On 29 June you observe the star Achernar at a sextant altitude (Hs) of 54°18.9'. The index error is 4.7' off the arc. The height of eye is 58 feet. What is the observed altitude (Ho)?

Question

On 29 June you observe the star Achernar at a sextant altitude (Hs) of 54&deg;18.9'. The index error is 4.7' off the arc. The height of eye is 58 feet. What is the observed altitude (Ho)?

Accepted Answer

Option B: 54&deg;15.5'. Per Bowditch celestial reduction procedures, index error 'off the arc' is added to sextant altitude. Subtracting the dip correction for a 58-foot height of eye and applying star/planet refraction results in an observed altitude (Ho) of 54&deg;15.5'.

On 29 June you observe the star Achernar at a sextant altitude (Hs) of 54&deg;18.9'. The index error is 4.7' off the arc. The height of eye is 58 feet. What is the observed altitude (Ho)?

On 29 June you observe the star Achernar at a sextant altitude (Hs) of 54°18.9'. The index error is 4.7' off the arc. The height of eye is 58 feet. What is the observed altitude (Ho)?