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    Re: Celestial a Black Box?
    From: Lu Abel
    Date: 2016 Jan 17, 22:55 +0000
    Interesting.   I think the very first step (which this person seems to not have done with clarity) is to differentiate between "hardware" (sextant mirrors, chronometers) and "software" (NAs, sight reduction methods). 

    When I buy a GPS, includes both hardware (some chips forming a receiver and a computational engine) and software (software that can use the computational engine to reduce the received signals into a position).

    In celestial we buy the hardware (sextant, chronometer) but then must confront the "software."

    How many of us truly understand the mathematics behind a tabular reduction method (for example, NASR)?  Few.   So we just follow steps -- an algorithm -- that produces an answer at the end.  Even the Law of Cosines, the closest to pure mathematics, is truly understandable by only those who have taken spherical trigonometry.

    So I guess one could claim sight reduction is a "black box," it's just that a human being has to provide the computational power (whether by table-lookup or by scientific calculator) to make the algorithm provide an output.

    From: Frank Reed <NoReply_FrankReed@fer3.com>
    To: luabel@ymail.com
    Sent: Sunday, January 17, 2016 2:17 PM
    Subject: [NavList] Celestial a Black Box?

    Quoting an experienced navigation instructor:
    "I now make it a point to all navigators that sextant, chronometer and tables comprise just as much of a 'black box' as does satellite navigation. Has anyone silvered a mirror lately in an emergency, or perhaps repaired a chronometer? Celestial navigation is merely an old fashioned 'black box' requiring a bit more of the navigator..."
    Is this a fair statement today? Is celestial a 'black box'? Just curious to hear opinions on the matter.
    Frank Reed

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