---
title: "Historical timezone overlay coverage report"
method: GET
path: "/timezone/coverage"
tags: ["location-timezone"]
---

# Historical timezone overlay coverage report

`GET /timezone/coverage`

## Request

- Base URL: `https://api.openephemeris.com`
- URL: `https://api.openephemeris.com/timezone/coverage`
- Auth: HTTP bearer

Machine-generated report of what the historical-timezone correction overlay covers and what it does not. Regenerated from the same overlay.json used at request time, so it cannot drift from the live dataset.

`covered` lists every overlay row (region, local date range, zones, offsets, and its `precision` sourcing grade: 'statutory', 'documented', or 'inferred'). `gaps` lists, per region the overlay claims any coverage for, the uncovered date spans inside 1883-11-18 to 1970-01-01. Everything outside the polygons in `covered`, for every date, is uncovered by construction and is not separately enumerated.

Poll `overlay_version`/`overlay_hash` the same way as the `tz_overlay_version`/`tz_overlay_hash` fields on `/timezone/offset` — they move together.

## Headers

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

## Response `200`

Successful Response

- object

## Other responses

- `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)