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    Re: Moon 'sights' using Anti Spoof Pro - my numbers are a bit out
    From: Antoine Couëtte
    Date: 2022 Aug 5, 10:26 -0700

    Lance,

    Last contribution I think: this time I am going to simply treat your data as a Moon Fix using your GPS position as DR position.

    UTC date: 02AUG22, GPS position: 42° 49.4'S 147° 15.7'E.

    GPS Anti Spoof Pro (ASP) settings: Body: Moon, LL, sea horizon, no delay, T=11-14°C, P=1007 hPa/mb. Index correction -1.0'.  Height of eye 2.9m.

    01:02:06 UTC ASP Hs=12° 53.1',  Intercept = +0.5 (T) Azimuth = 070.6°

    01:55:07 UTC ASP Hs=21°39.3',  Intercept = +0.6 (T) Azimuth = 060.7°

    04:12:17 UTC ASP Hs=39°18.3',  Intercept = +0.5 (T) Azimuth = 027.2°

    05:55:58 UTC ASP Hs=43°07.4',  Intercept = +0.5 (T) Azimuth = 353.5°

    All LOP's cross in one same point at your observed fix S42°48.9' / E147°16.1' , not far away from home, but on river Derwent this time.

    Conclusions :

    If you were using a sextant, all your sights are all good if not very good for the Moon.

    The comment by Bill Ritchie is certainly quite valid : you might have aimed at "slightly obscured" limb.

    Since you were expecting Moon intercepts very close to 0.1' similar to the ones you are consistently achieving with stars ( " When using stars, a calculator and my known position, I get Ho = Hc to the nearest 0.1', as expected for a known position  "), you cannot be using a regular sextant ( otherwise, let me know which brand of sextant ...) which does not permit this kind of consistent "bullseye" measures.

    You are using a theodolite, aren't you ? ... (which I am too now and then from my backyard for ALL bodies when I want to consistently achieve regular intercepts below 0.1' ...)

    Antoine M. Kermit Couëtte

       
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