### Self Assessment 1

##### § 01 – 05

Descriptive answers should be as full and detailed as possible. Answers involving calculations must show the full working with each function named as shown in the model examples in the text of these chapters; the final answer to a problem alone IS NOT SUFFICIENT.

5. State the instruments and reference books necessary to practice Astro-navigation, giving a brief description of the purpose and use of each.

6. Draw a diagram to illustrate the conception of the celestial sphere, indicating the Earth, the celestial poles and the celestial equator.

7. Explain why the Sun, stars, and other celestial bodies appear to rise E. of, and set W. of, an observer’s meridian.

8. What is the F.P. of Aries FPA and why is this of such importance in Astro-navigation?

9. What is the difference between a so-called fixed and moving celestial body?

10. Name the moving bodies used in Astro-navigation.

11. Why are celestial meridians sometimes called hour circles?

12. Why are three reference meridians necessary in Astro-navigation as opposed to only one reference meridian for terrestrial navigation?

13. Name each of the celestial meridians used as references in Astro-navigation and define the hour angle derived from each.

14. Draw a single diagram to illustrate the L.H.A., G.H.A., S.H.A., and Dec. of a star, naming all the relevant parts.

15. What is the difference between the equinoctial and horizon systems of stating the position of a celestial body

16. Draw a single diagram to illustrate True. Alt., zenith distance, and azimuth of a celestial body, naming all the relevant parts.

17. What is an ephemeris and describe the ephemeredes on the daily pages of the N.A..

18. Using the Astro-navigation Pamphlet extracts from the N.A., calculate the L.H.A. and Dec. of:

a. The ʘ Sun at 15h.44m.33s. G.M.T. Jan 03rd 199X in Longitude 025° 34.0 E

b. The ʘ Sun at 12h.47m.50s. G.M.T. Jul 04th 199X in Longitude 007° 19.0’ W

c. The ʘ Sun at 05h.10m.19s. G.M.T. Jan 20th 199X in Longitude 136° 52.0’ E

d. The ʘ Sun at 18h.08m.47s. G.M.T. Jan 22nd 199X in Longitude 176° 44. 5’ W

19. Using the Astro-navigation Pamphlet, find the L.H.A. and Dec. of:

a. Venus ♀at 08h.11m.26s. G.M.T. Jan 01st 199X in Longitude 000° 00.0’

b. The ☾ Moon at 19h.45m.16s. G.M.T. Jan 19th 199X in Longitude 154° 12.0’ E

c. ✴︎ Procyon at 05h.09m.23s. G.M.T. Jul 05th 199X in Longitude 154º 12.0’ E

d. Jupiter♃at 06h.46m.00s. G.M.T. Jan 21st 199X in Longitude 040° 45.0’ W

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