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    Re: Orion North Arrow
    From: David Pike
    Date: 2022 Jan 13, 13:07 -0800

    Frank Reed you wrote: You have probably not tried the Orion North Arrow under the real sky. You have convinced yourself in your armchair that it's impossible so why bother stepping outside to try it? Ah, well, the reason you must experiment outside is because three dimensions is different from the two-dimensional flatland of your computer screen. Even the 3-dim illusion of a planetarium dome is not up to the task. Give it a go. You'll see that it works beautifully.

    I have been outside and tried it many times and almost got my appendages frozen off for my trouble.  I’ve just tried it again, and the tail-end of the arrow allowing for the 8 degree’s twist, which is beneficial, still crosses my horizon at 160° true.  If I was made from rubber and could bend over double, my thumb would no doubt cross my horizon behind me at 340°, not much use to the night navigator.  By chance I might come across Polaris on the way over.  Then I could go down vertically (because Polaris is always on your meridian) to have a north point on my horizon to operate by.  It depends on what you want the arrow for.  Let’s forget the 7 or 8 degrees for the moment.  If you want to know where the North or South Celestial pole is, that’s fine.  I’ve sailed overnight from the Humber Estuary to Whitby with a failed compass light with Polaris sat neatly on my starboard spreader. Holding a torch in your mouth gets a bit tedious, and there’s always the chance you might swallow it.  If you want a reference point on your horizon to steer by, the arrow is of less value because then you want to know where your own meridian lies, not the arrow’s.  The sword’s meridian (anti clockwise through 8 degrees) only crosses your horizon on south if your latitude is zero or the sword is vertical (i.e. due south of you in any case).  US bloggers and certainly a Trinidadian might not notice this, because they’re close enough to the Equator for the error to be acceptable, but the further north you go the difficulties become obvious to the careful outdoor observer.  DaveP

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