Sidereal Astrology Houses API

Cosmic Ephemeris uses Western (tropical), geocentric astrology by default. Sidereal calculations are applied only when explicitly enabled using "zodiac": "sidereal" and an ayanamsa selection. This endpoint provides sidereal coordinate transforms only and does not implement full Vedic astrology systems.

The Sidereal Houses API calculates astrological house systems and chart angles using sidereal zodiac coordinates derived from the selected ayanamsa. In addition to house cusps, this endpoint returns full chart context required for accurate rendering and analysis. All access uses API key authentication.

Endpoint

POST https://api.cosmicephemeris.com/api/astro/houses

Include Authorization: Bearer <API_KEY>.

Supported House Systems

  • equal (default)
  • whole_sign
  • placidus (opt-in beta)
  • porphyry (opt-in beta)
  • meridian (opt-in beta)
  • campanus (opt-in beta)
  • regiomontanus (opt-in beta)
  • alcabitius (opt-in beta)
  • koch (opt-in beta)
  • morinus (opt-in beta)
  • topocentric (opt-in beta; Polich/Page house geometry only)
  • sripati (opt-in beta; forward midpoints of Porphyry sectors)
  • vehlow (opt-in beta; equal 30-degree houses with the Ascendant centered in house 1)
  • horizon (opt-in beta; equal local-horizon azimuth divisions projected through vertical circles)
  • krusinski (opt-in beta; equal Ascendant-zenith great-circle divisions projected through celestial meridian circles)
  • sunshine (opt-in beta; Treindl construction from trisected solar diurnal and nocturnal semi-arcs)
  • sunshine_alt (opt-in beta; Makransky projection of trisected solar semi-arc points)
  • savard (opt-in beta; Savard-A latitude-circle geometry projected through the prime vertical)
  • pullen_sd (opt-in beta; Pullen Sinusoidal Delta ecliptic-quadrant weighting)
  • pullen_sr (opt-in beta; Pullen Sinusoidal Ratio ecliptic-quadrant weighting)
  • carter (opt-in beta; Carter Poli-Equatorial equal right-ascension divisions from the Ascendant)
  • apc (opt-in beta; Ascendant Parallel Circle divided above and below the horizon)
  • equal_mc (opt-in beta; twelve equal ecliptic houses with MC at cusp 10)
  • natural (opt-in beta; sign-boundary houses beginning at zero degrees Aries in the selected zodiac)
  • gauquelin (opt-in beta on Houses only; 36 clockwise semiarc sector boundaries)

The response contains only the selected system. whole is accepted as a legacy alias for whole_sign.

Beta Placidus computes tropical semiarc cusps. Beta Porphyry divides each tropical ecliptic quadrant between the four chart angles into thirds. Beta Meridian divides right ascension equally from RAMC and projects each division onto the ecliptic; cusp 10 is MC and cusp 1 is the Equatorial Ascendant. Beta Campanus divides the prime vertical equally and projects great circles through its divisions and the north/south horizon points onto the ecliptic. Beta Regiomontanus instead divides the celestial equator equally and projects its divisions through the same horizon points. Beta Alcabitius trisects the Ascendant's upper and lower right-ascension arcs and projects the divisions onto the ecliptic along hour circles. Beta Koch trisects the natal Midheaven degree's birthplace rising-to-culmination semiarc and uses intermediate physical Ascendants. Beta Morinus transforms twelve equally spaced celestial-equator points anchored at RAMC directly into ecliptic longitude; its cusps 1 and 10 are not the physical Ascendant and MC. Beta Topocentric derives intermediate poles by trisecting the tangent of latitude, uses the physical Ascendant and MC for cusps 1 and 10, and changes house cusps only. Beta Sripati moves each cusp to the forward midpoint of its preceding Porphyry sector; cusps 1 and 10 are not the physical angles. Beta Vehlow places equal 30-degree cusps from Ascendant minus 15 degrees, so the Ascendant is centered in house 1 and MC remains separate. Beta Horizon/Azimuth projects twelve equal local-horizon divisions through vertical circles to the ecliptic; cusp 1 is the prime-vertical intersection rather than the physical Ascendant, and cusp 10 is MC. Beta Krusinski-Pisa-Goelzer projects twelve equal Ascendant-zenith great-circle divisions through celestial meridian circles; cusps 1 and 10 are the physical Ascendant and Midheaven. Beta Sunshine uses the Treindl construction from trisected solar diurnal and nocturnal semi-arcs; cusps 1 and 10 are the physical Ascendant and Midheaven. Beta Sunshine alternative independently uses Makransky prime-vertical geometry for the same solar house points. Beta Savard-A projects one-third and two-thirds geographic-latitude circles through the prime vertical; cusps 1 and 10 are the physical Ascendant and Midheaven and opposite cusps are antipodal. Beta Pullen SD redistributes each ecliptic quadrant's deviation from 90 degrees with quarter/half/quarter weighting; cusp 10 is the physical Midheaven and cusp 1 uses the orientation-adjusted Ascendant. Pullen SR proportions complementary quadrant house widths as rx, x, rx and r³x, r⁴x, r³x; cusp 10 is the physical Midheaven and cusp 1 uses the orientation-adjusted Ascendant. Carter divides right ascension into twelve equal arcs from the orientation-adjusted Ascendant and projects them to the ecliptic; cusp 10 is generally not the physical Midheaven. APC divides the Ascendant parallel into six sectors below and six above the horizon; cusps 1 and 10 are the orientation-adjusted angles and intermediate opposite cusps are not generally antipodal. Equal MC fixes the physical Midheaven at cusp 10 and places twelve equal 30-degree ecliptic houses; cusp 1 is generally not the physical Ascendant. Natural fixes cusp 1 at zero degrees Aries in the selected zodiac; sidereal cusps remain sidereal sign boundaries while ayanamsa applies to the returned physical angles. Gauquelin returns 36 clockwise semiarc sector boundaries in the houses map and subtracts the selected ayanamsa once; it is not a Natal SVG system. Campanus, Regiomontanus, Alcabitius, and Koch use MC as cusp 10 and the physical Ascendant as cusp 1. The twenty-one angle-derived twelve-house beta systems and Houses-only Gauquelin subtract the selected date-aware ayanamsa from every cusp. Natural instead keeps its cusps on the selected zodiac sign boundaries. Every beta rejects undefined response geometry with HTTP 400; there is no silent substitution of another house system. Regiomontanus, Alcabitius, Koch, Morinus, Topocentric, Sripati, Vehlow, Horizon/Azimuth, Krusinski-Pisa-Goelzer, Sunshine, Sunshine alternative, Savard-A, Pullen SD, Pullen SR, Carter, APC, Equal MC, Natural, and Gauquelin are calculation-only and are not saved-profile options. Select the exact documented system value. See the beta guide for conventions and limitations.

Example Request (Sidereal)

{
  "birth": {
    "date": "1990-01-01",
    "time": "12:00",
    "timezone": "UTC",
    "lat": 40.7128,
    "lon": -74.0060
  },
  "system": "equal",
  "zodiac": "sidereal",
  "ayanamsa": "lahiri"
}

Example Response

This verified response is abbreviated and numerically rounded. Gateway-added and chart fields are returned at the top level.

{
  "type": "houses",
  "house_system": "equal",
  "status": "ok",
  "zodiac": "sidereal",
  "ayanamsa": "lahiri",
  "planets": {
    "Sun": { "lon": 257.0968, "tropical_lon": 280.8143, "sign": "Sagittarius" },
    "Moon": { "lon": 309.5503, "tropical_lon": 333.2677, "sign": "Aquarius" }
  },
  "houses": {
    "ascendant": 250.9224,
    "mc": 185.1975,
    "systems": {
      "equal": {
        "name": "Equal",
        "houses": { "1": 250.9224, "2": 280.9224 }
      }
    }
  },
  "aspects": [
    {
      "p1": "Sun",
      "p2": "Mars",
      "type": "semisextile",
      "exact_angle": 30,
      "distance": 30.8141,
      "orb": 0.8141
    }
  ],
  "nodes": {
    "mean": {
      "longitude": 294.7143,
      "sign": "Capricorn",
      "deg_in_sign": 24.7143
    }
  },
  "metadata": {
    "note": "Geocentric positions using JPL DE421 ephemeris."
  }
}

Quick Test / curl

Use this curl command to quickly test the Sidereal Houses API endpoint with your API key:

curl -i https://api.cosmicephemeris.com/api/astro/houses \
  -X POST \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer ${COSMICEPHEMERIS_KEY}" \
  -d '{
    "birth": {
      "date": "2000-01-01",
      "time": "12:00",
      "timezone": "America/New_York",
      "lat": 33.7488,
      "lon": -84.3877
    },
    "system": "equal",
    "zodiac": "sidereal",
    "ayanamsa": "lahiri"
  }'

Common Uses

  • Sidereal chart wheel rendering
  • House-based analytics
  • Synastry overlays
  • Coordinate-system comparison
  • Advanced astrology dashboards

This API provides raw calculation data only; interpretation, scoring, and compatibility logic are handled client-side.

Lahiri is the default; the eleven documented ayanamsas are supported. House angles use date-dependent true obliquity and apparent sidereal time. Exact geographic poles and undefined Ascendant geometry return HTTP 400. Public dates are limited to 1900-01-01 through 2050-12-31. 

// Node.js 22+ — server-side only
fetch("https://api.cosmicephemeris.com/api/astro/houses", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "Authorization": `Bearer ${process.env.COSMICEPHEMERIS_KEY}`
  },
  body: JSON.stringify({
    birth: {
      date: "1990-01-01",
      time: "12:00",
      timezone: "America/New_York",
      lat: 40.7128,
      lon: -74.0060
    },
    system: "equal",
    zodiac: "sidereal",
    ayanamsa: "lahiri"
  })
})
  .then(res => res.json())
  .then(data => console.log(data));
# Python — Sidereal Houses API
import os
import requests

url = "https://api.cosmicephemeris.com/api/astro/houses"

payload = {
  "birth": {
    "date": "1990-01-01",
    "time": "12:00",
    "timezone": "America/New_York",
    "lat": 40.7128,
    "lon": -74.0060
  },
  "system": "equal",
  "zodiac": "sidereal",
  "ayanamsa": "lahiri"
}

headers = {
  "Content-Type": "application/json",
  "Authorization": f"Bearer {os.environ['COSMICEPHEMERIS_KEY']}"
}

response = requests.post(url, json=payload, headers=headers)
print(response.json())