---
title: "Phase Return"
method: POST
path: "/phase-return"
tags: ["Astro-Geography"]
---

# Phase Return

`POST /phase-return`

Find dates when a planet returns to its same synodic phase relative to the Sun (e.g. next Venus heliacal rising, next Mars retrograde station).

## Request body

- PhaseReturn — Birth data for a single natal chart. Required: date (YYYY-MM-DD), time (HH:mm:ss). Coordinates are latitude and longitude in decimal degrees, plus timezoneOffset in hours from UTC; the short forms lat, lon, lng and tz are rejected with 400 INVALID_FIELD. Omitting the coordinates is not the same as skipping them: houses, angles and everything derived from them are then computed for 0°N 0°E at UTC, which is a wrong answer rather than a neutral default.
  - `date` string, required
  - `time` string, required
  - `timezoneOffset` number, nullable
  - `latitude` number, nullable
  - `longitude` number, nullable
  - `houseSystem` string
  - `name` string
  - `city` string
  - `zodiacType` 'tropical' | 'sidereal'
  - `ayanamsaId` number, nullable
  - `cosmogram` boolean
  - `startYear` number, nullable, required
  - `endYear` number, nullable, required

## Response `200`

Successful calculation

- object
  - `ok` boolean
  - `data` object
    - `planet` string, nullable
    - `phase` string, nullable
    - `returns` object[], nullable
      - `date` string, nullable
      - `longitude` number, nullable

## Other responses

- `400` — Validation error
- `401` — Missing or invalid API key

---

[API](https://skmtc.dev/astroway/apis/astroway-calculation-api.md) · [All operations](https://skmtc.dev/astroway/apis/astroway-calculation-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/astroway/astroway-calculation-api/revisions/793e5c2dbcdf/schema)