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    Re: Polaris isn't so easy!
    From: Jim Thompson
    Date: 2004 Apr 6, 08:28 -0300

    To summarize messages that I've been receiving on and off the list:
    
    1. Polaris is dim enough that it has to be shot later in twilight, reducing
    the window of opportunity because the horizon is worsening rapidly then,
    even as Polaris is becoming brighter.
    2. An artificial horizon (pan of oil) can work, with practice, but it is not
    easy to use initially.
    3. Optimize environmental factors:
    3a. Pick a spot with minimal urban light pollution.  (I was standing beside
    a lighthouse!!).
    3b. Dark adapt eyes carefully, and keep them dark adapted (red flashlight).
    3c. Use AH when there is no wind.
    4. Use a telescope. The 2.5 power will work, but higher power is better,
    though not necessary.
    5. Use a split horizon rather than whole horizon.
    6. Preset the sextant for predicted altitude, or reverse the sextant.  I
    have been trying to bring Polaris down to the horizon, which is my usual
    practice with bodies.  I was losing it about a third of the way to the
    horizon.
    7. Polaris is easy to find at our latitude because it is the first star to
    appear at 45 degrees due north and is "all alone" for a while, until its
    neighbours appear.  But the neighbours are easy pointers anyway.
    8. Practice, practice, practice.  With time shooting Polaris will seem easy,
    but not the first night out, or even the second.
    
    http://jimthompson.net/boating/CelestialNav/Polaris.htm
    
    Jim Thompson
    jim2{at}jimthompson.net
    www.jimthompson.net
    Outgoing mail scanned by Norton Antivirus
    -----------------------------------------
    
    
    

       
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