A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
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