Navigational stars Totally Explained

Everything about The Navigational Stars totally explained

The navigational stars are used in celestial navigation because they're some of the brightest celesital objects due to their high luminosities and/or their proximity to our solar system. Most of these stars are a subset of the list of brightest stars and are defined by convention and nautical tradition. One of the most prominent books on maritime navigation, Nathaniel Bowditch's American Practical Navigator, was the first to list these navigational stars in 1802, and they're still included in the 2002 bicentennial edition of the same book. They are also commonly listed on a page in the nautical almanac to aid navigators, typically on a tear-sheet that then serves as a bookmark throughout the year and is placed on the almanac page for the current 3-day period.
The coordinates of the stars are typically provided in the equatorial coordinate system, using declination and sidereal hour angle (SHA). By convention, these stars are numbered and listed West to East, for example by descending SHA. The nautical almanac lists 57 navigational stars, whereas the list in the American Practical Navigator contains 58 stars, with the additional star being Polaris. Also, the nautical almanac typically only provides declination to the nearest full degree in this list, since that's typically sufficient for locating the star with a sextant.

Navigational stars

Key

Column title	Description
No.	Index number of the star used in the list of selected navigational stars in the nautical almanac
Common name	The common (or proper) name of the star used in the nautical almanac and the American Practical Navigator
Magnitude	A logarithmic measure of the brightness of an astronomical object
Bayer designation	A stellar designation in which a specific star is identified by a Greek letter, followed by the genitive form of its parent constellation's Latin name
SHA	Sidereal hour angle (SHA) is one of the coordinates used in the equatorial coordinate system for describing the position of a point on the celestial sphere
Declination	The second coordinate used in the equatorial coordinate system
Distance (ly)	The distance from Earth to the star measured in light years
Meaning of name	A brief explanation of the meaning or origin of the common name for a star by Nathaniel Bowditch	α UMi	319	N 89°	430	the pole (star)	Polaris
7	Acamar	3.2	θ Eri	316	S 40°	120	another form of Achernar	Acamar
8	Menkar	2.5	α Cet	315	N 04°	220	nose (of the whale)	Menkar
9	Mirfak	1.82	α Per	309	N 50°	590	elbow of the Pleiades	Mirfak
10	Aldebaran	0.85 var ca. 1500 BC - AD 300)	Kochab
41	Alphecca	2.24	α₁ CrB	127	N 27°	75	feeble one (in the crown)	Alphecca
42	Antares	1.09	α Sco	113	S 26°	600	rival of Mars (in color)	Antares
43	Atria	1.92	α TrA	108	S 69°	420	coined from Bayer name	Atria
44	Sabik	2.43	η Oph	103	S 16°	84.1	second winner or conqueror	Sabik
45	Shaula	1.62	λ Sco	097	S 37°	700	cocked-up part of the scorpion's tail	Shaula
46	Rasalhague	2.10	α Oph	096	N 13°	47	head of the serpent charmer	Rasalhague
47	Eltanin	2.23	γ Dra	091	N 51°	150	head of the dragon	Eltanin
48	Kaus Australis	1.80	ε Sgr	084	S 34°	140	southern part of the bow (of Sagittarius)	Kaus Australis
49	Vega	0.03	α Lyr	081	N 39°	25	the falling eagle or vulture	Vega
50	Nunki	2.06	σ Sgr	076	S 26°	220	constellation of the holy city (Eridu)	Nunki
51	Altair	0.77	α Aql	063	N 09°	17	flying eagle or vulture	Altair
52	Peacock	1.91	α Pav	054	S 57°	180	coined from the English name of Pavo (constellation)	Peacock
53	Deneb	1.25	α Cyg	050	N 45°	3200	tail of the hen	Deneb
54	Enif	2.40	ε Peg	034	N 10°	670	nose of the horse	Enif
55	Al Na'ir	1.74	α Gru	028	S 47°	100	bright one (of the fish's tail)	Al Na'ir
56	Fomalhaut	1.16	α PsA	016	S 30°	25	mouth of the southern fish	Fomalhaut
57	Markab	2.49	α Peg	014	N 15°	140	saddle (of Pegasus)	Markab

Star charts

Star charts provide an aid to the navigator in locating the navigational stars among the constellations. It is useful to be able to identify stars by relative position - a star chart is helpful in locating these relationships.
Star charts are based upon the celestial equator system of coordinates, using declination and sidereal hour angle (or right ascension).Further Information

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