Meridian Transit of the Sun Homework Q

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Meridian Transit of the Sun
Homework Q A
Junior Navigation Chapter 9
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• Objectives
• Determine the zone time of meridian transit of
  the sun by the GHA Method.
• Make a meridian-transit observation of the sun
  and compute latitude from the observation

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Practical Exercise Problem 1. Follow the
Student Manual for guidance
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• 2. When the sun crosses your meridian its
  azimuth is
• 90 or 270
• 45 or 225
• 180 or 360
• 60 or 240

Ref. 4
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3. When the sun crosses your meridian its LHA
is a. 0 b. 90 c. 180 d. 270
Ref. 4
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4. An advantage of using a meridian transit
sight to obtain latitude is that this method
requires a. use of a calculator. b. use of
tables. c. plotting. d. the maximum altitude of
the sun.
Ref. 4, 15, 17
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5. The mean sun a. usually agrees with the
apparent sun. b. never agrees with the apparent
sun. c. moves in an erratic motion. d. moves
in a constant motion.
Ref. 7
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6. GHA of the Sun a. defines the position of
the hour circle of the mean sun. b. defines the
position of the hour circle of the apparent
sun. c. can be converted to mean time by
dividing by 15 per hour. d. is measured from
the lower branch of the Greenwich meridian to
the apparent sun.
Ref. 9
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• 7. Find the ZT of meridian transit for the
  following dates and Longitudes
• Lo 175 46' W on March 29 __________
• b. Lo 116 40' E on June 23 __________
• c. Lo 147 21' W on August 16 __________
• d. Lo 128 36' E on December 5 __________

ZT 11-47-41 ZT 12-15-26 ZT 11-53-30 ZT
12-16-11
Ref. 10 - 11
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8. The sun's declination on June 21 is
approximately a. 16.7 S b. 23.4 S c.
16.7 N d. 23.4 N
Ref. 16, Fig. 9-2
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9. You observe the sun at its maximum altitude,
south of your position, and determine Ho is 65
32', and declination is 20 10' S. What is your
latitude? _______ Solution Observer is North
of Sun Ho 6532'Co-Alt 90 - Ho
2428'Co-Alt 2428'N Dec 20 10'S
(Co-Alt Dec opposite names,
subtract) Lat 0418'N
4 18'N
Ref. 18
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10. On May 7 you observe the sun at its maximum
altitude, north of your position, and determine
Ho is 62 41' at a corrected UT time of 21 - 56
- 07. What is your latitude? ________
1016.9'S Solution
Observer is South of SunAlmanac Excerpt (App.
B) for 7 May 21 hr Dec 1701.4'N d()
0.7 dcorr 0.7' Dec
1702.1'NHo 6241'Co-Alt 90 - Ho 90 -
6241'Co-Alt 2719.0'S (since observer south
of sun)Dec 1702.1'N (Co-Alt Dec opposite
names, subtract) Lat 1016.9'S
Ref. 18
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11. On April 18 you are at approximately L 35N
and Lo 17E. You take a series of sights on the
lower limb of the sun around the time of LAN.
Your HE is 10' and the sextant IC is 0.4'. a.
What is your best estimate of the time of LAN?
__________ b. What is your Lat?   ____________
11-50-38 Lat 35 04.5'
Sight No. ZT hs 
  1 11-34-57 65 24.4'    2 11-38-12 65
27.9'    3 11-40-05 65 31.3'   
4 11-42-50 65 36.3'    5 11-46-36 65 38.0' 
  6 11-48-02 65 39.1'    7 11-49-10 65
39.4'    8 11-50-38 65 39.5'
9 11-51-24 65 39.2'    10 11-52-18 65 39.0' 
  11 11-54-16 65 38.9'    12 12-00-41 65
33.9'    13 12-03-35 65 29.5'   
14 12-05-40 65 24.3' 
Click to view solution on MT Form
Click to view plot of hs vs. ZT
Ref. 18 -21
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Meridian Transit of the Sun
End Of Homework Q A
Junior Navigation Chapter 9