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Nos encontramos en situación 43° 30′ S, 89° 24′ E. Sabiendo que la declinación del Sol es 18° 00′ S, calcular el acimut del Sol en el instante del orto verdadero.In position 43° 30′ S, 89° 24′ E, given that the Sun's declination is 18° 00′ S, calculate the Sun's azimuth at true sunrise.
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Correct answer: c) 115°
Why it is correct
At true sunrise, sin A = sin d / cos l = sin(18º) / cos(43º 30′) = 0.42598, giving an amplitude of E 25.2º S since declination is south. In circular notation, the sunrise azimuth is 90º + 25.2º = 115.2º ≈ 115º.
Why the others are not
- a) Subtracts 27º from 90º as if declination were north and with an inaccurate angle.
- b) Takes 90º − 25º = 065º (E 25º N), which would correspond to north declination.
- d) Overestimates the amplitude by 3º.
How to work it out in the exam
- Sunrise with south declination: azimuth lies between East (090º) and South (180º) → 90º + A.
Where this question comes from
- Junta de Andalucía · 2022 · 3ª convocatoria · CY Módulo de navegación · question 15 Official paper · Official answer key
Pending instructor review. Machine translation, not reviewed.