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    Re: A halo-like rainbow round the Sun: some sextant measurements.
    From: Frank Reed
    Date: 2017 May 17, 06:42 -0700

    Tony, sounds like you saw a halo phenomenon known in English as a "sun dog": https://en.wikipedia.org/wiki/Sun_dog. The angular distance from the Sun is usually given as 22°. By the way, the primary arc of a "common" rainbow is located about 42° from the anti-Sun point. If conditions are right for a rainbow, you can spot one quickly looking for the point with azimuth opposite the Sun and altitude below the horizon equal to the Sun's altitude above the horizon. That's the anti-Sun point. Then sweep out, or imagine, a circle 42° in radius centered on that point. Often you can detect a faint rainbow following this procedure that is not otherwise obvious. 

    Frank Reed

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