gp-omm-conformance

A conformance corpus for orbital-data parsers crossing the five-digit catalog-number boundary: Alpha-5 TLEs, six- and nine-digit NORAD_CAT_IDs, and the CCSDS Orbit Mean-Elements Message (OMM) in CSV, JSON, XML and KVN, as actually served by CelesTrak.

It answers one question for a developer: does my parser survive the migration? You point it at your parser; it tells you, case by case, what breaks and why, with every expected value traceable to a provider response whose URL, retrieval time and SHA-256 are recorded. One case (tle-writer-alpha5) asks the same of code that writes TLEs: Alpha-5 in the catalog field, valid lines, and a refusal for the numbers the format cannot carry.

Status: version 0.3.0, a minor release: the runner and the corpus install with pip as gpconf, with presets that test a library without an adapter and a GitHub Action, and the adapter protocol gains a refusal channel, an additive change; the seventeen cases stay, no frozen expected value changed (the writer case gained one input), and the naive and python-sgp4 adapters still fail 14 and 7 of them. The independent audit (AUDIT.md) covered v0.1.0; neither the writer-side case of v0.2.0, the fixes of v0.2.1 nor the packaging and protocol changes of v0.3.0 have been separately audited. Maintainer: Honorius Neogy (NEOGY LLC).

See DECISIONS.md for the full decision log and MANIFEST.md for every case, source and known gap.

The migration in one page

What changed. On 2026-07-11 the US Space Force catalog assigned number 100000 (to the Portuguese CubeSat SARAMAGO) after exhausting the five-digit range, which ends at 69999 (CelesTrak). Of the 70000-99999 block, primary sources describe only 80000-89999, the analyst range (Space-Track); what the rest of the block is used for is reported by secondary sources only. Every object catalogued since has a six-digit number. The fixed-width TLE format has room for five characters, so two coexisting answers exist:

• Alpha-5 (US Space Force stopgap; Space-Track serves it, CelesTrak does not): the first digit is replaced by a letter, A=10 ... Z=33 with I and O skipped, so 100000 becomes A0000 and the ceiling is 339999. Only TLE/3LE lines carry it.
• OMM (CCSDS 502.0-B-3, served by CelesTrak since May 2020 and by Space-Track's GP class): NORAD_CAT_ID is an integer of up to nine digits; four-digit years; no fixed widths.

What CelesTrak does. It emits no Alpha-5 at all. A TLE/3LE/2LE request returns only the objects below 100000; if none qualify (today, any group of recent launches) the response is HTTP 404 with the body No GP data found. The OMM formats return everything. CelesTrak's default format has been CSV since 2026-05-09.

What breaks (each item is a corpus case; see docs/FAILURES.md for the evidence):

1. int() on TLE columns 3-7, or any five-character assumption about the catalog number.
2. Treating an empty TLE file or a 404 as "no new data" and silently losing every object launched after 2026-07-11.
3. Requiring OBJECT_ID: analyst objects have an empty one in every format, and Python's ElementTree returns None for the empty element (other XML libraries may do the same).
4. Requiring the constant metadata keywords: CelesTrak CSV/JSON omit CENTER_NAME, REF_FRAME, TIME_SYSTEM, MEAN_ELEMENT_THEORY and the whole header.
5. One epoch format: CCSDS allows day-of-year, no fraction and a trailing Z.
6. Assuming CLASSIFICATION_TYPE is U, that ELEMENT_SET_NO is never 0, or that a CSV has no columns you do not know (RMS, DATA_SOURCE in supplemental data).
7. Comparing a TLE to its OMM digit for digit: the TLE truncates eccentricity to 7 digits and rounds the BSTAR and second-derivative mantissa to 5, so OMM to TLE to OMM does not round trip.
8. Reading MEAN_MOTION_DOT as the true derivative: the OMM carries the TLE field as printed (the ndot/2 convention).
9. Storing the catalog number as an Alpha-5 string internally: python-sgp4 cannot load any nine-digit record, and such records are live (launch nominals of the 18th Space Defense Squadron, 18 SDS, in CelesTrak SupGP).
10. Writing a TLE with the catalog number through an integer format (%05d, f"{n:05d}"): above 99999 that yields six digits, a 70-character line and a checksum over shifted columns. The field must be Alpha-5 from 100000, and a number above 339999 cannot be written as a TLE at all: the correct output is a refusal, and the record belongs in an OMM format.

What to change. Parse the catalog number as an integer from any source; decode Alpha-5 strictly (reject I, O, lowercase) if you read Space-Track TLEs; treat empty OBJECT_ID and OBJECT_NAME as legitimate; default the constant metadata; accept all CCSDS epoch forms; tolerate unknown keys and non-U classifications; compare TLE and OMM under the precision rules; treat a TLE 404 as "unrepresentable in this format", not as an outage; and prefer the OMM formats, which are what both providers say the future is. When writing TLEs, encode the catalog number as Alpha-5 above 99999 and refuse numbers above 339999 (or below 0).

What is in the corpus, and what is not

in the repository	not in the repository
fixtures/<case>/expected.json: frozen expected values and structural checks for 17 cases, all numbers as decimal strings	raw CelesTrak responses (fixtures/<case>/raw/): rebuilt on your machine by tools/fetch.py or gpconf fetch under CelesTrak's own usage policy
fixtures/<case>/case.md: what the case tests, how to read a failure, coverage gaps stated per case	Space-Track data, in any form (a .gitignore guard refuses such paths)
derived/: Alpha-5 TLE lines rendered from real CelesTrak OMM records (letters A and T only), six CCSDS-legal KVN variants, each with a provenance sidecar	invented element sets: none, anywhere
vectors/: specification vectors (Alpha-5 table, catalog-id text forms, two-digit-year pivot, CCSDS epoch strings)
manifest.json / MANIFEST.md: every source with URL, retrieval time, SHA-256, tier; every check and ambiguity by id	SupGP-derived snapshot values: the element values of CelesTrak supplemental records are withheld from the public release; those cases keep their structural checks and run against your own fetch
schemas/: SANA NDM/XML schema sets 2.0.0 and 4.0.0, unmodified
gpconf/: the runner (standard library, Python 3.9+) and the adapters and harnesses behind its presets
harnesses/: recipes for the five hand-run libraries that cannot be presets (libsgp4, Gpredict, SatDump, astroz, gods-eye-view): each harness, its pinned commit and build commands; best-effort, not in the pip package, and tied to the projects' internals (D-155)	SatDump's link stand-ins: the recipe lists the symbols to define instead (D-152)
docs/: the adapter guide (docs/ADAPTERS.md), research notes with verbatim sources, cross-check, breakage catalogue, upstream bug-report drafts; AUDIT.md: the independent audit and its resolutions

The pip package, gpconf, carries the runner and the corpus's own files: every case's expected.json and case.md, derived/, vectors/, manifest.json and the fetch list. It carries no provider data; the schemas, the other documents, the build tools, the test suite and the recipes stay in the repository.

Why no raw files: CelesTrak's site states no redistribution terms for its data (docs/RESEARCH.md §11), and silence is not permission. Rebuilding locally means the provider's terms apply to you directly, fixtures cannot rot unnoticed, and SHA-256 hashes tell you whether you are looking at the exact bytes we tested.

Quick start

From v0.3.0 the runner installs from PyPI with the corpus's own files; the provider data is fetched once, into a per-user cache:

pip install gpconf
gpconf run --preset reference   # before any fetch: the 4 cases whose files ship in the package run; 13 say they need provider data
gpconf fetch                    # once: ~60 requests, ~12.6 MB, 2 s apart, cached, never repeated
gpconf run --preset reference   # then all seventeen, as in a clone

Or from a clone, as before:

git clone https://github.com/hneogy/gp-omm-conformance.git && cd gp-omm-conformance
python3 tools/fetch.py            # once: ~60 requests, ~12.6 MB, 2 s apart, cached, never repeated
python3 -m gpconf run --preset reference   # the control: 16 cases pass; the SATCAT case is a data check reported not-exercised for every parser, and the nine-digit case says not-exercised outside a launch window
python3 -m gpconf run --preset naive       # the parser most projects have: a demonstration of failure, not a parser to use

Installed, the command is gpconf; in a clone it is python3 -m gpconf; the two take the same arguments. A preset runs a shipped adapter with nothing written. python3 -m gpconf presets lists them: reference and naive (standard library only), sgp4 (needs python-sgp4: pip install sgp4, or pip install "gpconf[sgp4]"), pyephem (needs PyEphem: pip install ephem, or pip install "gpconf[pyephem]"), and three that need Node.js and the library installed where you run the command: satellite.js, tle.js, which reads the epoch from the raw year and day fields, and tle.js-api, which reads it through getEpochTimestamp(). A library preset records the version it was tested against and the report prints the version it found beside it, since a count is a result against one version. A Node preset's harness runs from the working directory, so the library resolves as it would for a script in your project; --module PATH names the library's entry file instead, for a checkout that cannot import itself by name. A preset whose library is missing is refused before any case runs, with exit status 2 and a message saying that nothing ran and that this says nothing about the library (D-153, D-154). The adapters are in gpconf/adapters/; the older names tests.adapters.reference:Parser and the like still work (D-151).

In a GitHub Actions job, from v0.3.0, three lines run a preset against your library:

- uses: hneogy/gp-omm-conformance@v0.3.0
  with:
    preset: sgp4

Install your library first, in the job's Python (the python input names the interpreter) or, for a Node preset, in the job's working folder. The Action runs the corpus from this repository at the tag you name, so a corpus release changes nothing in your CI until you move the tag. It runs offline and fetches nothing: only the cases that ship with the corpus run, and the rest are reported as needing provider data. It is report-only: failed cases do not fail the job, and the job summary carries the case table, the gate line and the reminder that a count is a result against that version on that date, not a verdict on the project. A preset whose library will not import fails the job as a setup error, exit status 2, saying that nothing ran. There is no badge (D-153, D-158).

Then write an adapter for your own parser: a Python class the runner imports (--adapter module:Class), or, for a parser in any other language, a command that reads a file on standard input and prints JSON (--cmd, with --vectors-cmd and --write-cmd for the hooks). docs/ADAPTERS.md is the guide.

If the writer cannot be wrapped at all (an interactive program such as strf's rffit, which satno2tle drives), check the file it wrote instead. The format checks need nothing else; the round trip needs the source records the lines were written from:

python3 -m gpconf check-tle output.tle                          # lines, checksums, catalog field, column layout
python3 -m gpconf check-tle output.tle --against records.csv    # plus the round trip, per record

Name lines, # comment lines (rffit's trailer) and LF or CRLF endings are accepted; a six-digit number in the catalog columns is reported with the Alpha-5 form it should have had, and a number the format cannot carry with the statement that a refusal was the correct output. Exit code 1 on any failure or when no record is found.

python3 -m gpconf list prints the cases and their tags; --case ID and --tag TAG select.

Fetching responsibly

tools/fetch.py follows CelesTrak's published usage policy (https://celestrak.org/usage-policy.php): each URL once, files cached with metadata, no redirects followed, no retries, 2 s between requests, and it stops on the first unexpected response. The largest file is the 9.4 MB legacy SATCAT; leave it out with --skip-case satcat-70000-cutoff if you do not need the 70000-cutoff case. Do not run the fetch more than once per two hours; the tool never re-fetches a file it already has (with or without its metadata) unless you pass --force and the recorded retrieved_at is at least two hours old, and it never requests a URL twice in one run (a re-capture entry is requested only when its original is on disk and two hours old). After each run it compares every file with the SHA-256 recorded in manifest.json, prints a DRIFT line for any stable-tier source whose bytes differ and exits 2 (--check-drift does the comparison without fetching). If you receive an HTTP 403 read the body: CelesTrak explains why.

The same fetch runs as python3 -m gpconf fetch, with the same options. In a clone it writes the provider files under fixtures/<case>/raw/ as always. --data DIR, or the GPCONF_DATA environment variable, puts them in another folder, and gpconf run then reads them from the same place. A copy of the runner outside a clone reads its corpus from the package and keeps the provider files in a per-user cache folder, one per corpus version: ~/.cache/gpconf/<version> (or under $XDG_CACHE_HOME) on Linux, ~/Library/Caches/gpconf/<version> on macOS, %LOCALAPPDATA%\gpconf\Cache\<version> on Windows. The run prints that folder above the case table whenever it is not the corpus's own (D-150). When a new corpus version's folder is filled, a stable-tier file whose bytes hash to the new version's recorded SHA-256 is copied from an earlier version's folder, with its metadata, instead of requested again; the fetch prints reused from <version> for it, its metadata records reused_from, and the run report says how many files were reused. Live files are always requested (D-157).

Two tiers: snapshot and live

Each source in the manifest is stable or live.

• stable (CelesTrak gp-first.php first-ever records, derived files, vectors): if your fetched bytes hash to the recorded SHA-256, the frozen, human-verified expected values are applied exactly.
• live (rolling groups, current objects, supplemental data, SATCAT records): CelesTrak updates every two hours, so your bytes will differ from the tested snapshot. The runner then applies the case's structural checks (cross-format agreement, count relations, presence rules, 404 semantics) and compares values against the corpus's own reference reader applied to your bytes, and it says so in the report. The snapshot values remain in expected.json as a dated reference.
• mixed (the pairs, facts and XML-schema cases, which list files fetched for other cases): the case uses the file structurally and applies no frozen values of its own; whether the file may drift is judged by the tier the fetching case records (D-114). Vector and derived files ship with the repository and are never fetched; their source rows say so instead of an HTTP status.

Writing an adapter

An adapter hands the corpus's files to your parser and returns what it read, in the corpus's field names: a Python class with a parse(raw, fmt) method, or a command that reads a file on standard input and prints a JSON array. Optional hooks answer the vector case and the writer case, and a refusal channel reports a record the library rejected, with the library's reason. docs/ADAPTERS.md is the guide: both protocols, the refusal channel, how returned records are counted, the hooks, running and reading a report, and what an adapter must not do, with worked examples copied from the shipped adapters. The sections below describe how any parser's results are judged and reported.

Tolerances, and how they are reported

The oracle values are exact decimal strings. For the parser under test the runner allows:

comparison	tolerance	why
a value you return as a binary float	1e-12 relative: abs(got − want) / max(abs(got), abs(want)); an exact zero on either side must be matched by an exact zero	most decimal element values have no exact double; 1e-12 is far below any physical meaning and above the noise of unit conversions (observed 1e-16 in docs/CROSSCHECK.md)
an epoch you return	2 microseconds	python-sgp4's Julian-date epoch differed from the exact value by up to 1 microsecond in the cross-check (docs/CROSSCHECK.md)
TLE epoch against the OMM epoch of the same record	432 microseconds	half of the TLE's 1e-8 day resolution; the provider itself rounds here

Everything else is exact. A check that passed only because of a tolerance is reported as pass-tolerance, separately from pass (exact), with the per-field count, mean signed difference and maximum, so a systematic sub-tolerance bias is visible instead of hidden. The reference adapter must be exact; the test suite enforces that.

A provider file that is not on disk is reported as not-fetched, never as skip: the corpus does not ship provider data (see "Fetching responsibly"), and skip is kept for a parser that has no reader for a format or no hook for a check. A case with none of its provider files reports not-fetched; the count line says how many cases need fetched data, the n/f column counts the missing files per case, and the runner prints the command that fetches them. A case that ran on some of its files keeps the result of those files and is named below the count line. The three re-capture files are an example: each is the same endpoint requested a second time when the corpus was built, and the fetch requests it only with --include-recaptures, so a normal fetch leaves those three cases without it (D-150 corrects D-148's wording here, which said a later run would bring it). A file that ships with the corpus (under derived/ or vectors/) and is missing stops the run with exit status 2, since the copy is incomplete and no status would be true of the parser (D-148).

A source file the corpus's own reader reads zero records from, where the manifest records some, fails the case with a source-readable item that says what the file looked like (size, first bytes, and a guess such as an HTML error page, an empty file, a BOM prefix or a TLE cut off after line 1), and the file's other checks are not run; a 16-byte CelesTrak 404 body is a legitimate zero-record file and stays empty-404. A stable-tier source whose bytes no longer hash to the recorded SHA-256 is reported, not silently treated as live: the case gets a failing stable-source-drift item naming the recorded and actual hashes, the JSON report gets a drift field, and the file's values item says the frozen expected values were not applied and that the parser was compared against the reference reader instead.

The provider's empty answer

Four cases hold a recorded answer with no data in it: CelesTrak's HTTP 404 body, No GP data found or No SupGP data found, for a group with nothing in that format. The runner hands that body to the parser under test (check empty-answer-yields-no-records): zero records and no error is the pass, an exception or an invented record is a failure, and a parser without the format skips. The point is the distinction: an empty but valid answer is one of three outcomes a parser must keep apart from "this file is unreadable" and "this value cannot be represented", and an error here collapses the first into the second.

The gate: this month's launches

Below the case table the runner prints one gate, a headline read across existing cases rather than a new case: given the objects launched in the last 30 days, as a provider serves them, does the parser return them with the right identity? Its inputs are the CelesTrak CSV capture of the last-30-days group (256 objects, every one above 99999, captured 2026-09-21) and the corpus's Alpha-5 rendering of the same records, the form Space-Track's TLE output carries. Per format the parser reads, records are counted as loaded (returned with the expected integer id), misidentified (returned as 0, NaN, a string or a wrong number) or dropped (no record came back). The wording names the behaviour and never grades the project: "reads this month's launches", "only via CSV", "not in any format it reads", and, for a parser that reads TLE only, "nothing to load from this feed", because CelesTrak's TLE output omits these objects. A format that was never tried, because its file was not fetched or its case was not selected, limits the claim: the headline then says "every format measured here" or "not in any format measured here", names the format left out before the numbers, and never says "nothing to load from this feed", which would claim the parser reads TLE only. A freshly fetched CSV holds different records from the frozen capture; it is judged against its own record count and labelled as a live capture (D-148). Every headline carries the snapshot's date, count and id range, and the letters its Alpha-5 fields begin with: a decoder that is wrong from J upward passes a snapshot whose ids all begin with A. The JSON report carries the same under gates, with the counts, and each values item now carries its record counts under counts.

The seventeen cases

case	what it covers
epoch-year-19xx	first ISS record (1998) in seven renderings; two-digit year 98; negative first derivative; non-zero second derivative
baseline-iss-five-formats	a current object in every rendering (live)
six-digit-omm-saramago	catalog number 100000, stable and live; TLE request 404
tle-omits-six-digit-objects	a group that is entirely six-digit: 256 OMM records, TLE request 404
analyst-objects	empty OBJECT_ID, UNKNOWN names, 8xxxx and 27xxxx ids, TLE keeps only the five-digit ones
nine-digit-supgp-launch-nominals	nine-digit ids (7995016xx) in CelesTrak supplemental data; perishable
supgp-celestrak-classification-c	classification C, element set 0, extra columns, 72000-series ids
bstar-and-derivative-forms	negative BSTAR and first derivative, non-zero second derivative, implied-decimal fields
satcat-70000-cutoff	legacy SATCAT stops at 69999; CSV/JSON SATCAT continues
csv-json-omitted-mandatory-fields	CelesTrak CSV/JSON omit the constant CCSDS-mandatory keywords
mean-motion-derivative-convention	OMM MEAN_MOTION_DOT equals the TLE field as printed (304/304)
tle-vs-omm-precision-loss	eccentricity truncated, mantissa rounded half up, SupGP epochs quantised; TLE→OMM→TLE round trip tested (the 24-character name limit is a format rule, not observed in provider data)
omm-xml-schema	valid NDM/XML 2.0, invalid against 3.0 on the version attribute alone
alpha5-encoding-vectors	the Space-Track table, official examples, boundaries, invalid inputs
alpha5-tle-derived	604 derived Alpha-5 lines (letters A and T) from real CelesTrak records
kvn-syntax-variants	six CCSDS-legal KVN renderings CelesTrak never emits
tle-writer-alpha5	writer side: 606 frozen records (603 Alpha-5 ids, three five-digit) written through write_tle, plus three numbers the TLE field cannot carry, for which a refusal is the correct output

Full detail, sources and per-case gaps: MANIFEST.md; per case: fixtures/<case>/case.md.

Known gaps (summary; each is also stated in the case that has it)

• Real catalog numbers exist only for Alpha-5 letters A (100000-100789) and T (270000-270449, Space Fence analyst objects). Other letters are covered by vectors only.
• The renderer behind the derived Alpha-5 lines was validated (304 of 304 lines byte for byte) only against sub-100000 CelesTrak output, because CelesTrak emits no Alpha-5. The encoding step is corroborated by python-sgp4's independent implementation, by the official vectors, and by the maintainer's run of tools/verify_against_spacetrack.py against their own Space-Track account (44 records, zero defects, letters A and T; D-070). The derived lines remain CelesTrak-style renderings: Space-Track's own TLE lines for the same records differ in the sign written for a zero second derivative and in the last eccentricity digits, so they are not byte-identical to Space-Track output. The rendering rule the corpus applies (eccentricity truncated, BSTAR and second-derivative mantissa rounded half up) is CelesTrak's, derived empirically from those 304 records and documented in no specification we located.
• No positive-exponent BSTAR (>= 1.0) exists in the fetched data. One synthetic-derived writer input (id 99999, BSTAR 1.2345, TLE field 12345+1, rendered by the corpus, D-125) covers the field's form on the writer side only.
• Nine-digit ids exist only in supplemental launch nominals for roughly a week after a launch; outside that window the case reports not-exercised. What happens to a nominal's identity after that week is an open question the corpus states and does not answer: it checks that the nine-digit and six-digit forms both parse, holds no object in both, and has no ground truth for how a tracker should correlate a nominal with the catalogued object that follows it; the shared launch designator is not one-to-one. The nine-digit case's gaps say why that is out of scope rather than missing.
• Stability of CelesTrak's gp-first.php over time is assumed, not yet observed; tools/fetch.py compares every fetched file with the manifest after each run and reports DRIFT for stable sources whose bytes changed.
• The writer case's inputs are the corpus's own frozen records; no output of an external tool is shipped. strf's rffit (the writer behind satno2tle) was exercised at function level only, in a scratch build outside the repository, and has no adapter because it is an interactive X11 program (DECISIONS.md D-097).

Library behaviour found while building the corpus

Documented in docs/CROSSCHECK.md, with draft upstream reports in docs/upstream/:

• python-sgp4 2.27 and Skyfield 1.55 raise ValueError for every nine-digit NORAD_CAT_ID loaded from OMM data.
• python-sgp4's sgp4.omm.parse_xml turns an empty <OBJECT_ID/> into None and initialize() raises TypeError on 564 of the 566 analyst XML records in the case (563 of the 565 group records, plus the single 270449 first record).
• python-sgp4's export_tle writes a zero second derivative as 00000-0, which matches Space-Track's rendering; CelesTrak writes 00000+0, so byte-exact round trips of CelesTrak lines fail while values agree. A provider divergence, not a library defect; documented in docs/upstream/, not filed (D-072).
• python-sgp4's omm.initialize sets the classification and then sgp4init resets it to U, so CelesTrak supplemental records (C) come back as U; and its Alpha-5 decoder accepts I, O, lowercase and four-character input that Space-Track's definition excludes.
• As a writer, python-sgp4's export_tle encodes Alpha-5 correctly and omm.initialize refuses 340000 and nine-digit numbers, the correct output for a TLE writer; to_alpha5(-1) still yields -0001, so a negative number is written rather than refused.

Writer-side tools

The writer case (tle-writer-alpha5) and check-tle exist because every newly catalogued object needs an Alpha-5 field and amateur tools generate TLEs for new launches. Three writers were run (docs/FAILURES.md): the corpus's own renderer passes every check; a writer that formats the catalog number as an integer fails every Alpha-5 input; python-sgp4 2.27's export_tle passes every real record and refuses 340000 and nine-digit numbers, failing only the synthetic -1 vector.

strf's rffit, the writer behind satno2tle, could not be built here and is interactive, so it has no adapter; its two formatting functions were exercised unmodified in an isolated build outside the repository. Tested at function level: correct Alpha-5 across the representable range and valid lines for real records; above 339999 no range check, so the lines carry a blank catalog field, on a route only the interactive Satellite ID entry takes and that no real catalog number reaches today. Labels, details and the reproduction recipe are in docs/WRITERS.md. No bug is claimed for the binary; a short hardening suggestion, docs/upstream/strf-number-to-alpha5-range-check.md, was filed as cbassa/strf#88 on 2026-09-23. Users of rffit or satno2tle can check the file it wrote with python3 -m gpconf check-tle.

Upstream

Status of the findings above with python-sgp4, as of 2026-09-24:

• Empty <OBJECT_ID/> import failure: filed by the maintainer of this corpus as brandon-rhodes/python-sgp4#171 (draft and prepared patch in docs/upstream/); the patch, PR #172, opened 2026-09-21 and amended 2026-09-23 after the maintainer's review, was merged by the maintainer on 2026-09-24 as commit 8126f77, and #171 is closed. No release carries the fix yet (the latest is 2.27 of 2026-07-03), so the python-sgp4 results in this README and in docs/FAILURES.md, 7 of 17 cases, are against 2.27 and stand until one does.
• Nine-digit NORAD_CAT_ID rejected: independently reported before this corpus existed as #169, with PR #170 open. Not filed again. PR #170 at head 5e4f308 was tested locally against the sixteen cases the corpus had at the time, on both the accelerated and the pure-Python build: it adds two tests and no library code change, the nine-digit reproducer still raises, and the runner results are identical to the 2.27 baseline (0 fixed, 0 regressions). The test report is in docs/upstream/pr170-test-comment.md (DECISIONS D-088).
• export_tle zero second derivative ( 00000-0): not a library defect, not filed (D-072).
• omm.initialize classification reset to U: draft note only, not filed.

For strf, docs/upstream/strf-number-to-alpha5-range-check.md holds a hardening suggestion, not a bug report, drafted 2026-09-22 (D-101) and filed as cbassa/strf#88 on 2026-09-23 (D-108).

Verifying the derived Alpha-5 lines against Space-Track yourself

CelesTrak emits no Alpha-5 TLEs, so the corpus's Alpha-5 lines are rendered from CelesTrak OMM records (derived/alpha5-tle/). Space-Track does emit Alpha-5 for catalog numbers 100000–339999. The corpus redistributes no Space-Track data, and its Space-Track name guard keeps any such data out of the repository; but anyone with their own Space-Track account can check the encoding against provider output:

python3 tools/verify_against_spacetrack.py

The tool asks for your Space-Track username and password interactively (never as arguments, never logged or stored), logs in, runs exactly four queries at least three seconds apart (the current records for 100000–100020 and 270000–270020, and the first historical record of 100000 and of 270449), logs out, saves the raw responses under ~/spacetrack-verify/ (it refuses to run if that directory would be inside the repository), and compares each returned TLE with the derived lines. It prints only catalog fields, verdicts, differing column numbers and summary counts, never element values or lines. In the maintainer's run (2026-09-21, D-070) no line was byte-identical and none was expected to be: Space-Track writes a zero second derivative as 00000-0 (column 51, and the checksum at 69) where CelesTrak writes 00000+0, and its eccentricity field differs in the last one or two digits (columns 32–33) from CelesTrak's truncated rendering on exactly the 8 of 21 same-epoch records where rounding and truncation disagree (D-071); what the run verified is that every Alpha-5 field decoded to the queried id, every line-2 field matched line 1, and designators and inclinations agreed. Use of Space-Track is governed by its user agreement; keep the saved responses to yourself.

Reproducing or refreshing the corpus

The build is a pipeline of small scripts, all in tools/, all offline except fetch.py: fetch.py → inventory.py → validate_render.py → derive_alpha5.py, derive_kvn_variants.py → make_expected.py → crosscheck.py (needs python-sgp4, Skyfield and xmlschema, pinned in tools/crosscheck-requirements.lock.txt: pip install -r it into the environment you build in) → validate_xml.py → make_manifest.py → make_failures.py. Refreshing live sources produces new snapshot values and bumps the corpus minor version; frozen values of a released version are never rewritten.

Versioning

corpus_version in manifest.json. Patch: documentation and tooling only. Minor: refreshed live snapshots, added cases, or an additive protocol change. Major: changed expected.json schema or check semantics. Expected values published under a version are frozen; corrections arrive as new versions with a DECISIONS.md entry. The gpconf package carries the version of the corpus it ships, and the runner prints both on its first line.

How this corpus was built

The work ran in phases, each ending in a review by the project owner before the next began, under a written decision policy (CLAUDE.md) that required every non-trivial choice, reversal and correction to be recorded.

• Audit trail: DECISIONS.md is the complete, append-only log of decisions, including the ones that were reversed. Read it first if you want to know why something is the way it is.
• Sources: docs/RESEARCH.md records every document consulted, with verbatim quotations, URLs and retrieval dates.
• Data provenance: no element set was invented. Every value traces to a CelesTrak response whose URL, retrieval time and SHA-256 are recorded in the manifest, to a published standard cited by clause, or to a committed, labelled transformation of such a record (derived/, each with a .provenance.json).
• Verification: the expected values were produced by reference readers written from the format documents and cross-checked, record by record, against python-sgp4 and Skyfield (docs/CROSSCHECK.md); the renderer used for derived TLE lines was validated by reproducing 304 of 304 CelesTrak TLE lines byte for byte. Where a specification and the provider's practice disagree, both are recorded (manifest.json → ambiguities) and neither is silently chosen.
• Independent audit: completed on 2026-09-21, before publication; the report is AUDIT.md. It was performed by a separate AI session that had no access to the building session's context, was instructed to trust no document in the repository and to recompute values independently; it was not a human review. It found no wrong expected value and a number of documentation and tooling defects; every finding's resolution is recorded at the end of AUDIT.md and in DECISIONS.md (D-054 onward). The public copy of AUDIT.md withholds one row of its appendix table (a sample entry from the SupGP case, per D-033/D-049) and says so in a notice; the auditor's text is otherwise unchanged and the private original is intact. It covered v0.1.0; neither the writer-side case of v0.2.0, the fixes of v0.2.1 nor the packaging and protocol changes of v0.3.0 have been separately audited.

If you find an error, the most useful report names the case id, the source file's SHA-256 and the field, so that the discrepancy can be traced to a specific fetched byte sequence.

Licence and attribution

MIT, copyright NEOGY LLC (see LICENSE), for the corpus's code, documentation, vectors, derived files and expected values. Provider data is not included; tools/fetch.py retrieves it under CelesTrak's own terms. The schemas under schemas/ are CCSDS/SANA publications redistributed unmodified.

Data source: CelesTrak (Dr. T.S. Kelso), https://celestrak.org, a 501(c)(3) non-profit that makes this data freely available; please respect its usage policy. Standards: CCSDS 502.0-B-3 (Orbit Data Messages) and CCSDS 505.0-B-3 (XML Specification for Navigation Data Messages). Alpha-5 definition: Space-Track, https://www.space-track.org/documentation.

To cite, use CITATION.cff (GitHub's "Cite this repository" reads it): Neogy, H. (NEOGY LLC). gp-omm-conformance, version 0.3.0, 2026-09-27, https://github.com/hneogy/gp-omm-conformance. Two Zenodo DOIs exist: the concept DOI 10.5281/zenodo.22867654 refers to the corpus as a whole and always resolves to the latest release; use it when you mean the corpus in general. The version DOI for this release, v0.3.0, is added here and to CITATION.cff after Zenodo mints it at the release; v0.2.1 keeps its own, 10.5281/zenodo.22926017, v0.2.0 its own, 10.5281/zenodo.22906966, and v0.1.0, the release the independent audit covered, keeps 10.5281/zenodo.22867655. Use a version DOI when your results depend on a specific set of expected values; each release gets its own under the same concept DOI.