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NPMAS club meetings, first Wednesday   6:30 to 8:30pm  Neville Public Museum 210 Museum Place, Green Bay, WI 54303

 

The Stellar Magnitude System

by Alan M. MacRobert, Sky and Telescope Magazine

 

 

Star Magnitudes

  • RigelCapellaArcturus, and Vega are magnitude 0
  • Sirius shines at magnitude –1.5
  • Venus reaches –4.4
  • Full Moon is about –12.5 
  • Sun blazes at magnitude –26.7.

 

Photometric Systems [UBVRI]

  • Negative-Magnitudes (< 0)
    • U encompasses the near-ultraviolet
    • B is blue
    • V corresponds fairly closely to the old visual magnitude
  • Positive-Magnitudes (> 0) 
    • R standard red magnitudes
    • I is  near-infrared magnitudes.

 

Color Index (B magnitude minus the V magnitude)  The difference between a star's photographic and visual magnitude 

  • positive for yelloworange, and red stars,
  • negative for blue ones."

 

Absolute Magnitude Scale

  • An object's absolute magnitude is simply how bright it would appear if placed at a standard distance of 10 parsecs (32.6 light-years)

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