Re: Updated elements

From: Greg Roberts (grr@telkomsa.net)
Date: Thu Jun 10 2010 - 21:42:16 UTC

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    Hi Ted,
    
    Yes I agree with the mean motion you took for VORTEX 6 - my estimate was 
    about 1.00248.  I got the idea from the new feature in HEAVENSAT  ( Orbital 
    Evolution) to plot all the orbital parameters against date  going back to 
    since we first started observing it and the trend in orbital behaviour for 
    all the orbital parameters is very obvious.
    
    I want to try it on some other satellites that make changes to see if there 
    are any more patterns. I dont actually use the HEAVENSAT Orbital Evolution 
    option - Alex (the author) said there is an error which he is still working 
    on, but I instead used GNUPLOT - an excellant freeware plotting program.
    
    Basically you can have as many columns of data as you like in an ascii file 
    and with commands similar to "plot column 1 against column 11" for example 
    one can get a nice plot all automatically scaled - very useful for any 
    plotting of data. Its a very powerful program and there are numerous 
    options - also available, if memory correct, for LINUX and the MAC.
    
    For those who want to play with GNUPLOT this is a typical command sequence 
    ( works in DOS as well as Windows).
    
    set grid
    set xrange [3950:5400]
    set xlabel 'JULIAN DATE - 2450000'
    set ylabel 'MEAN MOTION - revs/day'
    plot '19976.txt' using 1:7
    
    set grid will plot a grid background
    xrange = range of parameter which in this case is Julian Date
    xlabel or ylabel  - should be obvious
    and 19976.txt is the ascii file of elements - about 25 sets for VORTEX 6
    using 1:7 means plot column 1 against 7 where column 1 is JULIAN DATE of 
    epoch and 7 is MEAN MOTION
    
    Of course the epoch for elements is not JULIAN DATE so I had to write a 
    short program to convert the epoch to Julian Date.
    
    The commands are case sensitive. Obviously you also can set the yrange, 
    colors,symbols and more than one plot on the same graph- plus all sorts of 
    other things like 3D plots etc which I havent had time to explore yet.
    
    Read the MANUAL :-))
    
    Im sure some users will find this program very useful for all sorts of 
    plots.
    
    Cheers
    Greg
    
    
    
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