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    Re: Moon - Antares
    From: Frank Reed
    Date: 2009 Jan 24, 18:11 -0800

    
    "If knew roughly where I was and had some instrument with horizontal and 
    vertical cross hairs, I could mark when the star had the same altitude or 
    azimuth as a limb of the moon.  My almanac or computational tool could then 
    be used to determine the UT for that event."
    
    Yes, and thinking about it further, as long as the ecliptic is relatively 
    vertical (within let's +/-30 degrees) at the time of the observation, it 
    ought to give a fairly good value for GMT. The usual objection to using lunar 
    altitudes for longitude is that observations of altitudes are much less 
    accurate than observations of lunar distances, by a factor of five or even 
    ten. But if you measure the altitude of a star *and* the Moon and wait for 
    them to be nearly identical, then most sources of error are cancelled out. On 
    land you could even dispense with a sextant and do this by lining the two 
    objects up along the roof line of a nearby building, assuming it's level. 
    With a sextant, you could take a series of sights over several minutes 
    alternating between Moon and star. Then graph them to find where they cross.
    
    I suppose if you had a vertical reference of some sort, like the side of a 
    building, you could do the same thing with azimuth...
    
    -FER
    
    
    
    
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