Alpha-5

TLE's Alpha-5 Format


SOLARAS
1 A0081U 26164B   26217.35875216  .00020569  00000-0  50367-3 0  9999
2 A0081  59.9235 234.1125 0008817 331.6092  28.4513 15.40791267  2782

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Changes to AMSAT_TLE Distribution for July 31, 2026, (C)AMSAT-News

Two Line Elements or TLEs, often referred to as Keplerian elements or keps
in the amateur community, are the inputs to the SGP4 standard mathematical
model of spacecraft orbits used by most amateur tracking programs. Weekly
updates are completely adequate for most amateur satellites. TLE bulletin
files are updated daily in the first hour of the UTC day. New bulletin
files will be posted immediately after reliable elements become available
for new amateur satellites. More information may be found at
https://www.amsat.org/keplerian-elements-resources/

There are no changes to this week's TLE distribution.
General Perturbations Data Support

AMSAT is pleased to announce that modern forms of what are called General
Perturbations data are being disseminated via modern formats including
JSON, XML and KVN at https://newark192.amsat.org/gpdata/current/. The
reason this change is being made is that we are running out of 5-digit
catalog numbers and the TLE format is not viable for satellites launched
after July of this year. See
https://celestrak.org/NORAD/documentation/gp-data-formats.php for details.

These data are presently considered in beta test for the next two months
while hosted on the test server newark192.amsat.org, and we are very open
to community feedback at webmaster at amsat.org. Testers may experience
outages and errors while we make improvements. We intend to put this into
production on our main web server in July as we expect that satellites
launched after this summer will require one of the new formats to
accommodate longer object numbers. AMSAT will continue to publish TLE
bulletins for satellites launched before July 2026 indefinitely.

[ANS thanks Joe Fitzgerald, KM1P, AMSAT Orbital Elements Manager,
 for the above information]

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Add Alpha-5 catalog number support (Gpredict), (C)GitHub

CelesTrak's SATCAT crossed 100000 on 2026-07-11, so newly cataloged objects
now use 6-digit numbers that don't fit the TLE format's 5-character catalog
number field. Space-Track/CelesTrak's stopgap is Alpha-5 encoding, which
replaces the leading digit with a letter (A-Z, excluding I/O) to represent
numbers up to 339999.

Gpredict parses the catalog number field with a plain numeric conversion in
two places (sgp_in.c's Convert_Satellite_Data and tle-update.c's read_fresh_tle),
so any Alpha-5 catalog number silently decoded to 0. This adds an Alpha-5-aware
decoder used in both spots, handling the legacy all-numeric format (zero- or
space-padded) as well as Alpha-5.

Verified against Space-Track's published Alpha-5 test values
(A0000->100000 ... Z9999->339999) plus legacy zero- and space-padded low
catalog numbers.

Both SpaceTrack and Celestrack offer Alpha-5 TLE formatted tle as a bridge
for legacy parsers. In addition to the TLE/3LE/2LE (legacy, Alpha-5 encoded
for 6+ digit numbers), they also offer JSON, XML, CSV and KVN formats.
SpaceTrack also offers HTML! However, AMSAT skipped right over Alpha-5.
It appears that at present they only offer GP data in JSON, XML, and KVN
formats via newark192.amsat.org (beta). As well as TLE for older sats.
No mention of CSV.