Ofeq orbit-raising manoeuvre

From: Phillip Clark via Seesat-l <seesat-l_at_satobs.org>
Date: Sun, 13 Apr 2014 11:41:29 +0100
As a guide, starting with Ofeq 3, all of these satellites have performed a 
perigee-raising manoeuvre at their first pass through apogee.

Phillip Clark


----- Original Message ----- 
From: "Ted Molczan via Seesat-l" <seesat-l_at_satobs.org>
To: <seesat-l_at_satobs.org>
Sent: Sunday, April 13, 2014 8:23 AM
Subject: RE: BY C 041214


> Brad Young wrote:
>
>> If I get time, I'll double check star field of last point for OFEQ 10 Ted 
>> had to kick.
>> It would really help if all UNIDs would pass between bright, well known 
>> pairs and
>> asterisms in future. At least the fast retrograde motion made it obvious.
>
> Using the estimated TLE I posted Saturday, I found an asterism similar to 
> the one that you reduced to obtain your third
> point, but about 10 s further along-track. I am not certain of the 
> geometry you used in your reduction, but it appears
> to have been an appulse; applying approximately the same position angle 
> and angular miss-distance to what I believe was
> most likely the correct star, yields the third position below:
>
> 39650 14 019A   8336 F 20140412021354430 17 25 1334793+551697 48 S
> 39650 14 019A   8336 F 20140412021402340 17 25 1307069+620478 18 S
> 39650 14 019A   8336 G 20140412021441860 17 25 0619031+725444 48 S
>
> I weighted point #1 at 50 percent because the time seemed off by one 
> second or so. Allowing all but eccentricity,
> argument of perigee and rate of decay to vary yields:
>
> Ofeq 10                                                  383 X 620 km
> 1 39650U 14019A   14102.09307870  .00000000  00000-0  00000-0 0    03
> 2 39650 140.9339 218.7020 0172000  64.0412  16.4919 15.22366469    05
> Arc 20140412.09-0412.09 WRMS resid 0.377 totl 0.053 xtrk
>
> This should be accurate to within about 1 minute of time per 24 h from 
> epoch.
>
> You did well to spot it, especially given the inaccuracy of the TLE you 
> relied on, which was based on the wrong time of
> launch, and was obsoleted by the apparent subsequent manoeuvre to raise 
> the perigee.
>
> Ted Molczan
>
>
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Received on Sun Apr 13 2014 - 05:42:19 UTC

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