Example 4 Planet
During evening twilight on 28 December 1981, the sextant altitude (Hs) of the planet Venus was 29°43.2'. The height of eye was 40 feet, and the index error was 2.0' on the arc. What was the observed altitude (Ho)?
BODY Venus
DATE 28 December 1981
DR LAT ---------
DR lONG ---------
Hs 29°43.2'
IE - 2.0' on
Hs 29° 41.2'
Dip (40 ft) - 6.1'
Ha 29° 35.1'
ALT CORR - 1.0'
Ho 29° 34.1
STEP 1
Record the given information in your format.
STEP 2
Apply your IE, in this case it is on the arc, so we subtract it.
STEP 3
Using the DIP Table on the inside cover of the Nautical Almanac, enter with your height of eye 40 feet = - 6.1'. Dip correction is always a minus correction
STEP 4
On page A2 "Altitude Correction Tables 100 - 900 Sun, Stars, Planets" under the STARS AND PLANETS section. Enter with your Ha and find the Al T Correction [ -1.7' ]. Venus & Mars have an additional correction. Under Venus on December 28 with an Ha of 290 = + 0.7'. You take net result and use that as your Al T corr. Main corr - 1.7 Additional Corr. + 0.7 Net Corr. - 1.0
