Rosetta fly by: about magnitudes

From: Bram Dorreman (bram.dorreman@skynet.be)
Date: Wed Mar 02 2005 - 09:20:24 EST

  • Next message: Kevin Fetter: "Re: Rosetta fly by: about magnitudes"

    On my question:
    
    > > We in Belgium and Netherlands like to try and observe Rosetta
    > > during its fly-by. Therefore we need positions of this
    > > spacecraft with respect to the starry sky and predicted for
    > > our specific locations. Who knows how to obtain these?
    
    I got a very helpful reply from Ted Molczan and others:
    
    > Go to: http://ssd.jpl.nasa.gov/cgi-bin/eph
    >
    I went to this URL and was able to calculate topocentric predictions. They
    look great.
    The only thing I missed was specification of stellar magnitude.
    
    Who can tell me the formula to calculate the stellar magnitude from a self
    defined absolute magnitude (phase 90 and distance 1000 km), range and
    sun-target-observer angle?
    
    Another question: what might be a reasonable value for Rosetta's standard
    magnitude?
    
    Thanks in advance,
    
    Bram Dorreman
    COSPAR 4160
    51 16' 45.5" N  5 28' 36.6" E (WGS84) 35 m
    
    
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