Re: Mir and the good old days

From: Jonathan T Wojack (tlj18@juno.com)
Date: Tue Jun 26 2001 - 14:36:12 PDT

  • Next message: Randy John: "RE: Mir and the good old days"

    > So, what do you do with elements when you don't have a computer?  
    > You use a
    > 3 inch diameter globe (filled with pennies) and a piece of string of 
    > course.
    > The first thing that you do is hope that the eccentricity is close 
    > enough to
    > zero so that you can ignore it.  The only two numbers that are 
    > really
    > important are the inclination and the period.  Using a known pass, 
    > you lay
    > the string on the globe so that it passes through your site and has 
    > max/min
    > latitude the same as the inclination.  Now you can make future 
    > predictions
    > since you know where Mir will be in 15, 16, 30, 31, 46 or 47 orbits 
    > from
    > now.  During these passes the Earth will have rotated approximately 
    > 1, 2 or
    > 3 revolutions.  Of course, you had to make up for the difference 
    > between
    > "approximately 1 rev" and the actual amount of time.
    
    Using TLE data, I using a known H-A prediction for my site for SeaSat 1. 
    I used the data to project when the satellite would be visible 9 days
    later.  My prediction was only 4 minutes off the H-A prediction (which
    are almost always +/- 10 seconds that far into the future) !!!  So this
    works!  Thanks a lot for sharing this with us.
     
    > Using this method I successfully predicted a pass at my dark sky 
    > site more
    > than 150 miles away from the prediction city.  If you don't believe 
    > me, I
    > have a picture with Mir's trail about 5 degrees above the horizon to 
    > prove
    > it (I didn't actually see it).
    
    Randy, if you're listening, can you explain how to factor the inclination
    of the satellite into the calculations.  I don't see why it matters (for
    the sake of calculation) .  Also, is there a way to estimate the altitude
    of the satellite when observed (I understand how to determine in what
    area of the sky the satellite will "peak" in).
    
    Thanks very much!
    
    ------------------------------
    Jonathan T. Wojack                 tlj18@juno.com
    39.706d N   75.683d W           
    
    4 hours behind UT (-4)
    
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