Re: KMS-4 orbit: JSpOC versus DPRK claims

From: wkitty42--- via Seesat-l <>
Date: Mon, 8 Feb 2016 19:04:18 -0500
On 02/07/2016 04:04 PM, Jonathan McDowell wrote:
> I was thinking more the difference between WGS-84 and the spherical 6378 km
> Earth that's
> used in 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 :-)

i can agree with that... i admit that i didn't try to do the maths to see the 
actual differences... there's a lot of software out there that still uses the 
WGS72 values (eg: celestrak's published code)... i've asked some of them, in the 
past, if/when they were going to update to the WGS84 value and got no response 
OR something like "it isn't that critical so the report is marked as 'won't 
fix'" :?

if i had more knowledge of what numbers came from where, i would at least try to 
update the libraries i use in my software but :shrug:  i can see some 
similarities but quickly get lost in the details when trying to hunt down others :(

/me doesn't have as much of an eidetic memory as once upon a time when caffeine 
was the main source of energy... /me left the big city "rush rush rush, go go 
go, caffeine caffeine caffeine" life 20 years ago to return to the country 
life... that after doing 7 to 10 pots (yes 8-10 6-8oz cups) of coffee (European 
style) a day by myself for 20+ years... so glad to be off the hamster wheel and 
the addiction where i can enjoy life once more...

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Received on Mon Feb 08 2016 - 18:04:59 UTC

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