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    Re: Longitude by lunar and solar transit
    From: Geoffrey Kolbe
    Date: 2014 Jun 4, 06:21 +0100



    On Wed, Jun 4, 2014 at 1:21 AM, Peter Monta <NoReply_PeterMonta@fer3.com> wrote:

    Hi Geoffrey,
     
    Doesn't that mean that the expected accuracy in longitude is +/- 15 degrees...?

    :-)  Yes, one needs to know where the meridian is (on the theodolite horizontal scale) to high accuracy, but observations can still be off-meridian.  This 15-degrees thing is apparently for second-order effects like changes in the lunar diameter over the course of an hour or two.

    Cheers,
    Peter


    Ok, I see what you are saying - though I am not sure that is what Chauvenet was saying. He was talking about observations being taken by travellers who were pushed for time and could not hang around to find out where the meridian was to high accuracy. He was saying there is little loss in accuracy through (effectively) observing on azimuths between 165 and 195 degrees.... wasn't he?
       
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