---
title: "Cyclic Index"
method: POST
path: "/cyclic-index"
tags: ["Calendar & Cycles"]
---

# Cyclic Index

`POST /cyclic-index`

Calculate the André Barbault Cyclic Index, sum of all outer planet separations, for a date range to indicate global crisis periods.

## Request body

- CyclicIndex
  - `startYear` number, nullable, required
  - `endYear` number, nullable, required
  - `pairs` unknown

## Response `200`

Successful calculation

- object
  - `ok` boolean
  - `data` object
    - `startYear` number, nullable
    - `endYear` number, nullable
    - `count` number, nullable
    - `data` object[], nullable
      - `jd` number, nullable
      - `year` number, nullable
      - `total` number, nullable
      - `pairs` object, nullable
        - `Jupiter-Saturn` number, nullable
        - `Jupiter-Uranus` number, nullable
        - `Jupiter-Neptune` number, nullable
        - `Jupiter-Pluto` number, nullable
        - `Saturn-Uranus` number, nullable
        - `Saturn-Neptune` number, nullable
        - `Saturn-Pluto` number, nullable
        - `Uranus-Neptune` number, nullable
        - `Uranus-Pluto` number, nullable
        - `Neptune-Pluto` number, nullable

## Other responses

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

## Changes

- **2026-08-24** `8ab5a768b521` — 3 warning, 7 info
  - removed the optional property `data/data/items/date` from the response with the `200` status
  - removed the optional property `data/data/items/index` from the response with the `200` status
  - removed the optional property `data/minimum` from the response with the `200` status
  - added the optional property `data/count` to the response with the `200` status
  - …6 more

[Change history](https://skmtc.dev/astroway/apis/astroway-calculation-api/changes/cyclic-index/post.md)

---

[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/8ab5a768b521/schema)