Celestial Navigation ICelestial Bodies

(Fixed Stars)

Celestial bodies used in navigation are divided into two general classes, namely: fixed stars and those that belong to the solar system.

Celestial Bodies

Fixed stars are those celestial bodies that are at such an immense distance from the Earth that they appear to remain in fixed position relative to each other and that whatever movement which they may have are practically imperceptible to us.

Fixed Stars

A nautical almanac is a publication describing the positions of a selection of celestial bodies for the purpose of enabling navigators to use celestial navigation to determine the position of their ship while at sea. The Almanac specifies for each whole hour of the year the position on the Earth's surface (in declination and Greenwich hour angle) at which the sun, moon, planets and first point of Aries is directly overhead. The positions of 57 selected stars are specified relative to the first point of Aries.

Nautical Almanac

Brightness of stars are assigned a number starting with the brightest star starting at about -1 magnitude. Dimmer stars are zero or positive numbers. The larger the number means the dimmer the star is. For example, a star -1 magnitude is brighter than a star 0 magnitude. A star 0 magnitude is brighter than a star 1 magnitude. A star 1 magnitude is brighter than a star 2 magnitude. A star 4 magnitude is brighter than a star 5 magnitude. Magnitude sequence for stars starting with the brightest is -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 magnitude, ... etc.

Magnitude of Stars

Star magnitude How Much Brighterthan a Sixth

Magnitude Star

Logarithmic scale of2.512 X between magnitude levels Starting at Sixth

Magnitude

1 100 Times 2.51 x 2.51 x 2.51 x 2.51 x 2.51

2 39.8 Times 2.51 x 2.51 x 2.51 x 2.51

3 15.8 Times 2.51 x 2.51 x 2.51

4 6.3 Times 2.51 x 2.51

5 2.51 Times 2.51 x

6

Six Star Magnitude Table

Fixed Stars

GALLANO, Lester C. EDILLO, Kenneth G. DUNTING, Christian Angelo A. DALAGUAN, Mark Jeffrey H.

Presented By: Group 2