spherical_project

sofia_redux.scan.coordinate_systems.projection.projection_numba_functions.spherical_project(x, y, cos_lat, sin_lat, celestial_pole_x, celestial_pole_y, celestial_cos_lat, celestial_sin_lat, native_pole_x)

Convert a single coordinate form a native pole to a celestial pole.

The following conversions are used depending on the value of the celestial pole native latitude (lat_cp) to convert the coordinates (x, y) to coordinates about the celestial pole (x_cp, y_cp). Here _cp denotes “celestial pole”, _np denotes “native pole”, and any numbers are in degrees.

lat_cp = 90:

x_cp = 180 + lon_np + x - lon_cp y_cp = y

lat_cp = -90:

x_cp = lon_np + lon_cp - x y_cp = -y

Otherwise:

d = x - lon_cp A = -cos(y)sin(d) B = sin(y)cos(lat_cp) - cos(y)sin(lat_cp)cos(d) x_cp = lon_np + arctan2(A, B) y_cp = arcsin(sin(y)sin(lat_cp) + cos(y)cos(lat_cp)cos(d))

The reverse operation (celestial to native poles) can be performed using spherical_deproject().

Parameters:

xfloat

The coordinate native longitude in radians.

yfloat

The coordinate native latitude in radians.

cos_latfloat

The cosine of y.

sin_latfloat

The sine of y.

celestial_pole_xfloat

The celestial pole native longitude in radians.

celestial_pole_yfloat

The celestial pole native latitude in radians.

celestial_cos_latfloat

The cosine of celestial_pole_y.

celestial_sin_latfloat

The sine of celestial_pole_y.

native_pole_xfloat

The coordinate’s native pole longitude in radians.

Returns:

theta, phifloat, float

The projection of (x, y) about the native pole on the celestial pole, with theta equivalent to y_cp and phi equivalent to x_cp where _cp denotes a projection about the celestial pole.