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3 Air Observers school Port Pirie S.A
No. 40 Navigators Course: Astro Theory
1. Draw a figure to some convenient scalea) On the plane of the Observers Celestial Horizon  
b) On the plane of the meridian of the Body. ~ Shewing the PZX triangle when the observers position is 30 S. 120 E. The body has a declination of N.2O° and the L.H.A is 045°  
c) Mark in the azimuth and the altitude on figure (a). Give approximate values for each.  
d) In figure a) indicate the prime vertical. What is the definition of the prime vertical.  
e) Name the following parts of the triangle. “Z X” “P X”.  
f) Define the position circle and shew it on the figures. 
2. Illustrate with diagrams
a) Parallax in Altitude.  
b) Dip  
c) Refraction  
d) The various types of horizons 
3. Shew by means of a diagram, at what times Q correction is minus and plus and when it has a zero and maximum value.
4. An aircraft has T.A.S of 300 mph and a gyro wander of 6’ per minute. Your D/R position is 12 S You observe a body which bears 312(T ) and your aircraft heading is 012 (T). What is the amount and sign of the correction you must apply to the sextant altitude under these conditions.
5. In the vicinity of 40 S and 110 W on the night Dec 2829th you intend using the Astrograph. What is the setting longitude and the Time Difference which you would use.
6. Give a brief description of the principle of the Astrograph. A description of the mechanism is NOT required.
7. What are the time Z T & G M T of the Moonset and Sunrise on Oct 30th, 1943 in latitude 45 N 90 W.
8. Define:
a) siderial Hour Angle, Altitude of a body, Intercept.  
b) In what three Ways can Celestial Longitude be expressed ? Why does one not vary with change in Observers Terrestrial Longitude  
c) Using a diagram only show that LHAx equals GHA plus SHAx plus E minus W longitude. 
9. Using the planisphere determine 3 stars suitable for a fix on the night of 13th, Sept. 1943. (L.D.) at 0300 hrs LMT. Your position is PT. PIRIE.
10. The latitude and longitude of the centre of the position circle about a certain star at 1800 hrs GT on 3/11/45 is 26 18S 154 25 E. What is the star?
If the radius of the circle in nautical miles is 2701  what is the altitude of the Star?
11. Tabulate the procedure for locating and identifying any particular star by use of the Astro Compass.
PART II
1. You are flying at a height of 5,000’ on track 210 (T) with G/S 120K, Your D/R Position at 1930 hours GMT on 5th, Nov, 1943 is 26 18S 65 43 E: You take the following sights :
19 27 30Z HAML Hs 39 30’  
19 30 30Z ALDEBARAN Hs 40 33’  
19 34 30Z SIRIUS Hs 36 16’ 
Your watch is correct and your sextant has no IE. What is fix at 19 34 30?
Plot on squared paper provided using scale 1" equals 10 mins of longitude.
2. When flying at 1500 ft in DR posn 26 12'N 64 52’W at 23 37 30 Zone time the latitude of POLARTS was 29 36’. What was your latitude?
3. Calculate. but DO NOT PLOT the following ‘sights using chosen position nearest to D/R position.
a) G.G. 12/11/43. G.M.T. O1 27 56 D/R 38 37S 16 48’W MOON Hs 36° 054’ 

b) L.D. 14/12/43 Z.T )4 )7 51 D/R 29 24 N 129 27’E MARS Hs 23° 

c) G.D 4/11/43 G.M.T 06 33 28 D/R 34 07S 043 03’W ALPHARD Hs 42°39’ 
4. Establish your latitude from the following sight
L.D. 14/9/43 ZT 00 52 59 D/R 75 58S 179 45W
BODY ACRUX Hs 49 24’
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