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Re: Hughes Tables.
From: Douglas Denny
Date: 2009 Jul 16, 21:05 -0700
From: Douglas Denny
Date: 2009 Jul 16, 21:05 -0700
Hughes Tables were a re-assessment of all the other tables in use with a re-arrangement of the tabulations for better use for air navigators. The explanation on page xxxi goes into some detail:- " It was originaly proposed to base Table I on the values of K and A given by Weems (based on Ogura up to Latitude 65) and the values of D and Z1 given by Dreisenstok. However, in the course of the proof reading, comparisons were made with published tables (Aquino, Dreisenstok, Gingrich, Ogura, Pinto, Smart and Shearme, and Weems) showed that none of them, with the exception of Aquino, were reliable. In order to present tables whose error was less than one unit of the last decimal in K and A, and less than half a unit in D and Z1, many discrepancies had to be investigated by new calculations, especially of the quantity A; the entire portion from latitude 62 to the pole was recomputed. It is curious that an obvious check has been missed by by all the other authors except Aquino. " ======================== Working the values you gave: It is not clear what longitude you wish to use to give a local hour angle of a whole degree for use in the tables. I used the nearest which gives an LHA of 4 degrees. You gave Lat 40 N. Long 77W. fomalhault on 13th July 2009 at 09-00Hrs. I found the following:- Using ICE 0.51 for the ephemeris data for formalhaut for 13th July 2008 09-00Hrs:- GHA is 81-49.6 Dec is S. 29-34.0 (N.B. ICE gives an Hc for the Lat40 Long 77W of 20-17.3) Working with Hughes:- We have:- GHA 81-49.6 long 77-49.6 West (-) LHA 04-00 K: (Table I) +39-04.1 declination -29-34.0 (add to form K alt d) (K alt d) 68-38.1 (entered into Table II for 'B') A: (Table I) 00064 'B'(Table II) 43850 (add) forms: 'C' 43914 ...... re-entered in Table II gives Altitude: 21-20'.0 =========================== Douglas Denny. Chichester. England. --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---