Example 1 Sun Lower Limb
You observe the lower limb of the Sun at a sextant altitude (Hs) of 42°44.0' on 22 June 1981. The index error is 0.8' off the arc. The height of eye is 70 feet (21.3 meters). What is the observed altitude (Ho)?
BODY Sun lower limb
DATE 22 June 1981
DR LAT
DR LONG
Hs 42° 44.0'
IE + 0.8' off
Hs 42° 44.8'
Dip (70 ft) - 8.1'
Ha 42° 36.7'
ALTCORR + 15.0'
Ho 42° 51.7'
STEP 1
Record the given information in your format.
STEP 2
Apply your IE, in this case it is off the arc, so we add it.
STEP3
Using the DIP Table on the inside cover of the Nautical Almanac, enter with your height of eye 70 feet = - 8.1'. Dip correction is always a minus correction.
STEP4
On page A2 "Altitude Correction Tables 1 OQ - 90° Sun, Stars, Planets" under the Sun -- April - September --(because our problem is in June). Enter with your Ha and find the AL T Corr under the Lower Limb column. Lower limb are always + corrections and upper limbs are - corrections.
Example 2 Sun Upper Limb
You observe the upper limb of the Sun at a sextant altitude (Hs) of 22°34.0' on 2 October 1981. The index error is 1.8' on the arc. The height of eye is 30 feet. What is the observed altitude (Ho)?
Body Sun upper limb
DATE 2 October 1981
DR LAT - - - - - - - - - -
DR LONG ---------------
Hs 22° 34.0'
IE - 1.8' on
Hs 22°32.2'
Dip (30 ft) - 5.3'
Ha 22° 26.9'
ALTCORR - 18.3'
Ho 22° 08.6'
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 30 feet = - 5.3'. Dip correction is always a minus correction
STEP 4
On page A2 "Altitude Correction Tables 10° - 90° Sun, Stars, Planets" under the Sun --- October - March --(because our problem is in October). Enter with your Ha and find the ALT Corr under the Upper Limb column. Remember that Lower limb are always + corrections and upper limbs are - corrections.
