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    Re: SNO sun-scope collimation collar -- what about vertical?
    From: Frank Reed
    Date: 2010 Apr 3, 12:35 -0700

    As long as the axis of the scope is parallel to the frame, the centering of the sight line is a matter of preference and viewing convenience. If you raise it up from the frame, you will be looking at the reflected image off the clear glass side more so than the mirrored side of the horizon glass. That's a means of reducing the brightness of the Sun's image.

    To verify that the scope is parallel to the frame (which it probably is, and you may have already done this), you can either use an old difficult trick involving observing the angle between two objects more than 90 degrees apart or so (for which see an old edition of Bowditch or similar) or you can use a simple tabletop arrangement as follows: place two supports of the same size on the arc of the sextant. Put a long sight tube --any straight tube-- on top of the supports, or put a decent laser level on top of the supports. Then look through the sight tube or aim the laser at a wall a good distance away and note the location on the wall. Look through the telescope and you should be looking directly at a spot at the same height on the wall. If not, adjust the screws. When they match, the telescope is parallel to the frame.

    Re "CHO" versus the proper "SNO". Sorry, but having studied Russian, I just can't stand that barbaric usage! I'm kidding. :-) It's not really barbaric, but it sure ain't right. It's like writing CCCP for the old USSR.

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