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    Re: Lunars with Young's formula: always off by several minutes
    From: Frank Reed
    Date: 2018 Oct 31, 06:36 -0700

    Young's formula...? by haversines?? That's probably over-complicating things...

    An easy mistake to make with lunars at the beginning is trying to do everything by "your own method" all at once. The problem is that you can't debug your process --find problems in techniques, tools, algorithms, methodology-- because all the components are piled up together. So why not start with one specific element. Explore it. Make sure that's working... And then you can move on to the next step in the process. Fundamentally, you have two very separate steps in a lunar: the observations and the clearing process. The observation process can be divided into issues with the instrument and, separately, observing technique. The clearing process can further be divided into algorithms (e.g. Young's formula) and calculation methodology (e.g. working on a calculator, building a spreadsheet, using logarithms on paper, and so on). 

    It sounds as if your exploration of resources here (in the NavList archives?) got as far as about 2003 and then stopped abruptly (that's when the late George Huxtable wrote the multi-part essay you referenced). Since 2004, I have made available a simple, easy-to-use web app that lets you clear lunars online fast and accurately. In addition I wrote up in 2004 an essay called "Easy Lunars" that provides an easy methodology for clearing lunars that you can apply on a simple handheld calculator (or equivalent), as well as some observing advice. These and other tools are available on my website here: http://www.reednavigation.com/lunars/

    If you have one or two sample lunar observations that you would like to post, feel free! There are a number of people here who get pleasure from working these things.

    Finally, I teach, what I believe to be, the world's only class in Longitude by Lunars at Mystic Seaport Museum in Connecticut. The class runs fairly often, and if there is enough interest, we'll offer it again in Spring, 2019.

    Frank Reed
    Clockwork Mapping / ReedNavigation.com
    Conanicut Island USA

       
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