---
title: "Equation of Time"
method: GET
path: "/time/equation-of-time"
tags: ["Time Conversion"]
---

# Equation of Time

`GET /time/equation-of-time`

## Request

- Base URL: `https://api.openephemeris.com`
- URL: `https://api.openephemeris.com/time/equation-of-time`
- 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`

Compute the Equation of Time (sundial correction) in minutes for a given JD.

## Query parameters

- `jd` number, double, required: Julian Day (Terrestrial Time)

## Headers

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

## Response `200`

Successful Response

- EquationOfTimeResponse
  - `apparent_solar_time` number, required: The computed Apparent Solar Time (decimal hours)
  - `equation_of_time_minutes` number, required: The Equation of Time value in minutes
  - `julian_day` number, double, required: The Julian Day (TT) used for calculation
  - `mean_solar_time` number, required: The computed Mean Solar Time (decimal hours)

## 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)