You observe the star Deneb at a sextant altitude (hs) of 48°34.8' on 16 December. The index error is 4.0' off the arc. The height of eye is 58 feet. What is the observed altitude (Ho)?

Correct Answer: Option A — 48°30.5'

Apply index error (off = subtract) to the sextant altitude. Subtract the dip correction for a 58-foot height of eye. Apply the refraction correction for stars from the Nautical Almanac. The resulting observed altitude (Ho) is 48°30.5', following standard Bowditch celestial navigation reduction procedures for stellar observations.