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    Re: It's four-planet fix time...
    From: Lu Abel
    Date: 2018 Aug 5, 17:21 +0000
    By convention:

    Hs (usually abbreviated hs) is the raw sextant reading

    ha is hs adjusted for index error and height of eye -- ie, what someone with a perfect sextant with his/her eye at exactly sea level would observe.

    Ho is ha adjusted for refraction and other effects -- ie, a perfect observation in an atmosphere-less earth.

    So:  s = "sextant"  a = "apparent"  o = [perfect] "observation"


    We compare Ho to what one would get for an Ho if one were at one's assumed position; this is called Hc (c = "calculated" [if I were at where I think I am])


    On Sunday, August 5, 2018, 10:02:20 AM PDT, Antoine Couëtte <NoReply_Couette@fer3.com> wrote:


    RE : Its-fourplanet-fix-time-Rudzinski-aug-2018-g42485

    Dear Greg,

    Thanks for your shooting report and drawing.

    What do "Hs" and "Hc" stand for ?

    "Raw" instrument reading ? Which I suspect for "Hs"

    Corrected for Bulb Error ? (Which I suspect for "Hc" vs. "Hs") hence we would still need to correct for atmospheric refraction and parallax,

    Corrected for Bulb Error and atmospheric refraction ? Hence we would still need to correct for parallax ...

    Corrected for everything including parallax (i.e. geocentric value) ?

    Thanks in advance.

    Expecting to shoot all of them on the Western Coast of France shortly, maybe when Lady Moon is back in the night sky ...

    Very Best Regards

    Antoine

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