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    Re: Sextant Collimation Error
    From: Bill Lionheart
    Date: 2020 Jun 25, 08:20 +0100

    Do you know how big that collimation error is when using a ghost ring
    and not looking through it straight?
    On Sun, 14 Jun 2020 at 18:46, Greg Rudzinski  wrote:
    > David,
    > When making an observation without an optic it is easy to be off on line of 
    sight (collimation)  when using just a ghost ring. A sight tube is a much 
    better way to keep things centered. Remember to apply index error to the 
    artificial horizon sextant reading then divide by 2 before applying the 
    refraction correction. Of course there is no dip correction for height of 
    eye. The beauty of the artificial horizon observation is that there is no 
    uncertainty due to height of eye, anomolous horizon refraction, or 
    perpendicularity. Systematic errors are also cut in half when the observation 
    is divided by 2. So expect LOPs to be closer to the actual position vs. using 
    a natural horizon.
    > Greg Rudzinski
    > View and reply to this message

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