OICNW-1-1C

Obtain a celestial fix

Condition

Aboard a ship at sea, given a standard marine sextant, a clear horizon, a clear or partly cloudy sky, and an accurate time, during a single twilight.

Performance requirement

Behavior Standard
The student will: During assessment, the student shall, at a minimum:

Measure the altitude of three stars and accurately record the times of the observation of each star.

  • Determine altitudes within ± 2 minutes of arc, after correction for index error, as compared with the altitude measured by the assessor at the same time;

  • Record an observation time which is within ± 2 seconds of UTC of the time of observation as determined by the assessor.

Plot three lines of position and advance them to a common time.

Plot the resultant position of the star fix within 1.5 nm of the ship's GPS position at the corresponding time, or within 3 nm of the assessor's solution taken during the same time.

Note: This assessment supports KUP OICNW-A1.01, and is assessed in MT-4371 Sea Term IV: Marine Transportation.