Amplitude Sun (Celestial Horizon)
When computing an amplitude problem, you are to assume that a celestial body is on the celestial horizon when the stem of the question indicates that the body is on the "CELESTIAL HORIZON" or is at any elevation above the horizon, 1/2 to 2/3rds of a diameter or 21' of arc above the "VISIBLE HORIZON". Do not apply the Table 28, Correction of Amplitude as Observed on the Visible Horizon to the observed bearing. If the stem of an amplitude of the sun problem does not provide the zone time of observation (ZT) assume that sunrise is at 0600 ZT and sunset is at 1800 ZT in order to establish the correct chronometer time and or GMT / Date before entering the Nautical Almanac to compute the Sun's declination for the time of the observation.
1. On 8 December 1981, in DR position Lat. 21° 56.1' S, Long. 17° 21.6' E you observe an amplitude of the Sun. The Sun's center is on the celestial horizon and bears 240.5° psc. The chronometer reads 05h 27m 21s and is 00m 47s fast. Variation in the area is 3.3° E. What is the deviation of the standard magnetic compass?
A. 1.5°W
B. 0.3°W
C. 0.6° E
D. 1.5° E
2. On 11 January 1981, your vessel's 0655 zone time DR position is Lat. 24° 30.0' N, Long. 122° 02.0' W, when an amplitude of the Sun is observed. The Sun's center is on the celestial horizon and bears 101.0° per standard compass. Variation in the area is 11.6° E. The chronometer reads 02h 52m 48s and is 02m 12s slow. What is the deviation of the standard compass?
A. 1.4° E
B. 1.4° W
C. 4.6° E
D. 4.6° W
3. On 10 February 1981 in DR position Lat. 25° 32.0' N, Long. 135° 15.0' E, you observe an amplitude of the Sun. The Sun's center is on the celestial horizon and bears 109° psc. The chronometer reads 09h 43m 25s and is 03m 20s fast. Variation in the area is 4.5° W. What the deviation of the standard magnetic compass?
A. 1.6° E
B. 2.9° W
C. 10.5° E
D. 10.5° W
4. On 9 May 1981, your vessel's 1809 ZT DR position is Lat. 48° 13.7' N, Long. 168° 36.3' E, when an amplitude of the Sun is observed. The Sun's center is on the celestial horizon and bears 283.7° per standard compass. Variation in the area is 13.0° E. The chronometer reads 07h 13m 19s and is 02m 56s fast. What is the deviation of the standard compass?
A. 0.1° W
B. 1.1° W
C. 1.1° E
D. 1.9° W
Amplitude of the Sun (Visible Horizon)
A correction must be applied whenever the amplitude of a celestial body is observed on the "VISIBLE HORIZON". NEVER apply the Table 28, Correction of Amplitude as Observed on the Visible Horizon correction unless the stem of an amplitude problem specifically indicates that the center of a celestial body is on the "VISIBLE HORIZON". NEVER apply the Table 28, Correction of Amplitude as Observed on the Visible Horizon correction to the computed bearing or amplitude. The Table 28, Correction of Amplitude as Observed on the Visible Horizon correction should be applied to the observed bearing of a celestial body on the "VISIBLE HORIZON". For the sun, a planet, or a star, apply the correction to the observed bearing in the direction away from the elevated pole. For the moon apply half of the correction toward the elevated pole.
5. On Sunday, 8 November 1981, your ship is enroute from Texas City, TX, to Portland, ME. At 0632 ZT, you fix your position by Loran at Lat. 27° 06.0' N, Long. 90° 36.0' W. When the lower limb of the Sun was two-thirds of a diameter above the visible horizon, the Sun bore 105° per standard magnetic compass. At this time the chronometer read 12h 39m 20s and is 3m 20s slow. If the variation is 3° E, determine the deviation of the standard compass?
A. 0.8° E
B. 0.8 W
C. 3.8° E
D. 3.8° W
6. On 15 July 1981, in DR position Lat. 22° 19.0' N, Long. 154° 37.0' W, you observe an amplitude of the Sun. The Sun's center is on the visible horizon and bears 298° psc. The chronometer reads 04h 45m 19s and is 01m 56s slow. Variation in the area is 7.5° W. What is the deviation of the standard magnetic compass?
A. 2.7° W
B. 3.0° E
C. 3.6° W
D. 3.9° E
7. On 23 August 1981, at 0604 ZT, in DR position Lat. 16° 42.3' S, Long. 28° 19.3' W, you observed an amplitude of the Sun. The lower limb was a little above the horizon, and the Sun bore 076.0° pgc. At the time of the observation, the helmsman reported that he was heading 143° pgc and 167° per magnetic compass. The variation in the area was 23° W. What were the gyro error and deviation for that heading?
A. 1° W GE / 2° W DEV
B. 1° E GE / 1° E DEV
C. 2° W GE / 1° E DEV
D. 2° E GE / 1° E DEV
8. On 20 June 1981, your vessel's 1955 ZT DR position is Lat. 52° 38.9' N, Long. 03° 42.7' E, when an amplitude of the Sun is observed. The Sun's center is on the visible horizon and bear 311° per gyrocompass. Variation in the area is 6° W. At the time of the observation, the helmsman noted that he was heading 352° per gyrocompass and 358° per steering compass. What is the gyro error and deviation for that heading?
A. 1.3° W GE / 1.3° E DEV
B. 0.0° GE / 0.0° DEV
C. 1.3° W GE / 1.3° W DEV
D.1.3° E GE / 1.3° E DEV
