN
projection in FITS WCS.See
Zenithal
for a definition of the full transformation.The following transformation applies when \(\xi\) and \(\eta\) are both zero.
\[\theta = \cos^{-1}\left(\frac{\pi}{180^{\circ}}R_\theta\right)\]The parameters \(\xi\) and \(\eta\) are defined from the reference point \((\phi_c, \theta_c)\) as:
\[\begin{split}\xi &= \cot \theta_c \sin \phi_c \\ \eta &= - \cot \theta_c \cos \phi_c\end{split}\]- Parameters
- xifloat
Obliqueness parameter, ξ. Default is 0.0.
- etafloat
Obliqueness parameter, η. Default is 0.0.
Attributes Summary
Names of the parameters that describe models of this type.
Methods Summary
evaluate
(x, y, xi, eta)Evaluate the model on some input variables.
Attributes Documentation
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eta
= Parameter('eta', value=0.0)¶
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param_names
= ('xi', 'eta')¶ Names of the parameters that describe models of this type.
The parameters in this tuple are in the same order they should be passed in when initializing a model of a specific type. Some types of models, such as polynomial models, have a different number of parameters depending on some other property of the model, such as the degree.
When defining a custom model class the value of this attribute is automatically set by the
Parameter
attributes defined in the class body.
-
xi
= Parameter('xi', value=0.0)¶
Methods Documentation