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Re: (meteorobs) Estimating magnitudes



In a message dated 12/15/01 5:45:34 PM Eastern Standard Time, 
chall@cyberusdot ca writes:

<< Each month, in our newsletter NAMN Notes, we also give the brightness of 
the
 planets.  Note that the planets do change in brightness!  For December, yes,
 it is -2.7, according to the RASC Observers Handbook, published by the Royal
 Astronomical Society of Canada.  By next July, though, it will have gotten
 fainter, and will only be -1.8.
  >>
Cathy --

    You (and everyone else) should be aware of the fact that in the 2001 RASC 
Observer's Handbook, there was a significant error regarding the apparent 
brightness of the planet Saturn.  Traditionally, the magnitudes of the 
planets were always taken from the Astronomical Almanac of the U.S. Naval 
Observatory, but apparently, in 2001, the gentleman who writes "The Sky Month 
by Month" section (David Lane) utilized a different computer software program 
to produce the 2001 planet magnitudes.  In the case of Saturn, the published 
figures were found to be too bright by as much as 0.4 to 0.5 magnitudes!  

    As an example, on December 11 in the 2001 Handbook (page 80), Saturn's 
magnitude was listed as an overly-bright -0.9 (rivaling Canopus), when it 
really should have been listed as -0.4.  

    Earlier this year I had contacted the Handbook's Editor, Rajiv Gupta, to 
inquire about this.  He quickly responded by apologizing for the error and 
assuring me that in the 2002 Handbook that the planet magnitudes would again 
be based solely on the U.S. Naval Observatory data.

-- joe rao
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