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Data Sources

Primary source: Space-Track.org

All GP/TLE element sets come from Space-Track.org, the public catalog maintained by the 18th Space Defense Squadron (18 SDS) of the United States Space Command (USSPACECOM).

Space-Track provides General Perturbations (GP) data — the mathematical models that describe satellite orbits. Each element set contains the orbital parameters needed to predict a satellite's position using SGP4/SDP4 propagators.

Data types

GP element sets (TLE/OMM)

The core data product. Each record describes a satellite's orbit at a specific epoch:

  • Keplerian elements: inclination, eccentricity, RAAN, argument of perigee, mean anomaly, mean motion
  • Drag terms: B* coefficient, mean motion derivatives
  • Metadata: NORAD catalog ID, international designator, classification, element set number

These are published in two equivalent representations:

  • TLE (Two-Line Element): legacy fixed-width text format, widely supported
  • OMM (Orbit Mean-elements Message): modern CCSDS standard, supports JSON/XML/KVN

SATCAT (Satellite Catalog)

Metadata about each tracked object:

  • Object name, type (payload, rocket body, debris)
  • Owner/operator country
  • Launch date and site
  • Operational status
  • Decay date (if applicable)

Historical coverage

Metric Value
Coverage period 2004 to present
Total element sets ~167 million
Cataloged objects ~68,000 (SATCAT)
Active satellites ~27,000 (with current GP)
Update cadence Daily (GP history archived, current GP refreshed)

Data quality notes

  • TLE format limitations: The traditional TLE format cannot represent NORAD catalog IDs above 99,999. For newer objects with higher IDs, use JSON, XML, KVN, or CSV formats.
  • Duplicate handling: Space-Track occasionally publishes multiple element sets with the same epoch for an object. We deduplicate by keeping the most recently published version.
  • Epoch gaps: Some objects have irregular tracking cadence. Gaps in element set availability are normal, especially for debris and objects in highly elliptical orbits.
  • Derived fields: PERIOD_MINUTES, APOGEE_KM, PERIGEE_KM, and SEMI_MAJOR_AXIS_KM are computed from the mean elements. These are approximate and assume a spherical Earth (WGS-84 equatorial radius).

Required citation

When using data from the Orbital Data API, you must cite the original source:

Data Attribution

Source: USSPACECOM via Space-Track.org

Per Space-Track's terms of use, all users of derived data must acknowledge the original source.

See Attribution for full details.