The North Star (Polaris) is 0.73 degrees from the true north celestial
pole. I would think that sighting on Polaris would be good enough for
aligning most sundials.
For those on the Sundial List, if greater accuracy were desired:
1. Take the average of two sightings 12 hours apart (when the nights are
long, in autumn or winter), or
2. With a star chart, ephemeris or planetarium software as a guide, take a
reading when Polaris is due east or west of the pole to get the exact
elevation of the gnomon. Take a reading when Polaris is due North or South
of the pole to get the proper azimuth.
To sight to this accuracy without an optical telescope one might try open
sights such as those used by the astronomer Tycho Brahe in the 16th
century. They can be precise to better than a sixtieth of a degree.
Gordon Uber
At 05:23 PM 2/13/02 -0500, you wrote:
Hello,
I am checking the facts in a garden article to be published soon, and our
writer says that in the Northern Hemisphere, you can find the correct
gnomon angle for your latitude by aiming the gnomon at the North Star. I
know you must align it with the earth's North/South axis, but is simply
aiming for the North Star enough to make the dial accurate at your latitude?
Thank you so much for any clarification you can provide.
Amanda
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Gordon Uber [EMAIL PROTECTED] San Diego, California USA
Webmaster: Clocks and Time: http://www.ubr.com/clocks
