GET /v1/midpoints — Midpoints of every body pair, antiscia, Arabic lots, and Cosmobiology midpoint trees.

Midpoints & Derived Points

Points derived from bodies rather than observed: the midpoint of every body pair, each body's antiscion and contra-antiscion, optionally the Arabic lots, and — on request — midpoint trees on a dial. Location is optional; with it every point gets a house placement and lots become available.

Text

GET  /v1/midpoints
POST /v1/midpoints

Credit cost: 1

The same points are available inside any chart response by adding derived_points=true to /v1/natal-chart, /v1/synastry, /v1/davison, /v1/progressed, /v1/draconic, or /v1/returns. The flag costs nothing extra.

Parameters

Parameter	Type	Required	Default	Description
`datetime`	string	One of `datetime` or `jd`	—	ISO 8601 UTC datetime
`jd`	number	One of `datetime` or `jd`	—	Julian Day in UT1
`bodies`	string	No	`"planets"`	Comma-separated body names
`sidereal`	string	No	—	Ayanamsha for sidereal mode
`lat`, `lon`	number	Only for `lots`	—	Observer location; enables house placement and lots
`system`	string	No	`"placidus"`	House system when `lat`/`lon` are given
`midpoints`	boolean	No	`true`	Midpoint of every body pair
`antiscia`	boolean	No	`true`	Antiscion and contra-antiscion of every body
`lots`	string	No	none	Comma-separated lot names, or `default` for the seven Hermetic lots; requires `lat`/`lon`
`resolution`	string	No	`"lower"`	Which candidate wins when two bodies are exactly 180° apart: `"lower"` or `"higher"` longitude
`trees`	boolean	No	`false`	Also build midpoint trees
`modulus`	number	No	`90`	Dial modulus for trees: `360` (conjunctions to midpoints), `90` (the Cosmobiology dial), `45` (the Uranian dial)
`tree_orb`	number	No	`1.5`	Maximum dial orb for a tree hit (0–15)

Response

JSON

{
  "data": {
    "derived_points": [
      { "kind": "midpoint", "name": "sun/moon", "constituents": ["sun", "moon"], "longitude": 296.52, "sign": "Capricorn", "sign_degree": 26.52, "house": 10 },
      { "kind": "antiscion", "name": "sun", "constituents": ["sun"], "longitude": 235.31, "sign": "Scorpio", "sign_degree": 25.31, "house": 8, "declination": -21.04 },
      { "kind": "contra_antiscion", "name": "sun", "constituents": ["sun"], "longitude": 55.31, "sign": "Taurus", "sign_degree": 25.31, "house": 2, "declination": 21.04 },
      { "kind": "lot", "name": "Fortune", "constituents": ["moon", "sun", "ascendant"], "longitude": 12.87, "sign": "Aries", "sign_degree": 12.87, "house": 1 }
    ],
    "trees": [
      {
        "body": "sun",
        "longitude": 304.69,
        "modulus": 90,
        "hits": [
          { "constituents": ["venus", "saturn"], "longitude": 34.12, "orb": 0.57 }
        ]
      }
    ]
  },
  "meta": { "credits_used": 1, "...": "..." }
}

Field	Description
`kind`	`midpoint`, `antiscion`, `contra_antiscion`, or `lot`
`name`	`"a/b"` for a midpoint, the body for antiscia, the lot's name
`constituents[]`	The bodies the point is built from; a lot lists `[body_a, body_b, "ascendant"]`
`longitude`, `sign`, `sign_degree`	Ecliptic position, like a body's
`house`	House placement when `lat`/`lon` were given
`declination`	An antiscion shares its body's declination, a contra-antiscion negates it; midpoints and lots have none
`trees[]`	Present when `trees=true`: one per selected body, `hits` sorted tightest first; a body with no hits still has a tree

How the points are formed

A midpoint is always the shortest-arc midpoint. resolution only matters when the two bodies are exactly 180° apart, where both candidates are equally short.
An antiscion is the reflection across the 0° Cancer / 0° Capricorn axis — 180° − λ — so the Sun at 25° Capricorn has its antiscion at 5° Sagittarius. It keeps the body's declination, which is the point of the construction: two bodies in antiscia share the same declination. A contra-antiscion reflects across 0° Aries / 0° Libra (−λ) and negates the declination.
Lots use the same formulas and day/night detection as /v1/lots.
A midpoint tree lists, for one body, every midpoint of other pairs that falls within tree_orb of it on the dial. On the 90° dial, "on the dial" means conjunct, square, or opposite in the zodiac; on the 45° dial the semi-squares join in.

Examples

Every midpoint and antiscion for the planets

Bash

curl "https://api.morphemeris.com/v1/midpoints?datetime=1990-06-15T18:30:00Z" \
  -H "Authorization: Bearer morphemeris_live_YOUR_KEY"

javascript

const res = await fetch(
  "https://api.morphemeris.com/v1/midpoints?datetime=1990-06-15T18:30:00Z",
  { headers: { Authorization: "Bearer morphemeris_live_YOUR_KEY" } },
);
const { data } = await res.json();
const sunMoon = data.derived_points.find((p) => p.name === "sun/moon");
console.log(sunMoon.sign, sunMoon.sign_degree.toFixed(2));

Midpoint trees on the 90° dial, with houses and lots

Bash

curl "https://api.morphemeris.com/v1/midpoints?datetime=1990-06-15T18:30:00Z&lat=40.7128&lon=-74.006&lots=default&trees=true" \
  -H "Authorization: Bearer morphemeris_live_YOUR_KEY"

Errors

Code	Cause
`missing_parameter`	`lots` without `lat` and `lon`
`invalid_parameter`	Unknown `resolution`, `modulus` outside (0, 360], `tree_orb` outside 0–15, or an unknown lot name

Midpoints & Derived Points

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