Repost from ANS-200 but very important to repeat:
The U.S. Space Force’s authoritative satellite catalog entered a new era on July 11, 2026, when newly assigned catalog numbers advanced from the five-digit sequence ending at 69,999 directly to six-digit catalog number 100,000. Space-Track announced the change and advised users to review its Alpha-5 information and frequently asked questions to ensure that Two-Line Element (TLE) and Three-Line Element (3LE) parsers, along with API queries, remain compatible with the expanded numbering system. The milestone marks the beginning of permanent six-digit catalog numbers for newly cataloged space objects.
The milestone was reached with the cataloging of Saramago, also known as Lusíada 3, one of four Portuguese communications satellites developed by LusoSpace. Named in honor of Nobel Prize-winning author José Saramago, the satellite is part of the Lusíada constellation, which uses Automatic Identification System (AIS) and VHF Data Exchange System (VDES) technology to improve maritime safety, vessel tracking, weather reporting, and ocean data services. The transition occurred one day earlier than CelesTrak had predicted.
Although the traditional TLE format has served the satellite community for decades, its fixed-field design was never intended to accommodate six-digit catalog numbers. Space-Track is maintaining compatibility through its Alpha-5 encoding system, while CelesTrak will distribute General Perturbations (GP) data for catalog numbers 100,000 and above using modern formats such as JSON, XML, CSV, and Key-Value Notation (KVN). These newer formats also eliminate the long-standing two-digit year limitation inherited from the legacy TLE format.
CelesTrak began supporting the modern GP formats in May 2020, giving software developers several years to prepare for the eventual transition. AMSAT likewise anticipated the change by introducing GP data distribution through its Orbital Elements service. Joe Fitzgerald, KM1P, AMSAT Orbital Elements Manager, announced that AMSAT would provide orbital elements in JSON, XML, and KVN formats while continuing to publish traditional TLE bulletins indefinitely for satellites cataloged before the six-digit transition.
For most amateur satellite operators, the change will be largely transparent when tracking existing satellites. However, software that assumes all catalog numbers contain no more than five numeric digits may require updates before it can process newly cataloged spacecraft. Developers and operators of satellite tracking applications, automated ground stations, and custom scripts are encouraged to verify compatibility with Alpha-5 encoded TLEs or one of the newer GP data formats.
While the transition may appear to be a simple numbering change, it represents one of the most significant updates to satellite orbital data distribution in decades. As launch rates continue to increase and the number of tracked satellites and debris objects grows, six-digit catalog numbers and modern orbital data formats will ensure the U.S. Space Force’s authoritative satellite catalog continues to support both the amateur and professional space communities for years to come.
### For More Information
AMSAT General Perturbations data:
https://newark192.amsat.org/gpdata/current/
CelesTrak General Perturbations data formats:
https://celestrak.org/NORAD/documentation/gp-data-formats.php
Space-Track Alpha-5 information and frequently asked questions:
https://www.space-track.org/
[ANS thanks Joe Fitzgerald, KM1P, AMSAT Orbital Elements Manager, Dr. T.S. Kelso of CelesTrak, and Space-Track for the above information]