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REFERENCE NO: D31 - NAV 3
1. COURSE NAME: Celestial Navigation 1
2. COURSE DESCRIPTIONS: The course includes the solar systems, celestial
sphere and equinoctial system of coordinates, hour angle, daily
motion and horizontal system of coordinates, sextant and altitude
corrections, amplitude, time and equation of time, nautical of
almanac and merdian observations.
3. NUMBER OF UNITS FOR LECTURE AND LABORATORY:
3 LECTURE, 1 LABORATORY = 4 UNITS
4. NUMBER OF CONTACT HOURS:
3 LECTURES, 3 LABORATORY = 6 HOURS
5. PREREQUISITE: College Algebra, Plane & Spherical Trigonometry, NAV 2 Terrestrial Navigation 2
6. COURSE OBJECTIVES: The student shall be able to find the time when the
sun, the planets and selected stars pass the meridian and establish
the latitude of the ship by celestial observations.
FUNCTION:
F1 – Navigation at the Operational Level (STCW Code Table
A-II/1)
7. COURSE OUTLINE:
LEARNING OBJECTIVES / OUTCOMES:
The students shall be able to . . . . . .
7.1 Solar systems
7.1.1 describe the motions of bodies in the solar system;
7.1.2 describe the earth's elliptical orbit, and state approximate
perihelion and aphelion distances and dates;
7.1.3 explain the eccentricity of the earth's orbit;
7.1.4 describe the inclination of the earth's axis to the plane of the
orbit and the stability of the axis (ignoring precession) and show
how it causes the seasons;
7.1.5 state the dates of the solstices and equinoxes;
7.1.6 explain the concept of the earth's axial rotation causing day and
night;
7.1.7 explain what causes the varying length of daylight through the
year;
D31- NAV 3
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7.1.8 describe daylight and darkness conditions in various latitudes at
the solstices and equinoxes;
7.1.9 state the significance of the tropics of Cancer and Capricorn and
the Arctic and Antarctic Circles;
7.1.10 identify planets and at least 10 stars to be used for navigational
purposes.
7.2 Celestial sphere and equinoctial system of coordinates
7.2.1 define celestial sphere;
7.2.2 explain the apparent annual motion of the sun and the concept
of the ecliptic;
7.2.3 define celestial poles, celestial meridians, equinoctial and the
obliquity of the ecliptic;
7.2.4 explain the purpose of using the equinoctial as a fixed reference
plane and the direction of the First Point of Aries as a reference
direction (ignoring the effect of precession);
7.2.5 describe the equinoctial system of co-ordinates and define
sidereal hour angle, declination and polar distance;
7.2.6 extract information from the star diagrams in the Nautical
Almanac.
7.3 Hour angle
7.3.1 describe the concept of the earth's axial rotation causing change
in the hour angle of bodies;
7.3.2 define Greenwhich Hour Angle (GHA), Local Hour Angle (LHA)
and longitude and explain their relationships;
7.3.3 state the rate of change of GHA of the sun and Aries;
7.3.4 estimate the geographical position of a body for any given GMT.
7.4 Daily motion and horizontal system of coordinates
7.4.1
7.4.2
7.4.3
7.4.4
7.4.5
7.4.6
7.4.7
7.4.8
7.4.9
D31- NAV 3
define rational horizon, zenith and nadir;
define vertical circle and prime vertical circle;
define elevated pole and depressed pole;
prove that altitude of the elevated pole is equal to the observer's
latitude;
define the observer's upper and lower celestial meridian;
trace the apparent daily path of all bodies;
define true altitude, azimuth and true zenith distance;
discuss rising and setting points and define amplitude;
explain the meaning of the term circumpolar and describe the
conditions necessary for a body to be circumpolar;
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7.4.10 describe the condition necessary for a body to cross the prime
vertical;
7.4.11 draw figures on the plane of the rational horizon and of the
observer's celestial meridian, using the equidistant projection
to illustrate navigational problems and principles;
7.4.12 draw a horizon system of coordinates showing zenith, nadir,
north/south horizon, declination, and altitude and observers
latitude.
7.5 Sextant and altitude corrections
7.5.1
7.5.2
7.5.3
7.5.4
7.5.5
7.5.6
7.5.7
7.5.8
7.5.9
7.5.10
7.5.11
7.5.12
7.5.13
define sextant altitude;
demonstrate ability to read the angle of the sextant;
demonstrate ability to correct a sextant with one or more errors
of perpendicularity, side error or index error;
demonstrate how to find and correct the index error of the
sextant by using the horizon;
use the sextant for taking vertical and horizontal angles;
explain the purpose of altitude correction;
define visible, sensible and rational horizons and explain their
practical applications;
define observed altitude and true altitude;
apply the corrections for dip, refraction, semi-diameter and
parallax and explain their causes;
apply index error;
illustrate the effect of terrestrial refraction on the dip and
distance of the sea horizon;
use the altitude correction tables in the Nautical Almanac,
including reference to critical tables, interpolation tables and
low-altitude correction tables;
obtain the true zenith distance from the true altitude of the
body.
7.6 Amplitude
7.6.1
7.6.2
7.6.3
D31- NAV 3
determine the observed altitude of the sun when the true
altitude is zero;
explain the effect of latitude on the accuracy of amplitude
observations;
calculate the latitude and local mean time (LMT) of the
theoretical and visible rising and setting of the sun.
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7.7 Time and equation of time
7.7.1
7.7.2
7.7.3
7.7.4
7.7.5
7.7.6
7.7.7
7.7.8
7.7.9
define the apparent solar day and state the relationship
between local hour angle (LHA) of the sun and the latitude;
define the sidereal day and explain why it is a fixed time
interval;
explain the reasons for the sun's irregular rate of change of
sidereal hour angle (SHA) and hence the necessity to adopt
the astronomical mean sun for timekeeping purposes;
define the equation of time (ET) and its components;
determine the ET from the Almanac and its sign of application;
define GMT, LMT and longitude;
define zone times and standard times;
calculate the ship's time when a celestial body will pass the
meridian and the ship is sailing in an easterly or westerly
direction;
use time signals to find the correct time of a watch.
7.8 Nautical almanac
7.8.1
7.8.2
7.8.3
7.8.4
7.8.5
7.8.6
7.8.7
7.8.8
7.8.9
demonstrate ability to find relevant information contained in the
Nautical Almanac;
use correctly the tables of corrections and incremental
corrections in the Nautical Almanac;
find the LHA of a body, given the date, GMT and longitude of
the observer;
explain the use of the First Point of Aries;
find the LHA of Aries, given the date, GMT and longitude of the
observer;
explain what is meant by the sidereal hour angle (SHA) of a
star and obtain it from the Nautical Almanac;
derive the LHA of a star from the LHA of Aries and the SHA of
the star;
extract information from the tabulation of the rising and setting
of the sun in the Nautical Almanac;
use the Nautical Almanac to obtain the local mean time (LMT)
of the meridian passage of a body to the nearest minute.
7.9 Meridian observations
7.9.1
7.9.2
D31- NAV 3
find the ship’s time when a celestial body will pass the
meridian the next day when the ship is sailing at a constant
speed on an easterly or westerly course;
establish the appropriate time for observing planets and stars
in the meridian on a given day in a given position;
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7.9.3
7.9.4
establish the latitude of the ship by observing celestial bodies
in the meridian;
identify at least 10 stars and planets use as reference for
navigation.
8. EQUIPMENT, MATERIALS, CHEMICALS, TEACHING AIDS:
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
protractor;
parallel ruler/nautical triangle;
dividers;
electronic calculator with trigonometric functions;
Nautical tables (e.g. HO publications or useful tables);
Nautical Almanac;
Position plotting celestial sheets
Sextants (at least 2 units)
Star charts/star finder;
9. REFERENCES:
9.1 Bowditch. American Practical Navigation, Vol. 1 & 11, 1997
Edition.
9.2 Maloney, Elbert. Naval Institute Press. Navigation and Piloting.
9.3 Frost. Practical Navigation for Second Mates, 6th Edition. 1985.
ISBN 0-85174-397-8.
9.4 Frost. The Principles and Practice of Navigation. 1983. ISBN 085174-444-3.
9.5 IMO Model Course 7.03, 1999 Edition. ISBN 92-801-6105-9.
9.6 Ynion, Eugenio J. Celestial Navigation I.
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