/ 
DateTime-Util-Astro-0.09
River stage one • 1 direct dependent • 1 total dependent
/ DateTime::Util::Astro::Common

NAME

DateTime::Util::Astro::Common - Common Utilities For Astronomical Calendar Calculations

SYNOPSIS

use DateTime::Util::Astro::Common qw(
  aberration
  dt_from_dynamical
  dynamical_moment_from_dt
  ephemeris_correction
  equation_of_time
  julian_centuries
  local_from_apparent 
  nutation
  obliquity
  standard_from_local
  standard_from_universal
  universal_from_local
  universal_from_standard
  SPRING
  SUMMER
  AUTUMN
  WINTER
  MEAN_TROPICAL_YEAR
  RD_MOMENT_1900_JAN_1
  RD_MOMENT_1810_JAN_1
  RD_MOMENT_J2000
);

my $location = DateTime::Util::Astro::Location->new(
  longitude => $longitude,
  latitude  => $latitude,
  zone      => $zone,
  elevation => $elevation
);

DESCRIPTION

DateTime::Util::Astro::Location implements some functions that are commonly used for astronomical calculations. As with other DateTime::Util::Astro:: modules this module only implements the bare minimum required to make astronomical calendars.

FUNCTIONS

aberration($dt)

Calculates the effect of the sun's moving during the time its light takes takes to reach the Earth

dt_from_dynamical($moment)

dynamical_moment_from_dt($dt)

julian_centuries($moment)

The number and fraction of uniform-length centuries at a given moment.

ephemeris_correction($dt)

Calculates the offset from "dynamical time", which is caused by the retarding effects of tide and other atmospheric conditions.

EC_C

EC_X

EC1

EC2

EC3

EC4

EC5

EC6

These are used to calculate the ephemeris_correction.

equation_of_time($dt)

Calculates the difference between "apparent midnight" and the "mean midnight"

julian_centuris($dt)

Calculates the fractional number of centuries since January 1, 2000 (Gregorian).

local_from_apparent($dt)

nutation($dt)

Calculates the effect caused by the wobble of the Earth.

obliquity($)

Calculates the inclination of th Earth

local_from_standard($dt, $location)

local_from_universal($dt, $location)

standard_from_local($dt,$location)

standard_from_universal($dt,$location)

universal_from_local($dt,$location)

universal_from_standard($dt,$location)

CONSTANTS

SPRING

SUMMER

AUTUMN

WINTER

The solar longitude for equinoxes and solstices.

MEAN_TROPICAL_YEAR

The time it takes for the mean sun to return to the same position relative to the celestial equator

RD_MOMENT_1900_JAN_1

RD_MOMENT_1810_JAN_1

RD_MOMENT_J2000

TODO

DateTime::Util::Astro::Location probably isn't worth existing, as I believe the math involved with locations can probably be done via DateTime itself, or at least via DateTime::Locale and DateTime::TimeZone objects.

Hence it is foraseeable that DateTime::Util::Astro::Location will be phased out eventually and I've opted to keep it as a private class within his module, so that it doesn't pollute users' file systems.

AUTHOR

Daisuke Maki <daisuke@cpan.org>

REFERENCES

[1] Edward M. Reingold, Nachum Dershowitz
    "Calendrical Calculations (Millenium Edition)", 2nd ed.
     Cambridge University Press, Cambridge, UK 2002

SEE ALSO

DateTime DateTime::Event::Lunar DateTime::Event::SolarTerm DateTime::Util::Astro::Moon DateTime::Util::Astro::Sun