Hi all
I’ve just finished a new paper sundial, it is available as app 41,
www.sundialatlas.eu/atlas.php?app=41
It is like an hemi-sphere but realized with an half truncated icosahedron.
To simulate the sphere I used this archimedean solid, also known as fullerene,
with 32 faces: 12 pentagons and 20 hexagons.
It is also rendered with the image of the Earth (image credit of NASA – Goddard
Space Flight Center)
Setted any coordinates, the app turns the solid so that the correspondent point
becomes the lower point, on the vertical axis trough the center of the solid,
then it dissects the solid with an horizontal plane to get the pseudo
hemisphere.
The app returns a pdf of 3 pages. The 1st with the section, the 2nd with the
development of the half solid and the 3th with the basement and the gnomon.
The edge of the gnomon reaches the center of the solid and shows the time in
the concave pseudo hemi-sphere where there are also drawn the hour lines.
The edge of the shadow shows the time but also the point on the Earth where,
moment by moment, the Sun is at zenith.
The algorithm is quite complex, the time to get the pdf may be about 18 seconds
(server time) for half analemma every hour to about 72 seconds for the whole
analemma every 5 minutes (not very useful). A common case of half analemma
every 10 minutes require about 30 seconds.
Important note: the browsers have embedded a pdf reader to show these files but
they are not very accurate. May be you see lines slightly out of position or
you don’t get printed the dotted lines. The solution is very simple, save the
pdf in your computer, then open the file with Acrobat Reader, it is fully able
to show and print the whole content.
On the top face you can also read the amplitude and the daylight arc.
I verified the app with many locations, everything seems ok but your reports
will be welcome.
Enjoy the summer solstice on app 41, ciao Fabio
Fabio Savian
[email protected]
www.nonvedolora.eu
Paderno Dugnano, Milano, Italy
45° 34' 10'' N, 9° 10' 9'' E, GMT+1 (DST +2)
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