Re: KMS-4 orbit: JSpOC versus DPRK claims

From: Brian Weeden via Seesat-l <seesat-l_at_satobs.org>
Date: Sun, 7 Feb 2016 13:25:29 -0500
Yes, that would be my guess - JSpOC has it right, and the DPRK either
published the "desired" orbit, or messed up the maths.



---------
Brian


On Sun, Feb 7, 2016 at 1:11 PM, Marco Langbroek via Seesat-l <
seesat-l_at_satobs.org> wrote:

>
>
> Hi all,
>
> I noted that the orbital parameters given in this DPRK announcement here:
>
>
> https://soundcloud.com/martyn-williams-6/voice-of-korea-on-kwangmyongsong-4-launch
>
> ...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.
> e-mail: sattrackcam_at_langbroek.org
>
> Station (b)log: http://sattrackcam.blogspot.com
> Twitter: _at_Marco_Langbroek
> PGP key: http://tinyurl.com/kur7xm8
> -----
>
>
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Received on Sun Feb 07 2016 - 12:26:28 UTC

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