12 



UNITED STATES COAST GUARD 



20. NAUTICAL ASTRONOMY AND NAVIGATION DEFINITIONS. 



What is: 



1. Parallax? 



2. Computed altitude? 



3. The mean sun? 



4. Refraction? 



5. A time zone? 



6. A meridian? 



7. A great circle? 



8. The equation of time? 



9. Greenwich hour angle? 



10. Local hour angle? 



11. Dead reckoning? 



12. Observed altitude? 



13. The Zenith? 



14. Meridian angle? 



15. Magnetic variation? 



16. Local mean time? 



17. A knot? 



18. A planet? 



19. An assumed position? 



20. The date line? 



21. An Azimuth? 

 82. Apparent noon? 



23. A line of position? 



24. The cotangent of an angle? 



25. Dip? 



26. Local apparent time? 



27. 

 28. 

 29. 

 30. 

 31. 

 32. 

 33. 

 34. 

 35. 

 36. 



37. 

 38. 



39. 

 40. 

 41. 

 42. 

 43. 

 44. 

 45. 

 46. 

 47. 

 48. 



The secant of an angle? 

 The cosine of an angle? 

 The tangent of an angle? 

 Mean time? 

 A fix? 



The sine of an angle? 

 Interpolation? 

 A meridian transit? 

 Relative bearing? 

 The meaning of the term "de- 

 parture" as used in the sailings? 

 The cosecant of an angle? 

 Semi-diameter of a celestial 

 body? Draw a sketch to illus- 

 trate. 



An intercept? 

 Zenith distance? 

 Declination? 

 A celestial meridian? 

 A reciprocal bearing? 

 A vertical circle? 

 The elevated pole? 

 The celestial horizon? 

 The supplement of an angle? 

 Magnetic deviation? State its 

 cause. 



22. SIGNALING BY INTERNATIONAL CODE FLAGS, 

 FLASHING LIGHT; 

 LIFESAVING, STORM AND SPECIAL SIGNALS. 



How would you indicate in signalling 

 by blinker light that you were going 

 to send a message in code? 



In receiving a message by blinker you 

 miss all but the last two words "in dis- 

 tress." How would you request the 

 transmitter to repeat that part of the 

 message which you missed? 



What is the procedure sign for "Mes- 

 sage received"? 



Draw all the symbols of the Morse 

 code. 



In the Morse code, what does the let- 

 ter "G" signify when signalling by 

 blinker? 



In exchanging messages by means of 

 flashing light, is it always necessary for 

 vessels to establish their identity? 



Under what circumstances can ves- 

 sels signalling by flashing light omit 

 both call and identity components of the 

 message? 



w w w w 



What does • — sig- 

 nify during a communication when sent 



by blinker'' 



What is the general call employed in 

 signalling by means of flashing light? 



If you missed part of a message 

 being sent by blinker light, how would 

 you send "Repeat all after"? 



What is the procedure sign for "you 

 are correct"? 



In signalling by blinker light, how 

 would you signal: "Erase entire mes- 

 sage"? 



What is the procedure for the space 

 sign? 



Write the entire procedure of a plain 

 language message in Morse Code, leav- 

 ing out any text. 



What code message would you send 

 to a pilot station with the ship's signal 

 searchlight to indicate "I desire a 

 pilot"? 



How does a receiving ship acknowl- 

 edge code groups and numbers in sig- 

 nalling by blinker light? 



What is the procedure sign for 

 "from" in blinker signalling? 



