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    Greenwich date and time?
    From: Mike Freeman
    Date: 2017 Apr 30, 22:32 -0700

    To assist on this occasion it might be handy if you have a copy of Celestial Navigation for Yachtsmen Mary Blewitt Tenth Edition ref page 46. However I will try to explain my confusion......

    Star sights 7th Dec 1990

    Time given as Standard time +10.  It is clear this is time zone -10 from DR N40 E153 and from following examples.

    7 examples given but I refer to only 1 

    Calculation for GHA Aries

    Quote from book.... "Standard time correction and watch error for all sights + 10h 5s"

    Watch  03h 44m 15s

    UT       17h 44m 10s

    GHA Aries  331 12'.3 + increments

    Above GHA Aries is correct for 7th Dec UT 17h however having applied correction for zone time & watch error at Greenwich it is not yet 7th Dec. It is in fact still 6th Dec. In which case GHA Aries for 6th Dec UT 17h is 330 13'.2. I may be unaware of a convention here. Maybe it is correct to anticipate and indicate the date after the zone time correction? Perhaps it is a mistake in the book? Perhaps navigators have their own way of doing things?

    Look forward to replies



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