KMS-4 orbit: JSpOC versus DPRK claims

From: Marco Langbroek via Seesat-l <>
Date: Sun, 7 Feb 2016 19:11:50 +0100
Hi all,

I noted that the orbital parameters given in this DPRK announcement here:

...namely perigee 494.6 km, apogee 500 km, inclination 97.4 deg

is inconsistent with what we so far have from US tracking of the object. The
first few sets of orbital elements published by JSpOC on Space-Track give
(calculated from eccentricity and Mean Motion values) these values:

- perigee 465 km, apogee 502 km, inclination 97.5 deg

There is a clear difference in the apogee altitude here: 465 km according to
JSpOC, 494.6 km according to the DPRK.

Now, this could be due to initial inaccuracies in the JSpOC tracking data. The
first few elsets always have some variation and are less accurate usually.

Yet given the magnitude of the difference, I doubt this a bit.

Instead, and assuming that the values in the DPRK announcement are not based on
actual North Korean tracking but represent a pre-launch desired orbit, I wonder
if this is perhaps an indication that the satellite ended up in an orbit with
lower perigee than intended?

- Marco

Dr Marco Langbroek  -  SatTrackCam Leiden, the Netherlands.

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Twitter: _at_Marco_Langbroek
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Received on Sun Feb 07 2016 - 12:12:08 UTC

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