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I'm currently in the process of writing an SDK for the ESA's DISCOSweb API. I've come across these attributes on Orbital details.

"inc": 52.0,
"raan": 0.0,
"epoch": "1999-10-22",
"sma": 7791700.0,
"ecc": 0.00011,
"aPer": 0.0,
"mAno": null,
"frame": "J2000"

I can figure out what most of these are:

Abbreviation Long Form
inc Inclination
raan Right Ascension of Ascending Node
epoch Epoch/Time
sma Semi-major Axis
ecc Eccentricity
aPer Unknown
mAno Unknown
frame Frame

Does anyone know what the two unknown abbreviations refer to?

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    $\begingroup$ argument of periapsis and mean anomaly. Also "raan" is Right Ascension of the Ascending Node, sometimes also called longitude of the ascending node $\endgroup$
    – Alfonso Gonzalez
    Commented Dec 28, 2021 at 21:02
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    $\begingroup$ @AlfonsoGonzalez - Thanks bud, want to put that into an answer so I can accept it? $\endgroup$
    – ScottishTapWater
    Commented Dec 28, 2021 at 21:14
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    $\begingroup$ I'm curious: Do these numbers represent a real object, and if so, which object? It seems odd that mean anomaly at epoch is NULL $\endgroup$
    – notovny
    Commented Dec 28, 2021 at 21:18

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Argument of periapsis and mean anomaly. Also "raan" is Right Ascension of the Ascending Node, sometimes also called longitude of the ascending node

@notovny brings up a good point that its odd that mean anomaly is null, since eccentricity isn't zero so there isn't an ambiguity for AOP or true / mean anomaly.

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