Predicting Local Circumstances of Solar Eclipses

Predict local circumstances (UTC and topocentric coordinates) of solar eclipses.

This submission is a MATLAB script named solar_eclipse that can be used to predict local circumstances of solar eclipses. This computer program provides the universal times and topocentric coordinates of the Sun and Moon at the beginning and end of the penumbra contacts, and the time and coordinates at maximum eclipse. The source 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 solar_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 script uses a combination of one-dimensional minimization and root-finding to solve this classical astronomy problem. The objective function used in these calculations is the difference between the selenocentric (Moon-centered) separation angle between the axis of the lunar shadow and an Earth observer, and the penumbra shadow angle.