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Determine la altura verdadera del astro Vega. Altura instrumental = 40º 20'; Ci= -4' y elevación del observador= 5 m.Determine the true altitude of the star Vega given sextant altitude = 40º 20', Ci = -4', and height of eye = 5 m.
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Correct answer: b) 40º 10.8'
Why it is correct
Starting from ai = 40º 20.0′, subtract Ci = −4.0′ (ao = 40º 16.0′), dip for 5 m (−4.0′ → aap = 40º 12.0′), and stellar refraction at 40º (−1.2′), giving av = 40º 10.8′.
Why the others are not
- a) Adds the corrections or applies the Sun's semi-diameter to a star.
- c) Subtracts less dip than the 4.0′ required for 5 m.
- d) Forgets to subtract both index correction and dip.
How to work it out in the exam
- For a star at 40º and 5 m: −4.0′ (Ci) − 4.0′ (dip) − 1.2′ (refraction) = −9.2′.
Where this question comes from
- Ministerio de Transportes (Madrid) · 2021 · Convocatoria de julio · CY Test 2 · question 18 Official paper · Official answer key
- Ministerio de Transportes (Madrid) · 2021 · Convocatoria de julio · CY Test 3 · question 20 Official paper · Official answer key
Pending instructor review. Machine translation, not reviewed.