Binary star position angle and separation calculator

Originally created to help verify the pixel scale of a new CCD at Paranal. Orbital elements can be found in the USNO's 6th Catalogue of Orbits of Visual Binary Stars. Type in the "Star name" box to look up USNO designations, or use the sky map search box to find objects by any designation. Or, type your own orbital elements in the boxes. The method for calculating the observable parameters is based on algorithms presented in Jean Meeus' Astronomical algorithms.

Orbital elements

Star name
Period [years]
Periastron date [years]
Semimajor axis [arcsec]
Inclination [°]
Argument of periastron [°]
Position angle of ascending node [°]
Epoch of observation [years]


Seeing: arcsec