Re: Estimating standard visual magnitude from RCS

From: Vitek, Antonin (avitek@lib.cas.cz)
Date: Tue May 22 2001 - 09:07:25 PDT

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    Matson, Robert wrote:
      
    > Jonathan was inquiring about how to approximate a satellite's
    > visual magnitude when only its RCS is given.  As others have
    > eluded, you can't really.  RCS is very sensitive to the
    > geometry of the object in question. 
    Establishing theoretical mathematical function between the effective
    area (ie. aerodynamic parameter) and observable magnitude is impossible.
    The situation is more complicated as stated in cited e-mail, because
    there is at least one more free parameter in question, namely albedo of
    the object (ie. reflectivity) due to the different materials used on its
    surface (cf. eg. problems of estimating diameters of small Solar system
    bodies). For ordinary materials albedo may vary between 0.95 (polished
    surface) to cca. 0.4 and for space debris it is practically impossibte
    even to quess its value.
    
    The only way is the mentioned one, ie. empirical formula obtained by
    statistical evaluation of enormous amout of observational data. Thanks,
    Robesrt, for doing that.
    
    > so don't know what the 1-sigma error
    > bars were on that value.  
    
    I think this (statistical) dispersion should be rather big.
    
    Due to the 
    --------
    Mgr. Antonin Vitek, CSc.
    Office: Main Library, Academy of Sciences of the Czech Republic
      Narodni 3, CZ-11522 Praha 1 - Phone: +420(2)21403255, fax
    +420(2)24240611
    Home: Kytin 127, CZ-25210 Mnisek p. B., Czech Republic
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    My satellite home page: http://www.lib.cas.cz/www/space.40/index.html
    
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