Re: KMS-4 orbit: JSpOC versus DPRK claims

From: Jonathan McDowell via Seesat-l <seesat-l_at_satobs.org>
Date: Sun, 7 Feb 2016 16:04:07 -0500
I was thinking more the difference between WGS-84 and the spherical 6378 km
Earth that's
used in SpaceTrack.org which can easily be 20 km at least. But the apses
are near the equator
in this case, for the latest elset I get
465.1 x 501.9 km   mean els, geocentric spherical Earth
468.3 x 505.2 km   WGS84 heights at geocentric peri/apocenter
466 x 514 km         WGS84 actual max and min heights above ellipsoid
(which are not at the apses of the ellipse)
458 x 503  km         osculating els at 1310 UTC
But all of these are different from the DPRK's claimed 495 x 500. So I
agree this is either a prelaunch estimate,
or an overoptimistic calculation by the DPRK orbit tracking folks under
pressure to make the boss happy :-)

Jonathan




On 7 February 2016 at 14:57, wkitty42--- via Seesat-l <seesat-l_at_satobs.org>
wrote:

> On 02/07/2016 02:02 PM, Marco Langbroek via Seesat-l wrote:
>
>> Op 7-2-2016 om 19:52 schreef Jonathan McDowell:
>>
>>> .. or they are referring heights to a different ellipsoid
>>>
>>
>> Ellipsoids with a 30 km difference?
>>
>
> the difference between WGS72 and WGS84??
>
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Received on Sun Feb 07 2016 - 15:04:51 UTC

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