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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
GHA Aries and GHA/Dec Sun
From: Bill Murdoch
Date: 1997 Dec 10, 3:45 PM
From: Bill Murdoch
Date: 1997 Dec 10, 3:45 PM
I have received a few notes about the GHA Aries formula that I want to share with the group. The hour in the example is copied onto the hour line line incorrectly. It was a typo. The calculations reflect the hour at the top of the form and seem to be correct. The form is a lot easier to figure out when printed in a typewriter font. One person had problems with the equals sign and the degree symbol that I used. His computer displayed them as "equal bee three" and "equal bee oh". If you have that problem I can send you a copy as a Word file. Just let me know. It is also possible to calculate the GHA and declination of the Sun to a useful accuracy by a similar method. The moon and planets are a little much. (In fact the Sun may also be a little too much to do without a programmable calculator.) Based on the request for a Sun form, I put this together last night. It has not been well tested, so there may be some boner left in it. Like the Aries form there is one blank and one filled in with a worked example. The accuracy is about 1', maybe a little better. (Remember the Nautical Almanac is only good to 0.25' for the Sun with the biggest errors occuring in late December and early January.) The calculations are based on a 0.01 degree formula from the Astronomical Almanac. Let me know what you think.