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    Re: Position from altitude and azimuth.
    From: Robin Stuart
    Date: 2020 May 17, 05:17 -0700

    Bill,

       The first sheet of the Littrow map shown in my earlier post covers all points within ±90° of longitude around the central meridian with the caveat that points get pushed to infinity approaching the poles. If the intersections of the isoazimuth and small circle of equal altitude are within 90° of longitude of the Geographic Position (GP) of the star they will fall on the first sheet and therefore be visible on the map as shown otherwise they fall on the second sheet "behind" the first.

       Of course it is assumed that the Littrow map would be redrawn with the central meridian running through the GP of the star rather than the Greenwich meridian. I would guess that under the Littrow projection small circles of equal altitude become ellipses but haven't proved it,

    Regards,
    Robin

       
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