PLANETS - To calculate the GHA, DEC, and LHA of a planet is about the same as the
sun, except you have one more correction. The "V' correction is found the same way as the (d)correction". It appears at the bottom of the GHA sub-column for planets. Lets look at problem 2
PROBLEM 2
On the 11 December 1981, your vessel's 1816 ZT DR position is LAT 26°30.0'N, LONG 140-35.0'E, you take a celestial sight of the Venus. The chronometer time of the sight is 9h 14m 52s.
The chronometer error is 01m 02s slow. Compute the GHA, Dec., and LHA of Venus
STEP 1
Using GMT, and Greenwich date of observation, enter the Nautical Almanac and record tabulated hourly value of GHA and TAB DEC. in your form.
BODY Venus
DATE 11 December 1981
LAT 26-30.0N
LONG 140-35.0E
Hs
IE
Hs
DIP
Ha
Alt. Corr.
Ho
ZT 11th 1816
ZD -9
GMT 11th 0916
CT 9h 14m 52s
CE 01m 02s slow
CCT 11th 9h 15m 54s
GHA (Aries) 270-35.6
M&S (Aries) 3-58.5
SHA --------
V (0.8) + 0.2
GHA 274-34.3
DR LONG + 140-35.0E
LHA 55-09.3
TAB DEC S 21-47.4
d corr (0.6) +/- 0.2
DEC S 21-47.2
STEP 2
At the foot of each GHA sub-column for the PLANETS, a number is found. This number is the "v" correction. In this case "v = 0.8." Record this in your form. The "V" correction is always plus (+) for GHA except in the case of the inferior planet Venus, which has an orbit inside the earth's orbit. Its apparent motion westward, as compared with the sun's motion, shows that Venus has a numerically lesser, relative speed. When its correction should be subtracted, the letter "V" will be prefixed by a minus sign. The purpose of the "V correction is to interpolation and to keep tabulated values at a minimum, and makes possible the use of the GHA value for minutes and seconds as tabulated for the sun.
STEP 3
Record the "d" correction for the declination
STEP 4
Turn to the yellow pages of the Nautical 8.lInanac, and find the "15 minute page," enter with "54-seconds." Then under the Sun and Planets column find the increase in the Venus' GHA since the last tabulated (hourly) value, 3" 58.5.' is your M&S corre,ction and enter this in your form.
While on the 15-minute page under the "v" or"d" correction column, find the "v" 0.8 on the left hand side. This is equal to 0.2', enter this in your form and in this case it is added. At the same time, find your "d" 0 .. 6 :: 0.2. enter this in your format. This will be the declination (dec) of the Venus at the time of sight.
STEP 5
Add the GHA, M&S, and "v" correction to get the GHA TOTAL; subtract the "d" correction to find the declination of Venus
STEP 6
Bring down your DR longitude and enter it in
your form. The rule is:
LHA = GHA + EAST LONGITUDE LHA = GHA - WEST LONGITUDE So, we ADD our DR longitude to get the LHA of Venus
