---
title: "Time Scale Conversions"
method: POST
path: "/time/scales"
tags: ["Time Conversion"]
---

# Time Scale Conversions

`POST /time/scales`

## Request

- Base URL: `https://api.openephemeris.com`
- URL: `https://api.openephemeris.com/time/scales`
- Auth: one of:
  - HTTP bearer
  - API key in header `X-OpenEphemeris-API-Key`
  - API key in header `X-API-Key`
  - API key in header `X-Service-Key`

Convert between major astronomical time scales (UTC, TT, TAI, TDB, UT1).

## Headers

- `authorization` string, nullable
- `X-API-Key` string, nullable
- `X-OpenEphemeris-API-Key` string, nullable
- `apikey` string, nullable

## Request body

- TimeScalesRequest
  - `from_scale` string: Input time scale (utc, tt, tai, tdb, ut1)
  - `julian_day` number, double, required: Julian Day to convert
  - `latitude` number: Observer latitude
  - `longitude` number: Observer longitude

## Response `200`

Successful Response

- TimeScalesResponse
  - `delta_t` number, required: Delta T value used (seconds)
  - `jd_tai` number, double, required: Julian Day in International Atomic Time
  - `jd_tdb` number, double, required: Julian Day in Barycentric Dynamical Time
  - `jd_tt` number, double, required: Julian Day in Terrestrial Time
  - `jd_ut1` number, double, required: Julian Day in Universal Time 1
  - `jd_utc` number, double, required: Julian Day in Coordinated Universal Time
  - `offsets_seconds` object, required: Offsets in seconds between scales relative to TT

## Other responses

- `400`: Bad Request
- `422`: Validation Error
- `500`: Internal Server Error

---

[API](https://skmtc.dev/openephemeris/apis/open-ephemeris-api.md) · [All operations](https://skmtc.dev/openephemeris/apis/open-ephemeris-api/llms.txt) · [OpenAPI document](https://skmtc.dev/openephemeris/apis/open-ephemeris-api/revisions/d195a769cb89?raw)