Re: Astronomical Quiz difia

From: Tim Rogers (timrogers@charter.net)
Date: Tue Apr 19 2005 - 21:08:24 EDT

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    Just for clarification, would this be true for any location on the planet?
    When you say "when observed from directly below on the earth's surface," do 
    you mean *just* below the earth's surface (centimeters or inches?)
    
    Tim Rogers
    Sugar Hill, GA  USA
    
    
    ----- Original Message ----- 
    From: "Jeff Umbarger" <jumbarger2000@yahoo.com>
    To: <SeeSat-L@satobs.org>
    Sent: Tuesday, April 19, 2005 7:19 PM
    Subject: OT: Astronomical Quiz difia
    
    
    > Hey All,
    >     So, watching satellites the other night I came up
    > a with an idea that I believe is correct, but I want
    > to bounce if off others in the group to see if I'm on
    > the right path. There is a point in the stellar field
    > (that is described with coordinates Right Ascension
    > and Declination), that when observed from directly
    > below on the earth's surface, can never be seen in
    > complete darkness. You can either name the RA and Dec
    > or the name of the constellation. Please respond back
    > to me and not to the group. I'll post the answer if
    > enough folks are interested.
    >     And now a slightly more on thread notion: I
    > learned of a formula that tells when an observers
    > Civil Twilight (when the Sun is 6 degrees below the
    > horizon) is shortest during the year (when Civil
    > Twilight follows Sunset in the shortest amount of
    > time) based on the observer's latitude. The formula
    > is:
    > The date in March = March 21 - 1.0146 *
    > arcsin(0.1427*sin(theta))
    >
    >     where theta = the observer's latitude.
    >
    > This, of course, is the shortest visual satellite
    > observing night of the year - on average. This formula
    > came from a magazine called The Bent, put out by Tau
    > Beta Pi - an engineering honor society.
    >
    >     Regards,
    >          Jeff Umbarger
    >          Plano, TX USA
    >
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