It seems that as Roger said it would make the base slanted at a cockeyed angle. And intuitively I'm not sure the hour lines would stay in the proper alignment with the shadow planes. The west side would start to rise and it seems that the shadow planes of each hour would cut through the
You have done a spectacular job. I especially like
your comments. They are very informative and useful
to someone interested in making sundials.
Claude Hartman
35N 120W
Frans W. Maes wrote:
Dear sundial friends,
Some two years ago I published a website in Dutch about the unique Sundial
On Thu, 15 Jan 2004, John Hall wrote:
Hi Ed
The answer is yes, and there is an example of how Longitude correction
might be done in 'Practical Astronomy' by H. Robert Mills on page 106
in the edition I have. To correct for EQT replace the straight hour
lines with analemas and ensure
As a beginner to the fascinating study of gnomonics, let me say first of all
that it was especially rewarding to discover that a list such as this exists,
whereby novices such as myself may consult with professionals and folks of all
levels on matters of our mutual interests in dialing. So
Hi Ed,
As far as I know, any dial with a gnomon parallel to the earth's axis
may be corrected for EOT, Longitude and Daylight Savings Time by
rotating the entire dial around that axis. Since they are all based on
the projection of an equatorial dial.
Hope this helps!
Edley
Hello All.
Dear sundial friends,
Some two years ago I published a website in Dutch about the unique Sundial
Park in Genk (Belgium), a permanent exhibition of classical and novel
sundials.
Finally, the English version is out. Have a look at:
www.fransmaes.nl/genk/welcome-e.htm
I hope you enjoy it! If you
Somewhat off topic, but how do you translate (a) the right ascension of a
star and (b) the current date and time into (c) the apparent longitude of
the star?
-
Hello Frans...
Bravo! I've just spent a happy hour viewing your English version of
the Sundial Park. Your refreshingly honest comments are a pleasure to
read. And the explanations are enormously useful.
Thank you so much for this effort.
Best wishes,
Mac
P.S. What a pity the Sundial Park
Message text written by INTERNET:sundial@rrz.uni-koeln.de
Somewhat off topic, but how do you translate (a) the right ascension of a
star and (b) the current date and time into (c) the apparent longitude of
the star?
Difficult to explain via an e-mail and it is quite tricky. See Jan Meeus'
Hello Ed,
One caution on this rotation technique. As Edley states you rotate the
entire dial around the polar axis. After rotation the horizontal dial plate
will no longer be horizontal. This is the problem with these tilt or
rotation corrections. The resulting dial may show civil time but it
Patrick's advice is correct but I suspect that it is more than Brad was
looking for. Sidereal time is the hour angle of the Vernal Equinox (Aries),
one of the starting lines for the celestial co-ordinate system, declination
being the other. Right ascension for a star is just the distance from
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