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    Re: Geometry of SNO-T
    From: George Huxtable
    Date: 2004 Oct 14, 13:13 +0100

    Bill wrote-
    >I had posted a question a while back, and have received no response.  Since
    >Alex seems to have a good grasp of this now, I will ask him and others to
    >address it.
    >"If the front-silvered mirror is no longer on the axis of the rotation, will
    >this affect the sextant's performance?"
    >I admit my ignorance.
    >What I think I know is that if I scribed a line on the index mirror at it's
    >axis of rotation, and the plane of that mirror was on the axis, that line
    >would appear at the same elevation in the horizon mirror as I moved the
    >I also think that if the plane of the index mirror moved off the axis, that
    >line would move vertically as I moved the arm.
    >From the reference point of the angles of the index and horizon mirror, no
    >problem, that relationship will remain the same.
    >From the reference point of reflection, so what if the area of the mirror
    >reflecting or the body changes,  Angle in, angle out.
    >This is as far as my skill sets get me.
    Bill, you got a response, but presumably you missed it. True, it was buried
    rather deep within a message. It was sent by me at 12:07 on 13/10/04 (GMT +
    1:00), threadname "perpendicularity" and read-
    "As far as actual measurement of celestial angles is concerned, I don't
    think the precise "fore-and aft positioning of the plane of the index
    mirror matters a damn, so makers may "perhaps not take that positioning
    very seriously.
    contact George Huxtable by email at george@huxtable.u-net.com, by phone at
    01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy
    Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.

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