Predicting Local Circumstances of Lunar Eclipses

Predict the local circumstances (times and topocentric coordinates of the Moon) of lunar eclipses.

This submission is a MATLAB script named lunar_eclipse that can be used to predict local circumstances of lunar eclipses. This software provides the eclipse type, the universal times and topocentric coordinates of the Moon at the beginning and end of the penumbra contacts, and the time and coordinates at maximum eclipse. The ephemeris for this routine is a JPL binary ephemeris file.

This application uses several functions ported to MATLAB from the Fortran version of the NOVAS (Naval Observatory Vector Astrometry Subroutines) source code developed at the United States Naval Observatory. Information about the NOVAS software suite can be found at https://aa.usno.navy.mil/software/novas_info.

The lunar_eclipse MATLAB script also uses routines from the MICE software suite to read and evaluate the DE430 ephemeris data. Ephemeris files, platform dependent versions of the MICE mex file and other useful MATLAB functions are available at naif.jpl.nasa.gov/naif/toolkit_MATLAB.html. MICE is a MATLAB implementation of the SPICE library created by JPL.

This MATLAB script uses a combination of one-dimensional minimization and root-finding to solve this classic problem. The objective function used in these calculations involves the geocentric separation angle between the center of the Moon and the anti-Sun position vector or shadow axis, and the semidiameter and horizontal parallax of the Sun and Moon.