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Re: Star finder, 2102-D, further modification
From: Gary LaPook
Date: 2010 Nov 09, 11:16 -0800
From: Gary LaPook
Date: 2010 Nov 09, 11:16 -0800
On 11/9/2010 8:22 AM, Luc Desmedt wrote: > The book published by David Burch (star-finder book) explains why the > ecliptic have not drawn on the 2102-D but I can not find the page > today (I'll read it again) but I guess it changes with the precession > of equinox? Yep, that's the problem and in only 13,000 years an ecliptic drawn on the 2102-D will be off by 180°. If you are worried about this then use a pencil and, to maintain one degree accuracy, simply erase the ecliptic and draw in a new one after 72 years. But wait, the whole star base will be off by one degree after 72 years since the plotted positions of the stars are based on the position of the equinox at the time that the 2102-D was manufactured so you will have to buy a new star finder in 2082 A.D. (or earlier, depending on how old your 2101-D is already.) In fact, giving it more thought, the ecliptic will remain in the correct place (so you won't have to redraw it) but you will have to replot all the stars. gl
