11

The SextantThe Sextant

QuizQ & AJunior NavigationJunior Navigation

Chapter 2Chapter 2

22

1. When reading sextant altitude, in what order are degrees, minutes, and tenths of minutes read?

Degrees

Minutes

Tenth of Minutes

1st

2nd

3rd

33

2. When timing sights, in what order are hours, minutes, and seconds read from the watch?

Seconds

Minutes

Hours

1st

2nd

3rd

44

3. Before taking sights on the Sun, you sight the horizon and align the direct and reflected images of the horizon. Your Sextant reading is 1.8' on the arc.

a.What is the IE?

b. What is the IC?

+1.8'

-1.8'

55

4. Before taking sights on the Sun, you sight the horizon and align the direct and reflected images of the horizon. Your Sextant reading is 58.2' off the arc.

a.What is the IE?

b. What is the IC?

-1.8'

+1.8'

66

5. You need to use the shade glasses on the sextant when taking sights on the sun.

a. True

b. False

77

6. You take a run of sights on the Sun with the following times of sights and sextant altitudes. Which of the sights are probably erroneous?

WT hs17-42-33 27° 01.4' 17-43-12 26° 57.8'17-43-52 26° 58.7' 17-44-27 26° 50.1' 17-44-49 26° 50.0'17-45-17 26° 45.8'

Bad Sight

Bad Sight

Hint: Plot the run of sights [See next slide for plot]

88

hs

26.7

26.75

26.8

26.85

26.9

26.95

27

27.05

42 42.5 43 43.5 44 44.5 45 45.5

hs

Bad Sight

Bad Sight

Plot of hs versus WTPlot of hs versus WT Time

hs

WT

99

7. What is the purpose of "swinging the arc" when taking a sight with a sextant?

a. To help obtain a clear view of the horizon.

b. To be sure that the sextant is horizontal at the time of the sight.

c. To help focus the body in the sextant telescope.

d. To be sure that the sextant is vertical at the time of the sight.

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Chapter 2Chapter 2