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    Re: Compass correction using sunrise
    From: Frank Reed
    Date: 2022 Jun 28, 08:21 -0700

    David Pike, you wrote:
    "William Bligh is believed to have had amplitude tables with him in Bounty’s Launch"

    He may have, but they didn't need them. In the tropics and assuming declinations in the Sun's range, the rising azimuth of a body is very nearly 90°-Dec (where Dec is signed), and the setting azimuth is nearly 270°+Dec. The error from this approximation for Sun azimuth checks (at altitude zero) during the open boat voyage would have been negligible -- about 0.6° at the beginning and 0.3° at the end. For stars, they had Orion setting not long after sunset, and Betelgeuse would have yielded nice azimuth checks every day. 

    Frank Reed

       
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