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    Re: More on 2102-D & Radar Plotting Sheet
    From: Patrick Goold
    Date: 2010 Oct 19, 20:37 -0400
    Forgive this intrusion of a neophyte into the learned ranks.  I have followed this and related threads with interest.  Much of it remains obscure to me.  Is there an archived thread in which the basics of 2102-D are explained?


    On Tue, Oct 12, 2010 at 8:56 PM, Greg Rudzinski <gregrudzinski@yahoo.com> wrote:

    This version of the 2102-D and radar plotting sheet (see linked images) has GHA of Aries, date, and day going clockwise and zone time going counter clockwise. The zone time result requires correcting for the difference between the observers longitude and the zone meridian.

    Use the red template to plot the Sun onto the 2102-D base disc with the current day's declination and time of meridional passage from the Nautical Almanac. Set Aries to month and day on plotting sheet, set red template to time of meridional passage, mark disc through slot at the correct declination.

    Now the 2102-D is ready to get civil twilight time and sky:

    1. Set Aries to month and day.
    2. Rotate latitude template so that the Sun is 5° to 10° below zero altitude.
    3. Read zone time of civil twilight and select stars.

    Image examples are for 12 October 2010
    -meridional passage Sun plot.
    -civil twilight template set.

    Greg Rudzinski
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    Linked File: http://www.fer3.com/arc/imgx/IMG_0191.JPG
    Linked File: http://www.fer3.com/arc/imgx/IMG_0195.JPG

    Dr. Patrick Goold
    Department of Philosophy
    Virginia Wesleyan College
    Norfolk, VA 23502
    757 455 3357

    " The very fact of participating in a process that is universally recognised to be useless is harmful, for everyone who does so is 'only obeying orders' for the sake of his own peace and quiet and for the sake of his career; in other words, by taking part, he has already lost some of his integrity."  Theodore Dalrymple
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