js_astro

Sample code for astrological calculation written by JavaScript.

This library intent to:

• calculation of major planetary position(geocentric, apparent longitude) for 0-4000 A.D. within 1 arcminute.
• calculation of house cusp longitudes

Requirement

Environment

Newest Browser, but all comments are written in Japanese(Shift-JIS).

Library

Some functions requires spirntf.js, but if you don't want to use function cnv2*, not required.

License

Files in this repository are released under MIT license.

Usage

Calculate for planetary position

Include all libraries, and call calPlanetPositon2 as:

var planetPosition = new Array();
planetPosition = calPlanetPosition2( year, month, day, hour, minute, longitude, latitude );

calPlanetPosition2 returns array of 20 values:

• Julian day
• Planetary Position(Geocentric apparent ecliptic longitude): Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto
• Lunar Node & apogee Longitude(from approximate osculate orbital elements)
• Longitude of Ascendant, MC(Mid heaven)
  • All value is expressed in degree, without Julian day.
• Position of minor planets(Geocentric apparent ecliptic longitude): Ceres, Pallas, Juno, Vesta, Chiron

Calculate for house cusp longitudes

Include all libraries, and call calHouseCusp2 as:

var cuspLongitudes = new Array();
cuspLongitudes = calHouseCusp2( year, month, day, hour, minute, longitude, latitude, 1 );

Last Argument 1 means Placidus house system.

calHouseCusp2 returns array of house cusp longitude(Index of this array starts 1, not 0).

Important notice

In this library, definition of major planets and minor planets is modern astrological, not currently astronomical. I assume Pluto as major planet and Ceres as minor planet, which they are dwarf planets in currently astronomy.

Positions of minor planets can calculate between December 30, 1924 12:00 TT and December 31, 2124 12:00 TT only.

Timezone used in this library is Japan Standard Time(UTC+0900). You may consider to wrapper function to convert your local timezone. I never consider any Daylight Saving Time in past and future.

This library assumes eastern geographical longitude and northern geographical latitude as plus(eg. Tokyo: 139E42 = +139.70, 35N41 = +35.68).

Demonstration

To test this library, try this.

Errata for Leaflet written in Japanese

This library has a leaflet, and this leaflet has some error. Errata is here.