I’d said: .
The Shadow-Tip method [has] accuracy is greater at lower latitudes. . You replied: . That's putting it mildly, I think. The method would be OK everywhere around midday or near an equinox but I suspect it's really, really bad if used early or late on a midsummer day at higher latitudes. I'm from 55N, and for that latitude I reckon it could reach as much as 45 degrees off outside of the midday period in summer. . I answer: . Yes, I get 42.7 degrees max error at that date at sunset or sunrise. But you’d know that, and so you’d know that the error will vary from 0 to 42.7, (at least on the summer side, and something very similar on the winter side) facilitating an a reasonably good estimate of how much the error will be at any time, because you know it will be less when closer to the equinox or noon.. . It’s dinner-time now, and so this is just a quick preliminary reply. After dinner, I’ll reply to the rest of your post, and will report the Watch-Method’s errors at some times at the summer solstice at lat 55. By the way, of course AW would be at its best at high latitudes. Michael Ossipoff On Wed, Oct 24, 2018 at 5:25 PM Steve Lelievre < steve.lelievre.can...@gmail.com> wrote: > Hello, Michael, > > On 2018-10-24 8:42 a.m., Michael Ossipoff wrote: > > The Shadow-Tip method [has] accuracy is greater at lower latitudes. > > That's putting it mildly, I think. The method would be OK everywhere > around midday or near an equinox but I suspect it's really, really bad if > used early or late on a midsummer day at higher latitudes. I'm from 55N, > and for that latitude I reckon it could reach as much as 45 degrees off > outside of the midday period in summer. > > I've nearly always gotten very good results with [the Altitude Watch >>> method], though there are combinations of time-of-year and time-of-day when >>> it loses accuracy. Midsummer and roughly mid afternoon or morning. >>> >> Maybe I've misunderstood, the method but I don't understand why > mid-afternoon and mid-morning are the bad times of day. Why is that? I > would expect it to be around noon, when the sun's azimuth can change > significantly for relatively little change in altitude. > > Anyway, your method reminded me of another altitude method - a Shepard's > Dial marked out as a solar compass. I once made one and it worked pretty > well, with a bit of degradation around noon. A Mr. Singleton was the first > person I know of to publish the idea. > Steve >
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