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    Re: Accuracy question: kneeling or standing
    From: Frank Reed
    Date: 2014 Feb 24, 12:49 -0800


    As David Fleming has already stated, the main advantage of getting closer to the artificial horizon is simply field of view. The angular field of view is inversely proportional to distance from the mirror or reflecting fluid. And a bigger field of view just makes it easier to find your target.

    Note that this isn't really a kneeling versus standing question. You could just as well put your artificial horizon on a solid support in front of you maybe a foot below your height of eye and remain standing. On the OTHER hand, there may also be independent advantages to sitting down. Lunarians were often advised to find a comfortable spot to sit or even lie down. I've had good success sitting so that I can rest an elbow on a rock or even my knee.

    I meant to reply to one of your earlier messages about lingering errors in some of your observations. You had said that you used a "set and wait" approach: setting the sextant to an angle a little greater than double the altitude and then waiting for the two images of the Sun to make contact. You said you had a consistent error in this process. So have you tried it with a rising Sun? Set to a lower angle and wait for the images to separate. Do you get the SAME consistent error, or does the error now occur in the opposite direction? Also, on many sextants, the shades are insufficient in the horizon direction to observe the reflected Sun comfortably. If the Sun is at all unpleasant to look at from glare, then you will not be able to make a good contact. Try different shade combinations. And try these same artificial horizon observations with the Moon or Jupiter. And again, try some Moon-Jupiter angles (technically "lunars" but you don't need to worry about that --angles are angles).


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