This directory contains examples of how to use Astro::Coord::ECI and
its subclasses. The following examples are provided:

almanac
    This Perl script produces an almanac of Sun and Moon positions for
    the current day, or optionally for the next day. By default the
    almanac is for 1600 Pennsylvania Avenue Washington DC, but this can
    be changed by setting environment variable ALMANAC_POSITION, or
    specifying latitude north (degrees), longitude east (degrees),
    and height (meters) on the command. The option -help gets you
    brief help.

Astro-Coord-ECI.yml
    This CPAN client prefs file causes the satpass script to be
    installed by default. To use this file, place a copy of it in your
    CPAN client's preferences directory (e.g. .cpan/prefs for the 'cpan'
    client and a Unix-like operating system.)

azimuth
    This Perl script finds the next time the Sun passes a given azimuth
    (defaulting to 180 degrees) at Number 10 Downing Street.

closest
    This Perl script takes as input a time (suitable for Date::Manip), a
    right ascension and declination (both in degrees) and a list of the
    names of files containing TLE data. The output is the OID, right
    ascension, declination, and angular separation (in degrees) of the
    bodies closest to the given position as seen from Parliament House
    in Australia.

convert_tle
    This Perl script reads orbital data in either TLE or JSON format,
    and converts it to the other format. The JSON is similar to (read:
    uses the same keys as) the Space Track REST interface. The -help
    option gets you the documentation.

iss
    This Perl script uses Astro::SpaceTrack (not included) to download
    orbital data from http://spaceflight.nasa.gov/realdata/elements/ and
    predict visibility for the next week from the given location, which
    is hard-coded as 80 Wellington Street Ottawa Ontario Canada.

maidenhead
    This Perl script converts posiitons between latitude/longitude and
    Maidenhead locator grid positions.

passes
    This Perl script is kind of a "poor man's satpass", which downloads
    TLE data for the requested satellites (Astro::SpaceTrack and a Space
    Track account are required), and lists rise and set times in
    chronological order. You specify your location, Space Track account
    information, and other options either on the command line, in an
    initialization file, or both places. The --help option gets you the
    documentation.

positions
    This Perl script takes on its command line the names of files
    containing TLE data. All are read, and the elevation, azimuth and
    range of all satellites is displayed at one minute intervals for the
    current GMT day. Output is supressed when the satellite is below the
    horizon. The position is hard-wired to Parliament House, Australia.

sh_script
    This shell script executes the satpass Perl script (which comes with
    this distribution) passing it commands from a 'here document.' These
    commands download International Space Station data from
    http://spaceflight.nasa.gov/realdata/elements/ and predict
    visibility at the current time from 1600 Pennsylvania Avenue,
    Washington DC, USA.

solstice
    This Perl script calculates equinoxes and solstices for the given
    year, defaulting to the current year, in either UTC or local time.
    If DateTime::Calendar::Christian is available, dates will be given
    in the Julian or Gregorian calendars as appropriate.

tle_period.t
    This is not really a test, since I have no canonical data to test
    against. It is really a demonstration of the effect the model chosen
    and geophysical constants used have on the calculation of period. It
    expects to be run from the main distribution directory  as (e.g.)

    perl -Mblib eg/tle_period.t

    and it expects to find the orbital elements file sgp4-ver.tle in the
    t directory.

usno-seasons
    This script takes an optional Gregorian year on the command line
    (defaulting to the current year), and displays equinox and solstice
    times as calculated by Astro::Coord::ECI::Sun. For comparison, it
    downloads displays the times provided by the United States Naval
    Observatory, and the ecliptic longitude calculated by
    Astro::Coord::ECI::Sun for both its own and the Naval Observatory's
    times.

xml
    This demonstration script downloads International Space Station TLE
    data from Celestrak, predicts passes over The Hague, Netherlands,
    and displays the results as XML, using XML::Writer. The pass_variant
    attribute is used to control what events of a pass are displayed.

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