Two-Line Element (TLE)

Table of contents
  1. Overview
  2. Viewing the TLE
  3. Modifying the TLE
  4. Retrieving a TLE from CelesTrak
    1. Mode 1 — Search by Satellite Name
    2. Mode 2 — Look Up by Catalog Number
    3. Mode 3 — Manual Entry
  5. Exporting / Copying the TLE
  6. Permissions Summary

Overview

A Two-Line Element set (TLE) is a standardised NASA/NORAD data format that describes the orbital parameters of a satellite at a specific epoch. In EORSA-DB, each System (satellite) can have one associated TLE record used to document its current orbit and enable integration with external orbital simulation software.

The TLE record has two fields:

Field Description
Catalog Number The NORAD/COSPAR satellite catalog number (integer). Uniquely identifies the object in space surveillance catalogs.
Current Value The full two-line element string — two lines of exactly 69 characters each, as issued by Space-Track.org or Celestrak.

Viewing the TLE

  1. Open the Data page and select System in the subject dropdown.
  2. Click on a system row to open its detail page.
  3. Scroll to the Two-Line Element section.

The section displays the current Catalog Number and the two-line string.

Screenshot of a System detail page with the Two-Line Element section visible, showing the Catalog Number and two-line text

Modifying the TLE

Modifying a TLE requires the ModifyCoreData permission.

  1. Open the system’s detail page (see Viewing the TLE above).
  2. In the Two-Line Element section, click the Edit button (pencil icon).
  3. The TLE Reference Dialog opens. Choose a retrieval mode:
    • Name — search CelesTrak by satellite name and select from results.
    • Catalog Number — look up by NORAD number directly from CelesTrak.
    • Manual — enter the catalog number and TLE text by hand.
  4. Click Save to confirm the changes.

See Retrieving a TLE from CelesTrak for full details on each mode.

Screenshot of the TLE Reference Dialog as opened from the Edit button, showing the Mode dropdown with Name/Catalog Number/Manual options

Retrieving a TLE from CelesTrak

EORSA-DB includes a built-in integration with the CelesTrak GP data API. When editing a TLE, the application can automatically fetch the latest orbital data for a satellite — no external login or manual copy-paste required.

When you click Edit (or Add) on the TLE section of a System, a dialog opens with three modes:

Mode 1 — Search by Satellite Name

Use this mode if you know the satellite’s name but not its NORAD catalog number.

  1. Select Name in the Mode dropdown.
  2. Type the full or partial satellite name in the Satellite Name field (e.g., Sentinel-3A).
  3. Click Search. The app queries CelesTrak and returns a list of matching satellites.
  4. Select the correct satellite from the Search Results dropdown.
  5. The Catalog Number and TLE content are populated automatically.
  6. Click Save (or Add).

Screenshot of the TLE Reference Dialog in Name mode, showing the satellite name search box, Search button, and the search results dropdown with a satellite selected

Mode 2 — Look Up by Catalog Number

Use this mode if you already know the satellite’s NORAD catalog number.

  1. Select Catalog Number in the Mode dropdown.
  2. Enter the NORAD catalog number in the Catalog Number field (e.g., 39634 for Sentinel-3A).
  3. Click Look Up. The app queries CelesTrak and displays the found record.
  4. If found, a success banner shows the satellite name and TLE preview.
  5. If not found, a warning banner indicates no record exists for that number.
  6. Click Save (or Add).

Screenshot of the TLE Reference Dialog in Catalog Number mode, showing the catalog number input field, Look Up button, and the success alert showing the found TLE record

Mode 3 — Manual Entry

Use this mode to enter TLE data manually (e.g., from a different catalog source).

  1. Select Manual in the Mode dropdown.
  2. Enter the Catalog Number (integer).
  3. Paste the TLE text into the TLE Content field.
  4. Click Save (or Add).

A valid TLE consists of exactly two lines of 69 characters each (lines 1 and 2). Do not include the name line (line 0) in the TLE Content field.

Exporting / Copying the TLE

To use the stored TLE in external orbital simulation software (e.g., STK, GMAT, Orekit):

  1. Open the system’s detail page.
  2. Navigate to the Two-Line Element section.
  3. Click on the Current Value text to select it, then copy it to the clipboard.
  4. Paste it into the external software’s TLE input field.

The TLE Current Value is a plain-text two-line string compatible with any tool that accepts the standard NORAD/NASA TLE format.

Permissions Summary

Action Required Permission
View TLE AccessOtherDataButProgrammatics
Edit TLE ModifyCoreData