SansonFlamsteedProjection

class sofia_redux.scan.coordinate_systems.projection.sanson_flamsteed_projection.SansonFlamsteedProjection

Bases: CylindricalProjection

Initialize a Sanson-Flamsteed projection.

The Sanson-Flamsteed projection is also known as the sinusoidal projection, and is a pseudo-cylindrical equal-area map projection. Poles are represented as points. Scale is constant along the central meridian, and the east-west scale is constant.

Methods Summary

get_fits_id()	Return the FITS ID for the projection.
get_full_name()	Return the full name of the projection.
get_offsets(theta, phi[, offsets])	Get the offsets given theta and phi.
get_phi_theta(offset[, phi_theta])	Return the phi (longitude) and theta (latitude) coordinates.

Methods Documentation

classmethod get_fits_id()

Return the FITS ID for the projection.

Returns:

str

classmethod get_full_name()

Return the full name of the projection.

Returns:

str

classmethod get_offsets(theta, phi, offsets=None)

Get the offsets given theta and phi.

Takes the theta (latitude) and phi (longitude) coordinates about the celestial pole and converts them to offsets from a reference position. For the Sanson-Flamsteed projection, this is given by:

x = phi * cos(theta) y = theta

Parameters:

thetaunits.Quantity

The theta angle.

phiunits.Quantity

The phi angle.

offsetsCoordinate2D, optional

An optional coordinate system in which to place the results.

Returns:

offsetsCoordinate2D

classmethod get_phi_theta(offset, phi_theta=None)

Return the phi (longitude) and theta (latitude) coordinates.

The phi and theta coordinates refer to the inverse projection (deprojection) of projected offsets about the native pole. phi is the deprojected longitude, and theta is the deprojected latitude of the offsets. For the Sanson-Flamsteed projection these are given as:

phi = x / cos(y) theta = y

Parameters:

offsetCoordinate2D

phi_thetaSphericalCoordinates, optional

An optional output coordinate system in which to place the results.

Returns:

coordinatesSphericalCoordinates