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GATE 2023 CE (CE1) – Question 22

Geomatics Engineering · Distance and angle measurement, levelling, traversing, triangulation, total station · 1 mark · Multiple choice

The direct and reversed zenith angles observed by a theodolite are 56° 00' 00" and 303° 00' 00", respectively. What is the vertical collimation correction?

  1. +1° 00' 00"
  2. −1° 00' 00"
  3. −0° 30' 00"
  4. +0° 30' 00"

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Correct answer: (D) +0° 30' 00"

Explanation

The sum of the face-left and face-right zenith angles should be 360°. Here the sum is $56° + 303° = 359°$, which is 1° short, so each reading needs the correction of half of the difference: $\frac{360° - 359°}{2} = +0° 30' 00''$.