[MOIMS-NAV-EXEC] OMM-KVN from space-track.org

[Lamy Alain]

Hi,

Thanks for these elements about the context.
The TLEs were obtained using the API (beginning of April, I think).

In case that was not clear, the purpose of the email was not to reproach anything to space-track.
It was to foster discussion inside the working group on aspects such as:
- The syntax of a comment line : is it described clearly enough in the standard ?
- Grouping several KVN messages into one single file : wouldn’t  it be a good idea to have that possibility for all CCSDS (navigation) standards ?

About JSON, this is not (at the moment at least) a format used for CCSDS navigation messages.
But having JSON as a possible format for TLEs is probably appreciated by some users, so that’s fine !

Best regards,

Alain Lamy

From: Robert Wolff - NOAA Federal <robert.wolff at noaa.gov>
Sent: jeudi 12 juin 2025 22:01
To: Lamy Alain <Alain.Lamy at cnes.fr>
Cc: moims-nav-exec at mailman.ccsds.org
Subject: Re: [MOIMS-NAV-EXEC] OMM-KVN from space-track.org

Hi,

I've used space-track quite a bit and have worked with their developers, so I may have useful additional context.

First, I can't figure out how you got those TLES/OMMs. It looks nearly identical to the response you would receive from their GP class API endpoint, but that endpoint doesn't seem to support KVN anymore. Maybe they've deprecated the KVN format since January when those were produced. Their API documentation does say they've been working on deprecating some of their OMM formats. If it would be helpful, I could ask if they did that.

Second, I think space-track knows that the equal signs are not required, but pretty much any space-track KVN product I've seen has equal signs in the comments. I believe it is so anyone who builds parsers specifically for space-track instead of for the OMM in general can build parsers that split each line at the equal sign.

Presumably you retrieved these through the space-track API, right? Space-track doesn't keep OMMs inside a file structure. They instead use a relational database. So when requesting multiple of any of their data products through their API, it will return all of them to you in the same response.

It's also probably worth mentioning that JSON OMM's do not follow CCSDS standards in that they remove the USER_DEFINED_ tag off the user defined fields. They also actually have the true TLE lines contained in the non-CCSDS compliant versions (HTML, CSV, JSON), but not in the CCSDS compliant versions (XML, KVN?). I think it would be fair to say the space-track, and the past version do not believe that CCSDS standards apply to JSON formats.



On Wed, Jun 11, 2025 at 9:54 AM Lamy Alain via MOIMS-NAV-EXEC <moims-nav-exec at mailman.ccsds.org<mailto:moims-nav-exec at mailman.ccsds.org>> wrote:
Hi everyone,

I recently got TLEs from the spacetrack.org<http://spacetrack.org> website.
Many formats are available, including classical TLEs, JSON, OMM-XML, OMM-KVN.
Attached is the KVN version (SWOT S/C).
There are 2 (possibly) interesting points :

-        The “COMMENT” lines are written : COMMENT = xxx

It may means that the description is not precise enough ?

-        As they wanted to minimize the number of files (I suppose), all KVNs are grouped in one single file.

Not strictly compliant but convenient.

Alain

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