Re: ISS Magnitude, Atlas 5 Fairing

From: Michael McCants (mmccants@jump.net)
Date: Sun Jul 20 2003 - 21:23:21 EDT

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    Art Glick posted:
    
    >I was interested in seeing parts of the recent Atlas 5 that was 
    >launched.  It had an awfully large fairing around the upper stage.  I 
    
    Typically such fairings are discarded on the way up after the
    atmosphere gets thin enough.  It's a waste of good payload capability
    to put them in orbit.  The Japanese double payload launches are an
    exception.  The two fairings around the second payload are released
    after orbit is achieved.
    
    >I saw two items listed here (27852 & 27853), but alas, no passes at my 
    >location.
    
    Quicksat cannot be used for these objects due to the particular
    algorithm that it uses to find the culmination point for each pass.
    
    I have a different program called HighFly that uses an entirely different
    algorithm for generating predictions for such high objects.
    
    A typical prediction looks like this:
    
      ***  2003 Jly 28/29   Mon evening/Tue morning  *** Times are CDT ***
    
    27853 CENTAUR R/B                 M 2.5 ELDY 11 M2   -2
      U  MAG    HGT ALT AZI  HRS MIN     R  A    DEC  RANGE
     94  9.4   6371  36 258    9  45   13  3.2   8.9   7496
     99  9.3   6928  41 255    9  50   13 31.8   9.5   7864
    103  9.2   7480  46 251    9  55   13 57.3   9.8   8270
    107  9.2   8026  49 248   10   0   14 20.0  10.0   8702
    
    Some of the Centaurs tumble rapidly and some don't.  I have not
    looked for this one yet.  The payload should maneuver to geosync
    orbit.
    
    On the other subject, Ed and I watched the ISS "skim" the Earth's
    shadow on Friday evening.  At the culmination point with an altitude
    of 60 degrees in our southeast, it was about -3 magnitude.  I tracked
    it for over 3 minutes after that in my 8 inch telescope.  When I lost
    it, it was about magnitude 8 or 9 about 12 degrees up in my northeast.
    The range was about 800 miles.
    
    The seesat program says it was about 0.5 degrees inside the Earth's
    shadow.  That is a "geometric" computation which ignores refraction.
    
    Mike McCants
    Austin, TX
    
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