URGENT: We ran out of 5-digit catalog numbers with the addition of Saramago on 2026-07-11. We had estimated that to occur around 2026‑07‑12 back on 2026-05-09. The official USSF SATCAT is now at 100000. All newly cataloged objects will have 6-digit catalog numbers of 100000+ and GP data will not be available for them using the TLE format.
CelesTrak developed new formats that removed the 5-digit catalog number limitation (and finally fixed the Y2K problem) in May 2020 and immediately began providing GP data in those formats for software developers. Please be sure to adhere to our usage policy when retrieving any CelesTrak data. The same limitations apply to the legacy fixed-field SATCAT. That legacy format will continue to update but will only contain data for objects with catalog numbers below 70000. Be sure to follow @TSKelso on Bluesky for the latest updates, tutorials, and changes as we move forward. Spread the word!
Source: https://www.celestrak.org/NORAD/elements/
Alpha-5 is a stopgap object numbering schema from the United States Space Force that increases the satellite catalog’s capacity to display up to 339,999 objects in the GP/GP_History API classes using legacy fixed-width Two and Three Line Element Set (TLE/3LE) formats.
Replacing the 1st digit of the 5-digit object number with an alphanumeric character makes it possible to represent 240,000 more numbers. Objects less than 100,000 are unaffected by Alpha-5, as are users who download elsets from the GP and GP_History API classes in other formats like XML, JSON, KVN, and CSV. In order to preserve legacy operations that depend on 5-digit integers, our legacy API Classes tle, tle_latest, and tle_publish will not change to Alpha-5.
Only capital letters and numbers are used in Alpha-5. The letters “I” and “O” are omitted to avoid confusion with the numbers “1” and “0”.
Source: https://www.space-track.org/documentation#tle-alpha5























