Offsets

The madcubapy.coordinates package offers a set of utility functions to work with coordinates and perform coordinates transformations.

Convert points to offsets

The get_angular_offset_points() and get_physical_offset_points() functions let the user get the coordinates of a point or set of points as angular or physical (providing a distance) offset with respect to a reference point.

>>> from madcubapy.io import MadcubaMap
>>> from madcubapy.coordinates import get_angular_offset_points

# Read map
>>> madcubamap = MadcubaMap.read("example_cube.fits")

# Convert points to angular offsets
>>> points = np.array([[120, 250], [140, 250], [160,250], [180,250]])
>>> ref_point = np.array([370, 300])
>>> new_points = get_angular_offset_points(points, ref_point, madcubamap)

>>> new_points
[[0.00430556 -0.00086111]
 [0.00396111 -0.00086111]
 [0.00361667 -0.00086111]
 [0.00327222 -0.00086111]] deg

# Convert points to physical offsets
>>> import astropy.units as u
>>> distance = 141 * u.pc
>>> new_points = get_physical_offset_points(points, ref_point, madcubamap, distance)

>>> new_points
[[2185.5  -437.1 ]
 [2010.66 -437.1 ]
 [1835.82 -437.1 ]
 [1660.98 -437.1 ]] AU

Calculate separations

The get_angular_separation() and get_physical_separation() functions let the user get the separation between a point or set of points and a reference point in angular or physical (providing a distance) units.

>>> from madcubapy.io import MadcubaMap
>>> from madcubapy.coordinates import get_angular_offset_points

# Read map
>>> madcubamap = MadcubaMap.read("example_cube.fits")

# Calculate angular separation between points
>>> points = np.array([[120, 250], [140, 250], [160,250], [180,250]])
>>> ref_point = np.array([370, 300])
>>> separation = get_angular_separation(points, ref_point, madcubamap)

>>> separation
[0.00439082 0.00405363 0.00371777 0.00338363] deg

# Calculate physical separation between points
>>> import astropy.units as u
>>> distance = 141 * u.pc
>>> separation = get_physical_separation(points, ref_point, madcubamap, distance)

>>> separation
[2228.78142939 2057.62242542 1887.13843753 1717.53048602] AU