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Timestamps Extension Specification

This document explains the fields of the Timestamps Extension to all STAC entities. Allows to specify numerous timestamps for assets and metadata in addition to created, updated and datetime (incl. start and end).


The fields in the table below can be used in these parts of STAC documents:

  • Catalogs
  • Collections
  • Item Properties (incl. Summaries in Collections)
  • Assets (for both Collections and Items, incl. Item Asset Definitions in Collections)
  • Links
Field Name Type Description
published string Date and time the corresponding data (see below) was published the first time, in UTC.
expires string Date and time the corresponding data (see below) expires (is not valid any longer), in UTC.
unpublished string Date and time the corresponding data (see below) was unpublished, in UTC.

All timestamps MUST be formatted according to RFC 3339, section 5.6.

NOTE: The timestamps have different meaning depending on where they are used. If those fields are available in a Collection, in a Catalog (both top-level), or in a Item (in the properties), the fields refer the metadata (e.g., when the STAC metadata was published). Having those fields in the Assets or Links, they refer to the actual data linked to (e.g., when the asset was published).


An overview over the lifecycle of data and their corresponding timestamps:

  1. Data capture, start: start_datetime
  2. Data capture, often center: datetime
  3. Data capture, end: end_datetime
  4. Data first modified (stored): created
  5. Data last modified: updated
  6. Data first published: published
  7. Data last published: N/A
  8. Data valid until: expires
  9. Data removed / unpublished: unpublished


All contributions are subject to the STAC Specification Code of Conduct. For contributions, please follow the STAC specification contributing guide Instructions for running tests are copied here for convenience.

Running tests

The same checks that run as checks on PR's are part of the repository and can be run locally to verify that changes are valid. To run tests locally, you'll need npm, which is a standard part of any node.js installation.

First you'll need to install everything with npm once. Just navigate to the root of this repository and on your command line run:

npm install

Then to check markdown formatting and test the examples against the JSON schema, you can run:

npm test

This will spit out the same texts that you see online, and you can then go and fix your markdown or examples.

If the tests reveal formatting problems with the examples, you can fix them with:

npm run format-examples