Last modified: June 2019

AHELP for CIAO 4.16


Context: contrib


Utility routines for working with Astronomical positions.


from coords.utils import point_separation
sep = point_separation(long1, lat1, long2, lat2)

sep, long<n>, and lat<n> are in degrees.

The Python help command - e.g. help(point_separation) - can be used.


The coords.utils module contains routines for working with Astronomical positions, based on the Starlink SLALIB module, and the Python conversion, pyslalib, by Scott Ransom. At present only one routine is exported by the module, but a number of routines are also available - use help(coords.utils) to see what is available. These routines are not exported since their interface is not guaranteed to be stable.

Loading the routines

The module can be loaded into a Python session or script by saying:

import coords_utils


from coords.utils import point_separation


>>> from coords.utils import point_separation
>>> sep = point_separation(8.80125, -43.35556, 8.815, -43.566)
>>> print("Separation = {:.2f} arcmin".format(sep * 60))
Separation = 12.64 arcmin

The return value from point_separation is in degrees, so we convert it to arcminutes before printing it out.

Changes in the scripts 4.5.4 (August 2013) release

Documentation for the coords.utils module is new in this release.

About Contributed Software

This module is not an official part of the CIAO release but is made available as "contributed" software via the CIAO scripts page. Please see this page for installation instructions.

See Also

coords_chandra, coords_format, coords_gratings, identify_name