NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Captain Cook's Sep 07th, 1773 Lunar revisited
From: Peter Hakel
Date: 2012 Jul 24, 02:30 -0700
From: Antoine Couëtte <antoine.m.couette@club-internet.fr>
To: NavList@fer3.com
Sent: Monday, July 23, 2012 12:25 PM
Subject: [NavList] Re: Captain Cook's Sep 07th, 1773 Lunar revisited
From: Peter Hakel
Date: 2012 Jul 24, 02:30 -0700
Kermit,
I completely agree with you about the value of giving those extra digits for the reasons you describe.
Peter Hakel
I completely agree with you about the value of giving those extra digits for the reasons you describe.
Peter Hakel
From: Antoine Couëtte <antoine.m.couette@club-internet.fr>
To: NavList@fer3.com
Sent: Monday, July 23, 2012 12:25 PM
Subject: [NavList] Re: Captain Cook's Sep 07th, 1773 Lunar revisited
... and by the way, just a little add-on to my recent posts, so everybody on NavList will feel comfortable.
I do acknowledge that when I publish own computation results with so many digits, the RIGHTMOST DIGIT(S) HAVE ABSOLUTELY NO PHYSICAL SIGNIFICANCE AT ALL. Take as an example, my recent following sentence [QUOTE] Cook did observe a reported Sextant Distance of 105°47'04" while he should have observed an actual Distance of 105°47'55"9 [UNQUOTE]
The only aim of publishing 1 (or even - shame on me !!! - 2) extra digits is to offer - to whoever will check his computations and results against my own numbers - such extra digits which can prove quite useful.
A most recent example ? When Paul observed his own height results for both Sun LL and Moon UL [QUOTE] the observed Sun altitude is 3.8' less than the computed value, and the Moon altitude 3.9' less [UNQUOTE], we both almost immediately
made the link to the 3'50" dip correction I initially had omitted, a fact that took me only a matter of seconds to ascertain. However, it is more than probable than such altitudes - taken with a wooden Octant - were recorded to an accuracy certainly no better than 1 ', or even 3', if not 5' or maybe up to 10', we ALL know that, and we also all know why since achieving any kind of deadly accuracy was not that critical for the observed heights themselves.
Same for my indications of the TT-UT I am keeping quoting : +16.4 s here. It is most probable that TT-UT is now known - and will EVER stay so - to an accuracy probably NO BETTER THAN up to 4 seconds of Time, which is equivalent to an uncertainty of 2" on the Moon Coordinates - not bad already for a period 240 years back ! - while the Moon Tables at the time of Cook (1773) were barely more accurate than 20" from what we can cross-check to-day.
However, quoting these NO PHYSICAL SENSE
digits can be very helpful - to only just a few of us I agree - in order to enable checking the consistency - and possible "fine tuning" - of computations, whether they be yours or some colleagues's. To the (maybe vast majority of) NavList Members who might be silently irritated at such a waste of digits, my most sincere apologies.
So, I really think that nobody on NavList should and even is really being abused by such extra digits, no ?
Best Regards
Kermit
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