In modern epoch the Global Navigations Satellite Systems widely cover the navigation needs: terrestrial, aerial and maritime as well.
The celestial navigation seems to be obsolete, but although the newest radio navigation systems replace the older ones, the nautical astronomy continues to be taught at the maritime officers; in according to STCW convention in the latest amended version of Manila 2010.
The aim of the course is to provide the theoretical and practical aspects for the determination of the astronomical position at sea. Specifically, the student shall demonstrate to known and to understand the fundamental issues: to estimate the position at sea and to control the error’s compass using celestial bodies. Analytical and graphical approaches can be employed to tackle such challenge, as well as the correct use of technical publication (in English language as well).
The student shall understand the operating principle of the instruments employed to obtain astronomical coordinates; such as sextant, he shall know the measuring and adjustment procedures for such instrument.
The student shall be able to know how to independently evaluate situations different from the standard presented by the teacher during the course and to adopt the best resolution methods.
Finally, the student shall have the ability to present a dissertation about Astronomical Navigation topics using the correct scientific language.
It is necessary to acquire the competences provided by the Mathematical Analysis, Physics, Geodesy and Navigation (or Fundament of Navigation) courses.
-Celestial sphere and its coordinate systems: locals, equatorial and ecliptic.
-Principal formulas of spherical trigonometry applied to the transformation of the celestial coordinates.
-Daily apparent motion of the celestial sphere; Kleperian motion, phenomena that alter the equatorial coordinates of the stars.
- The time, how to measure it; sidereal time, true time, mean time of the celestial bodies. Time passage, astronomical time and atomic one. The marine chronometer and its errors.
The nautical almanac, instruction to use.
-The use of azimut of the stars for determination of the deviation of the magnetic and gyroscopic compass
-The marine sextant, measures and adjustments of a sight. Measurement errors and their modeling.
-Polaris start to determine the observer latitude.
-LOP(Line Of Position) related to astronomical sight measurements; its representation on nautical charts.
-Linearization of the altitude circumference;
-Saint Hilaire: static LOP and running LOP.
-LOP and related errors, practical employment of single astronomical LOP.
-Estimation of position with astronomical observations (sight reduction), using two LOP, introduction to bisector track. Estimation with three and four astronomic LOP in running. Error analysis on the running fix.
- Graphical methods employed on the Mercator chart.
- Introduction to analytical methods.
- Optimizing the position by means of the least square method.
- Using the Star Finder to simulate twilight observations.
The course deals with the basic elements required for the use of celestial bodies to determine: the ship's position, design of star observation (sight) at twilight and control of position at noon.
The course furnishes some competencies required by the STCW Convention, as amended, for Deck Officers and Marine Engineers at Operational Level, embodied in the MIT decree dated 19th December 2016, namely “Percorso formativo per accedere alle figure professionali di Allievo Ufficiale di Coperta e Allievo Ufficiale di Macchina”.
Particularly, the course provides the competencies, listed in the Attachment I of the above-mentioned decree, for Deck Officer Cadets: Ability to use celestial bodies to determine the ship’s position.
Further details about the acquired competencies are reported in the section objectives.
Flora, Ferdinando. Astronomia nautica (Navigazione astronomica). HOEPLI EDITORE, 1987.
Istituto Idrografico della Marina, Effemeridi Nautiche 2020 (I.I. 3132), IIM, 2019.
DUTTON, Benjamin; CUTLER, Thomas J. Dutton's Nautical Navigation. Naval Institute Press, 2004.
Slide used during the course in PDF format.
The exam goal is to check the level of achievement of the above-mentioned training objectives.
The exam is divided into 2 parts that may take place on the same day.
1) A written test consists to solve an exercise where astronomical measurements are used to estimate a geographic position of a ship.
2) an oral test in which the ability to link and compare different aspects of the course will be evaluated.
The student having a score less than 18 at written test, will not be admitted to the oral test.
Lectures are in Italian. The professor is fluent in English and is available to interact with students in English, also during the examination.