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Gnomon Applet

	Check your time zone offset and the local time.
	Click the applet first! Enter latitude in decimal degrees, northern positive, southern negative, and press return key, enter longitude in decimal degrees, eastern positive, western negative, and press return key.
	Enter gnomon height, and press return key.
	You may use the keys "m", "d", "h", "n" to increase the month, date, hour, minute, or Shift key and "m", "d", "h", "n" to decrease month, date, hour, minute !
	Check a box to set the direction of the shadow to East (azimuth 90°) or West (azimuth 270°).
	Select from the "Details" menu to set the grid size.
	Hold down Command key and click into the grid plane to change the gnomon position.

More of my sundials

This type of sundial has a vertical rod (gnomon, height H) casting the shadow on a horizontal plane. The shadow of the gnomon's top (point P) is used to read the time (and the date).   Mearuring the length of the shadow near the prime vertical (azimuth angle 90° or 270°) the geographic latitude can be computed. h2 = arctan(H/x2), h1 = arctan(H/x1), dh = h2 - h1 = arctan(H/x2) - arctan(H/x1) Details: Prime Vertical Applet      Web Links Analemma - The solar tracking software Project The Analemma (Bob Urschel) Ausführliche astronomische und mathematische Darstellung Wanderung der Mittagsposition im Verlauf eines Jahres (David Przewozny) The Analemma Project (Steve Irvine) The Analemma Sundials on the Internet Deutsche Gesellschaft für Chronometrie e.V. Sundial Links (Daniel Roth) Shadows (François Blateyron) A great sundial program for Windows (download, freeware) Sundials on the Internet - Sundial Design Software Die Lebende Sonnenuhr (AstroMedia*Verlag) North American Sundial Society Fachgruppe Uhren (Förderkreis Industrie- und Technikgeschichte) Sonnenuhren - Unterrichtshilfen für Schüler und Lehrer Virtual Sundial   Please visit my GeoAstro Applet Collection   Last Modified: 2011, Jun 29 © 2011 Juergen Giesen