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Re: Suit-Sat still alive



David Barber wrote:

>Joe wrote:
>
>-----Original Message-----
>From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org] On Behalf
>Of jmario
>Sent: 06 February 2006 10:16
>To: amsat-bb@AMSAT.Org
>Subject: [amsat-bb] Suit-Sat still alive
>
>  
>
>>If its any consolation SuitSat and the ISS seem to be about 4 minutes 
>>apart...
>>    
>>
>
>
>
>I had keps (source celestrak amateur.txt) early yesterday that indicated
>this was the case yet those downloaded last evening and again today put the
>two only 30 - 40 seconds apart which seems to tie in with my reception at
>08.30UTC today.
>
>Can anyone give a definitive answer on what's going on here please?
>
>David
>G8OQW
>
>
>
>  
>


Hmmm

TLEs I had been using were relatively recent (2 days old I believe).

ISS
1 25544U 98067A   06 37.01390046  .00014187  00000-0  99238-4 0  2932
2 25544  51.6437 142.0732 0008873 241.1655 100.6034 15.74529506412484
SUITSAT
1 28933U 05035C   06 35.74763279  .01340357  00000-0  79197-2 0    20
2 28933 051.6359 148.5949 0008408 238.1112 122.0255 15.74821950   126


Assuming my observations were symmetrical about tca, the observed 
SuitSat tca
was about 3 minutes later than the predicted SuitSat tca.  I figured 
that was
close enough agreement...
Predicted tca: 14:34:34    Observed tca:  14:37:55


Your comment set me to looking closer and checking Celestrak for new TLEs.


Picked up fresh TLEs from Celestrack at 15:30Z today Feb 6, 2006.


ISS
1 25544U 98067A   06 37.34746006  .00013796  00000-0  96596-4 0  2950
2 25544  51.6436 140.3586 0008850 242.1654 191.5919 15.74536977412544
SUITSAT                
1 28933U 05035C   06 37.14366817  .00029099  00000-0  19600-3 0    56
2 28933  51.6428 141.4056 0008451 244.7122 115.3093 15.74845401   342

Recalculating using these TLEs shows the interval between ISS and 
SuitSat is
about 40 seconds (as opposed to the 4 minutes predicted by the 2 day old 
TLEs)
and,  for my most recent observation,  the observed tca is now a lot 
closer to
the predicted tca.
Predicted tca: 14:38:49Z    Observed tca:  14:37:55Z

Thanks for the nudge - I needed it.

Joe, K3FMA
----
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