Tabulated GHA and v Correction Factor:
For the Sun, the Moon, or a planet, extract the value for the whole hour of GHA corresponding to the sight. For example, if the sight was obtained at 13-50-45 GMT, extract the GHA value for 1300. For a star sight reduction, extract the value of the GHA of Aries
, again using the value corresponding to the whole hour of the time of the sight. For a planet or Moon sight reduction, enter the v correction value. This quantity is not applicable to a Sun or star sight. The v correction for a planet sight is found at the bottom of the column for each particular planet. The v correction factor for the Moon is located directly beside the tabulated hourly GHA values. The v correction factor for the Moon is always positive. If a planet’s v correction factor is listed without sign, it is positive. If listed with a negative sign, the planet’s v correction factor is negative. This v correction factor is not the magnitude of the v correction; it is used later to enter the Increments and Correction table to determine the magnitude of the correction.
Tabulated Declination and d Correction factor:
Obtain the tabulated declination for the Sun, the Moon, the stars, or the planets from the daily pages of the Almanac. As you allready mentioned declination values for the stars are given for the entire three day period covered by the daily page of the Almanac. The values for the Sun, Moon, and planets are listed in hourly increments. For these bodies, enter the declination value for the whole hour of the sight. For example, if the
sight is at 12-58-40, enter the tabulated declination for 1200. There is no d correction factor for a star sight. There are d correction factors for Sun, Moon, and planet sights. Similar to the v correction factor above, the d correction factor does not equal the magnitude of the d correction; it provides the argument to enter the Increments and Corrections tables in the Almanac. The sign of the d correction factor, which determines the sign of the d correction, is determined by the trend of declination values, not the trend of d values. The d correction factor is simply an interpolation factor; therefore, to determine its sign, look at the declination values for the hours that frame the time of the sight. For example, suppose the sight was taken on a certain date at 12-30-00. Compare the declination value for 1200 and 1300 and determine if the declination has increased or decreased. If it has increased, the d correction factor is positive. If it has decreased, the d correction factor is negative.
d correction: Enter the Increments and Corrections
table with the d correction factor discussed above. Extract
the proper correction, being careful to retain the proper