Re: STS-116 & ISS 600 feet sep. for SE United states

Date: Tue Dec 19 2006 - 00:57:09 EST

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    In a message dated 12/18/06 9:22:51 PM Eastern Standard Time, writes:
    << It's my great hope that chicago will have clear conditions to the SE.  
     visible passes during docking or undocking/ approach/ sep procedures sure 
     seem rare, I saw my last in 1999 or 2000! a question I have for some of the 
     veterans:  at these ranges (>547 km and 200m), will I be able to distinugish 
     the 2 separate objects? my gut tells me yes. >>
    I was wondering the same question, except I live in the Greater New York 
    Area.  On Tuesday, the Shuttle/ISS tandem is predicted come closest to us at 6:03 
    p.m. EST, at a range distance of 499 kilometers or 310.02 statute miles.  
    So . . . if the distance/gap between the Shuttle and the ISS is 600-feet and 
    is viewed from a distance of 310.02 miles, what is the angular separation 
    between the two vehicles.  To solve this problem, we would use the equation
    57.3 x G
    Where G = the gap between the two vehicles and D = the distance of the two 
    vehicles from the observer.  But first, we must either change the size of the 
    gap to miles. or the distance to feet.  In this case, it seems easier to change 
    miles to feet. Since 1 statute mile = 5,280 feet, 310.02 miles = 1,636,952 
    feet.  Now we can write: 
                                                        57.3 x 600
    Separation in angular degrees =    ___________   = 0.021 degrees
    So the Shuttle and ISS should be separated by only 1.26 arc minutes
    or 75.6 arc seconds.  I strongly suspect that this very small separation
    will make both objects appear as one to the unaided eye for most
    people (I "think" that for the average person, 3-arc minutes would be 
    about the limit of visual perception; 7X binoculars on the other hand 
    should quickly reveal that there are indeed two objects flying by.
    -- joe rao 
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