Re: Low orbit objects list?

From: John Burns (seesat@john.geek.nz)
Date: Tue Mar 31 2009 - 15:03:37 UTC

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    Back on about the 16th March I posted some questions about calculating  
    this from the two line elements - here is how to calculate it yourself.
    
    You'll need 3 values:
    e = eccentricity from the TLE
    n = radians per second (mean motion in the TLE is in orbits per day  
    and needs conversion)
    GM = Geocentric Gravitationsl Constant
    
    If we take the space station as an example, (figures from a few weeks  
    ago) show the eccentricity as 0.0009604 and the mean motion as  
    15.71470012
    
    n =  0.00114280524 (meanmotion * pi * 2 / secondsinaday)
    GM = 398600.4418
    
    SemimajorAxis = cuberoot(GM /  n ^ 2) = 6732.8 kilometres
    
    This is from the centre of the earth.  For eccentricities of 0  
    (circular orbits) it is also the Semi Minor Axis, otherwise you can  
    calculate the Semi Minor Axis with the formula found at http://en.wikipedia.org/wiki/Eccentricity_(mathematics)#Ellipses
    
    Depending on how accurate you want to be, there are many different  
    ways to calculate the radius of the earth, or simply use 6378.1 km as  
    a fairly good average.
    
    Note: I'm using the caret (^) as an exponent function.  n^2 = n * n
    
    John
    
    On 31 Mar 2009, at 15:37, Darwin Teague wrote:
    
    > I am trying to find objects in orbits below 400 km. I take photos of  
    > the ISS and could use practice tracking fast moving objects. The  
    > only place I have found to see the perigee and apogee figures is in  
    > my favorites page on Space-Track.
    > So far I have these:
    >
    > TITAN 3C TRANSTAGE DEB
    > 1 01882U
    >
    > ROSAT
    > 1 20638U
    >
    > TRMM
    > 1 25063U
    >
    > ISS (ZARYA)
    > 1 25544U
    >
    > PROGRESS-M 65
    > 1 33340U
    >
    > ISS DEB (TOOL BAG)
    > 1 33442U
    >
    > OMID
    > 1 33506U
    >
    > Is there a way for me to find more?
    >
    > Thanks.
    >
    >
    > My web pages
    > http://negligentdischarge.com
    > http://loadmastervideos.com
    > http://darwinsastroworld.com/
    >
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