Another suitable method to know the exact sun position, and therefore to find North, is to use the Android app "Sol et Umbra".
It was described in the article "A Mobile Gnomonic Tool For Android Devices", The Compendium, vol. 20, n. 2, June 2013. And it is available from Google Play Store at https://play.google.com/store/apps/details?id=gian.gnomonica.SolEtUmbra Gian Il giorno ven 19 feb 2021 alle ore 00:46 Steve Lelievre < [email protected]> ha scritto: > Ed, > > To find True North, many dialists use Hindu Circles (also known as Indian > Circles). It's worth reading up on the method if you want to learn a bit of > theory about the sun's daily path as it relates to sundials. There's a > brief description of the method at bullet point 4 at > https://www.mysundial.ca/tsp/true_north_south.html but for a full > explanation you'll need to refer to sundialing books or websites. > > If you prefer to use a magnetic compass, you can do so by adjusting for > magnetic declination. There's a handy tool for figuring out your local > magnetic declination at https://www.geomag.nrcan.gc.ca/calc/mdcal-en.php. > > In practice, a simple and reliable method for finding North is to use > software to tell you what the sun's azimuth is at a certain instance during > the day, and to use the shadow of a perfectly vertical rod or a plumb line > (if you are out of the wind) as a pointer. A convenient time to do this is > when the sun is due south because that is when the shadow of the rod or > line points due north (in the Northern hemisphere). At > http://www.suncalc.org there is a suitable webpage (and also an Android > app called SunCalc) for telling you the current solar position. Another > option is my SDN (for Solar Data Now) offering, suitable for a phone's > browser or a desktop browser. It is less sophisticated than SunCalc but > should also do the job. The link is https://www.gnomoni.ca/sdn > > The above methods are for finding North. If your need is only to check > that a sundial is correctly aligned, use the SunCalc or SDN to tell you the > current solar time at your location, and turn your sundial to match. > > Steve > > > > > > On 2021-02-18 1:04 p.m., Ed wrote: > > I know this is a basic question for most here but I am just trying to > figure this out I have built a few prototypes out of cardboard. > I am lat long 30.730401 north > longitude 97 degrees 41.83 west > Thanks Ed > > ---------------------------------------------------https://lists.uni-koeln.de/mailman/listinfo/sundial > > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > >
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