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    Re: Star Identification
    From: R B Emerson
    Date: 2008 Jul 30, 15:49 -0400
    Er, but there are times when the clouds part long enough to give a couple of shots of "some star", no matter how carefully one pre-computes altitudes and azimuths.  Maybe the LOP crossing angle reeks and it's all less than satisfactory but if it's that or sticking with an old and questionable DR EP, I'll take the sights and be glad of them.  Even if I do view them with some caution. 

    Rick Emerson

    "I'd like to live in Theory.  Everything works there."  - -  Anonymous

    Greg R. wrote:
    --- bruce hamilton <bruce.hamilton@shaw.ca> wrote:
    
      
    Last night, I could get a reading from a single star through a
    single whole in the clouds.  My star identification skills are
    still poor, and those circumstances were beyond me. Is there a
    quick and dirty way to take that single observation and find what
    star I was looking at using the observation, an Almanac a watch and
    calculator?
        
    
    Not to criticize your technique here (and if it works for what you want
    to do, there's certainly nothing wrong with that...), but you're almost
    going about it "backwards".
    
    Usually you'll pre-compute elevations and azimuths of stars *before*
    doing the sights, and then point the sextant accordingly (it's usually
    pretty obvious what star you're looking for, just look for the
    brightest object in the sextant's field of view... ;-)).
    
    Vol. 1 of Pub. 249 works really good for this - they've already done
    the hard work for you, all you need is LHA Aries for the time of the
    sights. From that it gives you a group of seven stars pre-selected for
    your shooting pleasure - even has the 3 that give the best "cut" for a
    fix marked with diamonds, and 1st magnitude stars are listed in ALL
    CAPS.
    
    --
    GregR
    
    
    --- bruce hamilton <bruce.hamilton@shaw.ca> wrote:
    
      
    I just received an A-10 that I got for cheap on E-bay. Well, most of
    one
    as is is missing the averaging mechanism, but as I plan to use it
    with
    my feet firmly planted on the ground, I don't need that bit. I also
    managed to coax a bubble out of it too.  I must say that it is the
    best
    thing for us urban dwellers with no horizon handy. I might get a
    calibrated A-12 next as I love the concept. Put the body in the
    center
    of the bubble and I have a reading. Very nice! I am a bubble sextant
    fan
    now.
    
    I have one question for someone who has used one (A-10) before. What
    is
    the use of the frosted glass that swings over the top of the bubble
    column? Mine has some faint lines on it, but it seems to me that if
    the
    body is in the bubble, no other reference is needed.  As well, it
    seems
    to me if I peek to the left of the view, I could see a natural
    horizon,
    if I had one. Is this possible or a pipe dream?
    
    Another question. Last night, I could get a reading from a single
    star
    through a single whole in the clouds.  My star identification skills
    are
    still poor, and those circumstances were beyond me. Is there a quick
    and
    dirty way to take that single observation and find what star I was
    looking at using the observation, an Almanac a watch and calculator?
    I
    think I found the star in the site plan section of Celest Nav on my
    palm
    pilot, but I would like to be able to do it without.
    
    Thank You
    
    Bruce Hamilton
    Vancouver, BC
    
    
    
        
    
    
    
    
    
      

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