Hover or tap underlined Spanish terms to see their translation and exam tip.
Para un observador en latitud N, cuando el acimut de un astro del hemisferio norte es 180º:For an observer in North latitude, when the azimuth of a northern-hemisphere celestial body is 180º:
Show the answer
Correct answer: c) The body’s vertical circle, the body’s hour circle and the observer’s meridian all lie on the same great circle.
Why it is correct
When a body’s azimuth is 180° (or 000°), the body is transiting the observer’s meridian. At that instant its vertical circle and its hour circle lie in the plane of the observer’s meridian. (For a northern body with δ < φ bearing 180° at upper transit, altitude is at its maximum, not minimum.)
Why the others are not
- a) A body on the upper meridian with declination of the same name as latitude is culminating high above the horizon.
- b) At Z = 180° that body is on the upper meridian at its maximum altitude.
- d) Option b) is false because altitude is maximum at upper transit.
How to work it out in the exam
- At meridian transit (Z = 000° or 180°): vertical circle, hour circle and observer’s meridian coincide.
Where this question comes from
- Junta de Andalucía · 2016 · 1ª convocatoria · CY Módulo de navegación · question 4 Official paper · Official answer key
Pending instructor review. Machine translation, not reviewed.