🔍 Key Concepts

• Latitude by celestial observation (how altitude of a body relates to observer’s latitude) • Meaning of lower transit vs. upper transit (meridian passage) • What observing a body on the prime vertical or celestial horizon tells you

💭 Think About

• Ask yourself: In which case does the observed altitude of a celestial body most directly give you information about your latitude? • Which of these positions (horizon, lower transit, Greenwich meridian, prime vertical) is related to the body crossing your local meridian? • When might a navigator time a sun sight so that the computation of latitude is as simple and direct as possible?

✅ Before You Answer

• Be clear on what meridian passage (transit) means in celestial navigation. • Recall the special case where the altitude of a body plus its declination can be combined very simply to obtain latitude. • Verify which of the listed positions is primarily used for longitude determination rather than latitude.