USCG USCG NAV
Set 5 • Question #136 of 247
Launch Interactive Practice Room On 2 January you observe the lower limb of the Sun at a sextant altitude (hs) of 35°50.4'. The index error is 0.8' on the arc. The height of eye is 24 feet (7.3 meters). What is the observed altitude (Ho)?
A
35°50.3'
B
35°54.7'
C
35°59.7'
✓ Correct Answer
D
36°05.6'
USCG NMC Regulatory Explanation
Index error occurs when the sextant index mirror and horizon glass are not parallel at 0° 00.0'. 'On the arc' errors are subtracted; 'off the arc' errors are added to sextant altitude readings.
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