Guides

Houses & Zodiacs

House systems

Twelve systems are built in: placidus, whole_sign, equal, porphyry, koch, regiomontanus, campanus, alcabitius, morinus, meridian, polich_page, and vehlow. Pass the name as the last argument, or as houseSystem in the options object.

cusp	placidus	koch	whole_sign	equal
1 (ASC)	10°54' Leo	10°54' Leo	29°59' Cancer	10°54' Leo
2	5°19' Virgo	8°57' Virgo	29°59' Leo	10°54' Virgo
3	3°46' Libra	7°37' Libra	0°00' Libra	10°54' Libra
4	6°02' Scorpio	6°02' Scorpio	0°00' Scorpio	10°54' Scorpio
5	9°29' Sagittarius	12°52' Sagittarius	29°59' Scorpio	10°54' Sagittarius
6	11°23' Capricorn	13°02' Capricorn	0°00' Capricorn	10°54' Capricorn
7	10°54' Aquarius	10°54' Aquarius	29°59' Capricorn	10°54' Aquarius
8	5°19' Pisces	8°57' Pisces	0°00' Pisces	10°54' Pisces
9	3°46' Aries	7°37' Aries	0°00' Aries	10°54' Aries
10 (MC)	6°02' Taurus	6°02' Taurus	29°59' Aries	10°54' Taurus
11	9°29' Gemini	12°52' Gemini	0°00' Gemini	10°54' Gemini
12	11°23' Cancer	13°02' Cancer	0°00' Cancer	10°54' Cancer

The same instant, four house systems. The Ascendant and Midheaven are identical across all of them (they are astronomical, not a division rule); the intermediate cusps are where the systems disagree.

Tropical and sidereal

The default zodiac is tropical. Sidereal modes subtract an ayanamsa:

zodiac.ts

engine.chart(1990, 6, 10, 14, 30, 0, 27.95, -82.46, {
zodiac: "sidereal:lahiri",
});

Embedded ayanamsas: lahiri, fagan_bradley, krishnamurti, raman, and yukteshwar. Two star-anchored modes (galcent_0sag, true_citra) need the fixed-star catalog from the Node data tier; see Data Tiers.

	tropical	lahiri	fagan/bradley	krishnamurti
☉ sun	19°27' Gemini	25°43' Taurus	24°50' Taurus	25°49' Taurus
☽ moon	13°17' Capricorn	19°33' Sagittarius	18°40' Sagittarius	19°39' Sagittarius
☿ mercury	27°50' Taurus	4°07' Taurus	3°14' Taurus	4°13' Taurus
♀ venus	13°01' Taurus	19°18' Aries	18°25' Aries	19°24' Aries
♂ mars	7°30' Aries	13°46' Pisces	12°53' Pisces	13°52' Pisces

The same positions, tropical and three sidereal ayanamsas. Each sidereal mode subtracts its ayanamsa, shifting every longitude back by ~24°.

Angles

Every chart includes the ascendant and midheaven (chart.angles.asc, chart.angles.mc); the vertex and east point are also computed. House cusps are derived by closed-form angles, not iteration.

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