I'm looking for information on commonly used geocentric artificial satellite ephemeris file formats. I'm working on extending an analysis tool for earth orbiting satellites to add the ability to read an additional ephemeris format (OEM), and thought I might add other common formats while I have it opened up.

To expand a bit, an ephemeris is a representation of the trajectory of an object over a period of time. It typically consists of a list of times and state vectors spanning the period of interest, and may include various meta-data regarding units, coordinate frames, time systems, etc.

In contrast to element sets (such as a TLE, VCM, or classical elements, etc.), which require the use of a propagator, object positions represented by an ephemeris are typically interpolated. This can facilitate sharing of data where all users may not have access to the same propagation models, and allows the inclusion of non-Keplerian considerations such as maneuvers, specific decay models, etc.

What I have so far:

STK Satellite Tool Kit, Analytical Graphics

OEM (Orbital Ephemeris Message) CCSDS Recommended Standard

CALIPER JSPOC launch ephemeris format

JSPOC Ephemeris JSPOC on-orbit format

SP3 National Geodetic Survey - may be specific to GPS

SPK Ephemeris format associated with SPICE

CPF - Consolidated Prediction format, used by the ILRS

Code 500 - Source document appears to be GSFC Document "Flight Dynamics Division (FDD) Generic Data Products Formats Interface Control Document (document number 553-FDD-91/028" which I haven't been able to locate yet.

I'm sure I'm missing a lot of stuff here, but my google-fu isn't finding it. Of course, every organization seems to have their own internal formats — I'm more interested in what folks are using to publish or otherwise exchange data between organizations.

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    $\begingroup$ I've expanded it a bit. I'm sure there isn't a definitive answer - there seem to be as many ephemeris formats as there are individuals that work with satellites. But there are certainly some more common publicly defined formats. I think a list of those, and maybe information about what communities use them, would be useful. $\endgroup$ Commented Mar 1, 2016 at 1:17
  • $\begingroup$ Ok - I'm happy to delete it if it's inappropriate. I think it's a useful question and likely to be referenced by others - seems odd to dismiss it because determining who gets the credit for contributing may not work well. Gotta go - I'll see where things stand in the morning. $\endgroup$ Commented Mar 1, 2016 at 1:37
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    $\begingroup$ I think its a useful topic too. I can also see that of the "exceptions" you mentioned it is similar conceptually to space.stackexchange.com/questions/646/…. Whilst that example is a bit messy it seems better to provide it as a service to ourselves than to exclude it. Perhaps the question could be edited in such a way as to discourage the messiness - e.g. just identify the required features without long winded opinion. $\endgroup$
    – Puffin
    Commented Mar 1, 2016 at 13:03
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    $\begingroup$ I just noticed that the link for OEM PDF is not working. Try this or this? Or maybe these are not the newest? $\endgroup$
    – uhoh
    Commented Sep 20, 2017 at 15:22

1 Answer 1


The list in your question is a decent starting list, but there are more to add, and I'd go so far as to say they should be ranked by total usage. My list is:

  2. SP3 - Heavily used for GPS (NGA and IGS)
  3. SPK - Often for interplanetary/deep space, but a lot of use
  4. STK - Internal format for AGI, but widely used, and read by other tools
  5. JSpOC - JSpOC internal on-orbit format used for debris tracking
  6. FreeFlyer - Internal format for a.i. solutions, used at NASA JSC/GSFC
  7. Code 500 - NASA GFSC Binary format
  8. CPF - Consolidated Prediction format, used by the ILRS
  9. JSpOC CALIPER - JSpOC Launch format

There are lots of internal or proprietary formats used by various tools and centers (SOGS-MOGS, OASYS, etc), and pretty much every launch provider has their own ephemeris format for launch data.

  • $\begingroup$ I tried to add more links, but due to the fact that I'm new here, I didn't have the access to add more than two links. $\endgroup$ Commented Mar 2, 2016 at 15:47
  • $\begingroup$ You now have votes, so you can add more links. Welcome to Space Exploration. $\endgroup$
    – kim holder
    Commented Mar 2, 2016 at 16:34
  • $\begingroup$ Thanks for contributing - I found mentions of Code 500, but couldn't find any references on it in a brief search. Hope you can add some links soon. $\endgroup$ Commented Mar 2, 2016 at 17:11
  • $\begingroup$ Yeah, Code 500 has been around forever, and I thought there would be public access to the spec, but so far the best I've found is here, but it seems to only focus on the header. $\endgroup$ Commented Mar 4, 2016 at 15:54
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    $\begingroup$ @uhoh, thanks for letting me know. I updated the link $\endgroup$ Commented Sep 20, 2017 at 18:41

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