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    Re: Working Analemma
    From: Lu Abel
    Date: 2006 Nov 11, 22:06 -0800

    James R. Van Zandt wrote:
    >
    >
    > Lu Abel  wrote:
    >
    >
    >>  The UPS "analemma" is a stainless steel path about 2 inches wide,
    >>  inscribed at about 10 day intervals.  It was constructed based on a
    >>  set of plans provided by a professor who had to very carefully
    >>  calculate the distortions induced by the location of the mirror.
    >>  Although it hasn't been in service for a full year, I hear it's
    >>  doing fine so far....
    >
    >
    > I assume that it works at solar noon each day.  I wouldn't be
    > surprised if they need to post a conversion table between solar time
    > and what the clocks are set to.
    
    By playing with a wonderful web site that maps locations given by
    latitude and longitude into most common mapping web sites, I reckon the
    L/Lo of the analemma to be N 47d 15.82m,  W 122d 29.01m.  So it's
    definitely west of the time zone meridian.
    
    The tour guide didn't state whether the analemma worked at local noon or
    time zone noon (which occurs roughly 10 minutes earlier); he was a
    chemistry prof and really didn't understand the mechanics.  I took one
    fellow visitor who seemed particularly inquisitive aside and explained
    the basics of an analemma.
    
    Yes, the sun would rise a bit between zone noon and local noon, but I
    not sure it's significant enough to require recalibration of the analemma.
    
    The obvious thing to be concerned about is the hour's correction for
    Daylight Time (Summer Time to Europeans).
    
    Lu Abel
    
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