Hover or tap underlined Spanish terms to see their translation and exam tip.
El día 25 de noviembre de 2023, poco después de cruzar el Trópico de Cáncer navegamos con Rumbo verdadero Rv= 340°. A la hora de la meridiana se observa la altura instrumental del Sol (limbo inferior) Ai= 43°17,7´, siendo la declinación δ= (-)20°40,1´. La elevación del observador es de 3 metros y el error de índice del sextante es Ei= (-)4´. Se pide determinar la latitud observada en la que nos encontramos en dicho momento.On 25 November 2023, shortly after crossing the Tropic of Cancer on Rv = 340°, at meridian transit the Sun's lower-limb sextant altitude is Ai = 43° 17.7', declination δ = −20° 40.1', height of eye 3 m, and index error Ei = −4'. Find the observed latitude.
Show the answer
Correct answer: b) l = 25° 54.0' N.
Why it is correct
Correcting Ai = 43º 17.7′ with Ei = −4.0′, dip for 3 m (−3.1′), and November lower-limb Sun correction (+15.3′) gives true altitude av = 43º 25.9′ and zenith distance z = 90º − av = 46º 34.1′ N. With d = 20º 40.1′ S, l = 46º 34.1′ − 20º 40.1′ = 25º 54.0′ N.
Why the others are not
- a) Miscalculates the zenith distance or applies the semi-diameter with the wrong sign.
- c) Forgets to subtract dip of the horizon or index error.
- d) Omits the Sun's semi-diameter and refraction correction.
How to work it out in the exam
- At meridian transit, l = z + d (with signs: north z and south declination subtract).
Where this question comes from
- Ministerio de Transportes (Madrid) · 2023 · Convocatoria de noviembre · CY Test 1 · question 18 Official paper · Official answer key
- Ministerio de Transportes (Madrid) · 2023 · Convocatoria de noviembre · CY Test 2 · question 11 Official paper · Official answer key
Pending instructor review. Machine translation, not reviewed.