Source code for madcubapy.coordinates.offsets
import astropy.units as u
import numpy as np
__all__ = [
'get_angular_offset_points',
'get_angular_separation',
'get_physical_offset_points',
'get_physical_separation',
]
[docs]
def get_angular_offset_points(points, ref_point, fitsmap):
"""
Get offset coordinates of a point or set of points, with respect to a
reference point in angular units.
Parameters
----------
points : `~numpy.ndarray`
Input point or points.
ref_point : `~numpy.ndarray`
Reference point.
fitsmap : `~madcubapy.io.MadcubaMap` or `~astropy.nddata.CCDData`
Map from which to get angular size of each pixel (CDELT1, CDELT2).
Returns
-------
angular_offset_points : `~astropy.units.Quantity`
Points with converted units to angular offset.
"""
cdelt_deg = fitsmap.wcs.wcs.cdelt[:2] * u.deg
angular_offset_points = (points - ref_point) * cdelt_deg
return angular_offset_points
[docs]
def get_angular_separation(points, ref_point, fitsmap):
"""
Get separation between a point or set of points, and a reference pixel in
angular units.
Parameters
----------
points : `~numpy.ndarray`
Input point or points.
ref_point : `~numpy.ndarray`
Reference point.
fitsmap : `~madcubapy.io.MadcubaMap` or `~astropy.nddata.CCDData`
Map from which to get angular size of each pixel (CDELT1, CDELT2).
Returns
-------
angular_separation : `~astropy.units.Quantity`
Separation between input points and reference point.
"""
angular_offset_points = get_angular_offset_points(points, ref_point, fitsmap)
angular_separation = np.linalg.norm(angular_offset_points, axis=-1)
return angular_separation
[docs]
def get_physical_offset_points(points, ref_point, fitsmap, distance):
"""
Get offset coordinates of a point or set of points, with respect to a
reference point in physical distance units.
Parameters
----------
points : `~numpy.ndarray`
Input point or points.
ref_point : `~numpy.ndarray`
Reference point.
fitsmap : `~madcubapy.io.MadcubaMap` or `~astropy.nddata.CCDData`
Map from which to get angular size of each pixel (CDELT1, CDELT2).
distance : `~astropy.units.quantity`
Distance from earth to object.
Returns
-------
physical_offset_points : `~astropy.units.Quantity`
Points with converted units to physical distance offset.
"""
angular_offset_points = get_angular_offset_points(points, ref_point, fitsmap)
physical_offset_points = (angular_offset_points * distance).to(
u.au, equivalencies=u.dimensionless_angles()
)
return physical_offset_points
[docs]
def get_physical_separation(points, ref_point, fitsmap, distance):
"""
Get separation between a point or set of points, and a reference pixel in
physical distance units.
Parameters
----------
points : `~numpy.ndarray`
Input point or points.
ref_point : `~numpy.ndarray`
Reference point.
fitsmap : `~madcubapy.io.MadcubaMap` or `~astropy.nddata.CCDData`
Map from which to get angular size of each pixel (CDELT1, CDELT2).
distance : `~astropy.units.quantity`
Distance from earth to object.
Returns
-------
physical_separation : `~astropy.units.Quantity`
Separation between input points and reference point.
"""
physical_offset_points = get_physical_offset_points(points, ref_point, fitsmap, distance)
physical_separation = np.linalg.norm(physical_offset_points, axis=-1)
return physical_separation
