Satellites and TLEs

Select satellites

Satellites → Select satellites opens a list of spacecraft from the TLE catalogue. Tick only the ones you want on the map and in the pass list. Too many satellites can make the map busy.

TLEs (orbital data)

Pass times and positions come from Two-Line Elements. By default OscarWatch downloads them from tle.oscarwatch.org and caches a copy under %AppData%\OscarWatch\tle-cache.txt.

• Settings → TLE — use the OscarWatch JSON GP feed (default), the AMSAT.org JSON GP bulletin, a custom URL (JSON or classic TLE), or a local file you maintain yourself.
• Satellites → Refresh TLEs — download or re-read the catalogue now.
• Settings → TLE → TLE updates — choose when to refresh automatically (URLs only; e.g. on startup, every six hours).
• The status bar shows how long ago TLEs were updated and which source is in use (e.g. “TLE 2 h ago (tle.oscarwatch.org)”).
• Classic TLE/3LE Alpha-5 catalogue fields (objects 100000–339999, e.g. A0000) are accepted automatically. JSON GP feeds keep numeric NORAD_CAT_ID; OscarWatch encodes them to Alpha-5 only when rewriting fixed-width TLE lines for the propagator.

Transponder database

Frequencies and modes are stored separately from TLEs, in your user database:

%AppData%\OscarWatch\satellite_database.json

Satellites → Manage transponder database lets you add satellites (pick a name from your TLE catalog or type a custom name), edit uplink/downlink frequencies in kHz, set mode names, Doppler type (normal or reverse), and CTCSS tones. Changes are saved to your AppData copy, not the application installation folder.

Preferred names and alternative names

Many spacecraft have more than one common name (for example UmKA-1 and RS40-S). In the editor you can set:

• Preferred name — the label shown on the map, pass list, and frequency panel. Renaming here updates the map as soon as you save and close the editor.
• NORAD ID — the stable catalogue number. Use this whenever you can; OscarWatch prefers it when matching TLEs and when merging published database updates.
• Alternative names — comma-separated nicknames or older catalogue names used for matching. Renaming a satellite automatically keeps the previous preferred name in this list so the next Update transponder database… does not treat the published name as a new spacecraft.

Example: preferred name UmKA-1 (RS40-S), NORAD ID filled in, alternative names UmKA-1, RS40-S. The map shows your preferred label; sync and frequency lookup still find the entry via NORAD or those aliases.

OscarWatch publishes an updated transponder list at tle.oscarwatch.org/satellite_database.json. Use Satellites → Update transponder database… (or Check for updates in the editor) to download and merge new satellites and modes. In the editor, Import JSON… and Export JSON… use a file picker for backups or sharing; import opens the same merge dialogue as remote updates (press Save in the editor to keep changes).

• Settings → Tracking — enable Check for transponder database updates on startup (on by default; this is separate from the TLE catalog source).
• New remote entries are selected by default in the merge dialogue; uncheck any you do not want.
• If a mode you already have differs from the published copy, choose Use local version and press Apply selected to confirm your edit (you will not be asked again unless you change the frequency or the published database changes). Choose Use published version to adopt the server copy instead.
• Merge matches your local entry by NORAD ID first, then by preferred name or any alternative name. Your preferred name is kept; published updates add modes without renaming the satellite on your map.
• Restore defaults reloads the database shipped with your app version, not the remote file.
• Set uplink to 0 for receive-only modes (SSTV, beacons, telemetry).