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    Sextant mirror silvering
    From: George Huxtable
    Date: 2006 Nov 8, 13:09 -0000

    Frank wrote in [NavList 1642] Re: Don't do this to a sextant
    
    | While I'm thinking of it, sextants usually work without serious
    problems
    | even with mirrors that have lost 10 or 20 percent of the silvering.
    Since the
    | focus is at infinity, a few blemishes eight inches away don't really
    cause any
    | problems. I have an octant from c.1830 that works fine despite
    missing  about
    | 20 percent of the reflective material on both mirrors.
    
    I can imagine a potential problem, in that case, when taking altitudes
    of stars.
    
    There may be an intended star, reflected as normal in the index
    mirror, which may perhaps be confused with a brighter star, rather
    overhead and somewhat behind the observer's head, seen through the
    holes in the silvering. Can that happen, in practice?
    
    George.
    
    contact George Huxtable at george@huxtable.u-net.com
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    
    
    contact George Huxtable at george@huxtable.u-net.com
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    
    
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