NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Nitpicking on Moon Height Corrections
From: Paul Hirose
Date: 2013 May 29, 22:36 -0700
From: Paul Hirose
Date: 2013 May 29, 22:36 -0700
Antoine Couëtte wrote: > Height of eye is assumed to be zero (i.e. Horizon Dip = 0.000’) and atmospheric conditions are supposed to be standard, i.e. P = 1013.25 mb (or 29.92 “ HG) and T = 10°C (283.15°K , or 50°F). > On Sep 29th 1987, with TT-UT = +55.7s , the Moon Center Coordinates were : > RA = 18h01m47.04s Dec = S -28°43’23.35” At the time of the altitude observation? I have significant discrepancies: 18h01m46.871s -28°43′22.40″ (geocentric apparent place, DE406 ephemeris, IAU 2006/00A precession - nutation). > From Position S-24°04’6 W094°52’6, at UT1 = 23h48m29.0s on Sep 29th 1987, Navigator #1 observes the MOON LL at H = 85°00.0’. He gets: Intercept = 0.0 NM with Azimuth = 180.0° > > His detailed 3D Space MPASD Corrections are as follows: > Refraction = -0.085’ > Augmented Semi-Diameter = 16.306’ > Parallax = +4.994’ > Augmented Semi-Diameter + Parallax = 21.300’ > Refraction + Augmented Semi-Diameter + Parallax = 21.215’ > Geocentric observed height = 85°21.215’ My refraction and SD agree within one digit in the last place. I cannot confirm the other values because my software computes the topocentric coordinates of the body in a different way. Altitude intercept is -0.014′. > From Position S-33°22’5 W094°52’6 at the very same time UT1 = 23h48m29.0s on Sep 29th 1987, Navigator #2 observes the MOON LL at H = 85°00.0’. He also gets: Intercept = 0.0 NM with Azimuth = 180.0° I get azimuth 360.0°, intercept 00.011′. My values are from a lunar distance program for Windows, now in final modification and test, soon to be released. --