List of stars for navigation
Fifty-seven navigationalstarsand additionally the starPolarisare given a special status in the field ofcelestial navigation.Of the approximately 6,000 stars visible to thenaked eyeunder optimal conditions, these selected stars are among the brightest and span 38constellationsof thecelestial spherefrom thedeclinationof −70° to +89°. Many of the selected stars were named inantiquityby theBabylonians,Greeks,Romans,andArabs.
The starPolaris,often called either the "Pole Star" or the "North Star", is treated specially due to its proximity to the northcelestial pole.When navigating in theNorthern Hemisphere,a simple and quick technique can be used with Polaris to determine the observerslatitudeor, for larger maritime vessels can be used to calculate anygyrocompasserror that may exist. The other 57 selected stars have daily positions given innautical almanacs,aiding thenavigatorin efficiently performing observations on them. A second group of 115 "tabulated stars" can also be used for celestial navigation, but are often less familiar to the navigator and require extra calculations.
AlthoughPolariscan quickly and simply give a solution for latitude in the northern hemisphere, it can not participate in giving a position fix including longitude - it is for this reason it is excluded from the list of 57 primary navigational stars, each of which can be used to produce (in conjunction with each other, known time in relation to the prime meridian and a set of sight reduction tables) an actual latitudinal and longitudinal positional fix.
For purposes of identification, the positions of navigational stars — expressed as declination andsidereal hour angle— are often rounded to the nearest degree. In addition to tables,star chartsprovide an aid to the navigator in identifying the navigational stars, showingconstellations,relative positions, and brightness.
In practical use for sight reductions whilst at sea, tables can further assist a navigator by giving approximate altitudes (angles above the horizon) and azimuths (degrees as read from the compass) from an assumed or estimated position, usually helping to quickly determine the location and then quickly identify a particular navigational star that may be useful for a sight reduction.
Background[edit]
![](https://upload.wikimedia.org/wikipedia/commons/thumb/1/16/Nautical_almanac_left-hand_page.png/220px-Nautical_almanac_left-hand_page.png)
Under optimal conditions, approximately 6,000 stars are visible to the naked eye of an observer on Earth.[1]Of these, 58 stars are known in the field of navigational astronomy as "selected stars", including 19 stars of the first magnitude, 38 stars of the second magnitude, andPolaris.[1]The selection of the stars is made byHis Majesty's Nautical Almanac Officeand theUS Naval Observatory,in the production of the yearlyNautical Almanacwhich the two organizations have published jointly since 1958.[2]Criteria in the choice of stars includes their distribution across the celestial sphere, brightness, and ease of identification.[3]Information for another 115 stars, known as "tabulated stars", is also available to the navigator.[1]This list provides information on the name, approximate position in the celestial sphere, andapparent magnitudeof the 58 selected stars in tabular form and by star charts.
These stars are typically used in two ways by the navigator. The first is to obtain aline of positionby use of asextantobservation and the techniques of celestial navigation.[4]Multiple lines of position can be intersected to obtain a position known as a celestial fix. The second typical use of the navigational stars is to determine gyrocompass error by computing theazimuthof a star and comparing it to an azimuth measured using the ship's gyrocompass.[5]Numerous other applications also exist.
Navigators typically refer to stars using one of two naming systems for stars: common names andBayer's designations.[1]All of the selected stars have had a common name since 1953, and many were named in antiquity by the Arabs, Greeks, Romans, and Babylonians.[1]Bayer's naming convention has been in use since 1603, and consists of a Greek letter combined with the possessive form of the star's constellation.[1]Both names are shown for each star in the tables and charts below.
Each star's approximate position on the celestial sphere is given using theequatorial coordinate system.The celestial sphere is an imaginary globe of infinite size with the Earth at its center.[6]Positions on the celestial sphere are often expressed using two coordinates:declinationand sidereal hour angle, which are similar to latitude andlongitudeon the surface of the Earth. To define declination, the Earth'sequatoris projected out to the celestial sphere to construct thecelestial equator,and declination is measured in degrees north or south of this celestial equator.[6]Sidereal hour angle is a measurement between 0° and 360°, indicating how far west a body is from an arbitrarily chosen point on the celestial sphere called theFirst Point of Aries.Note that right ascension, as used by astronomers, is 360° minus the sidereal hour angle.
The final characteristic provided in the tables and star charts is the star's brightness, expressed in terms of apparent magnitude. Magnitude is a logarithmic scale of brightness, designed so that a body of one magnitude is approximately 2.512 times brighter than a body of the next magnitude.[Note 1][7]Thus, a body of magnitude 1 is 2.5125(~100) times brighter than a body of magnitude 6.[7]The dimmest stars that can be seen through a 200-inch terrestrial telescope are of the 20th magnitude, and very bright objects like the Sun and a full Moon have magnitudes of −26.7 and −12.6 respectively.[7]
Table[edit]
Key to the table | |
---|---|
Column title | Description |
No. | The number used to identify stars in navigation publications and star charts.[Note 2] |
Common name | The name of the star commonly used navigation publications and star charts. |
Bayer designation | Another name of the star which combines aGreek letterwith the possessive form of its constellation'sLatinname. |
Etymology of common name |
Etymology of the common name.[8] |
SHA | Sidereal hour angle (SHA),the angular distance west of thevernal equinox. |
Dec. | Declination,the angular distance north or south of thecelestial equator. |
App. magnitude |
Apparent magnitude, an indicator of the star's brightness. |
The table of navigational stars provides several types of information. In the first column is the identifying index number, followed by the common name, the Bayer designation, and the etymology of the common name. Then the star's approximate position, suitable for identification purposes, is given in terms of declination and sidereal hour angle, followed by the star's magnitude. The final column presents citations to the sources of the data,The American Practical Navigatorand the star's entry at theSIMBADdatabase, a project of theStrasbourg Astronomical Data Centeror CDS.
No.[Note 2] | Common name |
Bayer designation |
Etymology of common name | SHA | Declination | App. magnitude |
References |
---|---|---|---|---|---|---|---|
1 | Alpheratz | Andromedae | αthehorse's navel | 358 | N 29° | 2.06 | [8][9] |
2 | Ankaa | Phoenicis | αcoined name, "phoenix bird" in Arabic | 354 | S 42° | 2.37 | [8][10] |
3 | Schedar | Cassiopeiae | αthe breast (ofCassiopeia) | 350 | N 56° | 2.25 | [8][11] |
4 | Diphda | Ceti | βthe second frog (Fomalhautwas once the first) | 349 | S 18° | 2.04 | [8][12] |
5 | Achernar | Eridani | αend of the river (Eridanus) | 336 | S 57° | 0.50 | [8][13] |
6 | Hamal | Arietis | αfull-grownlamb | 328 | N 23° | 2.00 | [8][14] |
7 | Acamar | Eridani | θanother form of Achernar | 316 | S 40° | 3.2 | [8][15] |
8 | Menkar | Ceti | αnose (of thewhale) | 315 | N 04° | 2.5 | [8][16] |
9 | Mirfak | Persei | αelbow of thePleiades | 309 | N 50° | 1.82 | [8][17] |
10 | Aldebaran | Tauri | αfollower (of thePleiades) | 291 | N 16° | 0.85var[Note 3] | [8][18] |
11 | Rigel | Orionis | βfoot (left foot ofOrion) | 282 | S 08° | 0.12 | [8][19] |
12 | Capella | Aurigae | αlittle she-goat | 281 | N 46° | 0.71 | [8][20] |
13 | Bellatrix | Orionis | γfemale warrior | 279 | N 06° | 1.64 | [8][21] |
14 | Elnath | Tauri | βone butting with the horns | 279 | N 29° | 1.68 | [8][22] |
15 | Alnilam | Orionis | εstring of pearls | 276 | S 01° | 1.70 | [8][23] |
16 | Betelgeuse | Orionis | αthe hand ofal-Jauzā(i.e.Orion) | 271 | N 07° | 0.58var[Note 3] | [8][24] |
17 | Canopus | Carinae | αcity of ancient Egypt | 264 | S 53° | −0.72 | [8][25] |
18 | Sirius | Canis Majoris | αthe scorching one (popularly, the dog star) | 259 | S 17° | −1.47 | [8][26] |
19 | Adhara | Canis Majoris | εthe virgin(s) | 256 | S 29° | 1.51 | [8][27] |
20 | Procyon | Canis Minoris | αbefore the dog (rising before the dog star,Sirius) | 245 | N 05° | 0.34 | [8][28] |
21 | Pollux | Geminorum | βZeus' other twin son (Castor,α Gem, is the first twin) | 244 | N 28° | 1.15 | [8][29] |
22 | Avior | Carinae | ε1coined name | 234 | S 59° | 2.4 | [8][30] |
23 | Suhail | Velorum | λshortened form of Al Suhail, one Arabic name for Canopus | 223 | S 43° | 2.23 | [8][31] |
24 | Miaplacidus | Carinae | βquiet or still waters | 222 | S 70° | 1.70 | [8][32] |
25 | Alphard | Hydrae | αsolitary star of theserpent | 218 | S 09° | 2.00 | [8][33] |
26 | Regulus | Leonis | αthe prince | 208 | N 12° | 1.35 | [8][34] |
27 | Dubhe | Ursae Majoris | α1thebear's back | 194 | N 62° | 1.87 | [8][35] |
28 | Denebola | Leonis | βtail of thelion | 183 | N 15° | 2.14 | [8][36] |
29 | Gienah | Corvi | γright wing of theraven | 176 | S 17° | 2.80 | [8][37] |
30 | Acrux | Crucis | α1coined from Bayer name | 174 | S 63° | 1.40 | [8][38] |
31 | Gacrux | Crucis | γcoined from Bayer name | 172 | S 57° | 1.63 | [8][39] |
32 | Alioth | Ursae Majoris | εanother form of Capella | 167 | N 56° | 1.76 | [8][40] |
33 | Spica | Virginis | αthe ear of corn | 159 | S 11° | 1.04 | [8][41] |
34 | Alkaid | Ursae Majoris | ηleader of the daughters of the bier | 153 | N 49° | 1.85 | [8][42] |
35 | Hadar | Centauri | βleg of thecentaur | 149 | S 60° | 0.60 | [8][43] |
36 | Menkent | Centauri | θshoulder of thecentaur | 149 | S 36° | 2.06 | [8][44] |
38 | Rigil Kentaurus | Centauri | α1foot of thecentaur | 140 | S 61° | −0.01 | [8][45] |
37 | Arcturus | Bootis | αthe bear's guard | 146 | N 19° | −0.04var[Note 3] | [8][46] |
39 | Zubenelgenubi | Librae | αsouthern claw (of thescorpion) | 138 | S 16° | 3.28 | [8][47] |
40 | Kochab | Ursae Minoris | βshortened form of "north star" (named when it was that,[Note 4]ca. 1500 BC – AD 300). | 137 | N 74° | 2.08 | [8][48] |
41 | Alphecca | Corona Borealis | αfeeble one (in thecrown) | 127 | N 27° | 2.24 | [8][49] |
42 | Antares | Scorpii | αrival ofMars(in color) | 113 | S 26° | 1.09 | [8][50] |
43 | Atria | Trianguli Australis | αcoined from Bayer name | 108 | S 69° | 1.92 | [8][51] |
44 | Sabik | Ophiuchi | ηsecond winner or conqueror | 103 | S 16° | 2.43 | [8][52] |
45 | Shaula | Scorpii | λcocked-up part of thescorpion's tail | 097 | S 37° | 1.62 | [8][53] |
46 | Rasalhague | Ophiuchi | αhead of theserpent charmer | 096 | N 13° | 2.10 | [8][54] |
47 | Eltanin | Draconis | γhead of thedragon | 091 | N 51° | 2.23 | [8][55] |
48 | Kaus Australis | Sagittarii | εsouthern part of the bow (ofSagittarius) | 084 | S 34° | 1.80 | [8][56] |
49 | Vega | Lyrae | αthe falling eagle or vulture | 081 | N 39° | 0.03 | [8][57] |
50 | Nunki | Sagittarii | σconstellation of the holy city (Eridu) | 076 | S 26° | 2.06 | [8][58] |
51 | Altair | Aquilae | αflying eagle or vulture | 063 | N 09° | 0.77 | [8][59] |
52 | Peacock | Pavonis | αCoined from the English name of the constellation | 054 | S 57° | 1.91 | [8][60] |
53 | Deneb | Cygni | αtail of thehen | 050 | N 45° | 1.25 | [8][61] |
54 | Enif | Pegasi | εnose of thehorse | 034 | N 10° | 2.40 | [8][62] |
55 | Al Na'ir | Gruis | αbright one (of thesouthern fish's tail) | 028 | S 47° | 1.74 | [8][63] |
56 | Fomalhaut | Piscis Austrini | αmouth of thesouthern fish | 016 | S 30° | 1.16 | [8][64] |
57 | Markab | Pegasi | αsaddle (ofPegasus) | 014 | N 15° | 2.49 | [8][65] |
[Note 2] | *Polaris[8] | Ursae Minoris | αthepole (star) | 319 | N 89° | 2.01var[Note 3] | [8][66] |
Star charts[edit]
Navigators often usestar chartsto identify a star by its position relative to other stars. References like theNautical AlmanacandThe American Practical Navigatorprovide four star charts, covering different portions of the celestial sphere. Two of these charts areazimuthal equidistant projectionsof the north and south poles. The other two cover the equatorial region of the celestial sphere, from the declination of 30° south to 30° north. The two equatorial charts aremercator projections,one for the eastern hemisphere of the celestial sphere and one for the western hemisphere. Note that unlike familiar maps, east is shown to the left and west is shown to the right. With this orientation, the navigator can hold the star chart overhead, and the arrangement of the stars on the chart will resemble the stars in the sky.[1]
In the star charts, constellations are labelled with capital letters and indicated by dotted lines collecting their stars. The 58 selected stars for navigation are shown in blue and labelled with their common name, star number, and a Greek letter to indicate their Bayer designation. The additional 115 tabulated stars that can also be used for navigation are shown in red and labelled with a Greek letter to indicate their Bayer designation. Some additional stars not suitable for navigation are also included on the charts to indicate constellations, they are presented as unlabelled small red dots.
Equatorial stars[edit]
- Equatorial stars of the eastern hemisphere
The equatorial region of the celestial sphere's eastern hemisphere includes 17 navigational stars from Alpheratz in the constellation Andromeda to Denebola in Leo. It also includes stars from the constellations Cetus, Aries, Taurus, Orion, Canis Major and Minor, Gemini, and Hydra. Of particular note among these stars are "the dog star" Sirius, the brightest star in the sky, and four stars of the easily identified constellation Orion.
![Equatorial stars with SHA from 180 to 360](https://upload.wikimedia.org/wikipedia/commons/thumb/d/d3/Bowditch-equatorial-stars-180-360.svg/600px-Bowditch-equatorial-stars-180-360.svg.png)
- Equatorial stars of the western hemisphere
The equatorial region of the celestial sphere's western hemisphere includes 13 navigational stars from Gienah in the constellation Corvus to Markab in Pegasus. It also includes stars from the constellations Virgo, Bootes, Libra, Corona Borealis, Scorpio, Ophiuchus, Sagittarius, and Aquila. Thevariable starArcturus is the brightest star in this group.
![Equatorial stars with SHA from 0 to 180](https://upload.wikimedia.org/wikipedia/commons/thumb/c/cc/Bowditch-equatorial-stars-0-180.svg/600px-Bowditch-equatorial-stars-0-180.svg.png)
Northern stars[edit]
![Northern navigational stars](https://upload.wikimedia.org/wikipedia/commons/thumb/5/53/Navigational-stars-above-30-degrees-north.svg/400px-Navigational-stars-above-30-degrees-north.svg.png)
The 11 northern stars are those with a declination between 30° north and 90° north. They are listed in order of decreasing sidereal hour angle, or from thevernal equinoxwestward across the sky. Starting with Schedar in the constellation Cassiopeia, the list includes stars from the constellations Auriga, the Great and Little Bears, Draco, Lyra and Cygnus. The two brightest northern stars are Vega and Capella.
In the star chart to the right, declination is shown by the radial coordinate, starting at 90° north in the center and decreasing to 30° north at the outer edge. Sidereal hour angle is shown as the angular coordinate, starting at 0° at the left of the chart, and increasing counter-clockwise.
Southern stars[edit]
![Southern navigational stars](https://upload.wikimedia.org/wikipedia/commons/thumb/2/27/Navigational-stars-below-30-degrees-south.svg/400px-Navigational-stars-below-30-degrees-south.svg.png)
The 18 southern stars are those with a declination between 30° south and 90° south. They are listed in order of decreasing sidereal hour angle, or from thevernal equinoxwestward across the sky. Starting with Ankaa in the constellation Phoenix, the list includes stars from the constellations Eridanus, Carina, Crux, Centaurus, Libra, Triangulum Australe, Scorpio, Sagittarius, Pavo, and Grus. Canopus, Rigil Kentaurus, Achernar, and Hadar are the brightest stars in the southern sky.
In the star chart to the right, declination is shown by the radial coordinate, starting at 90° south in the center and decreasing to 30° south at the outer edge. Sidereal hour angle is shown as the angular coordinate, starting at 0° at the right of the chart, and increasing clockwise.
Footnotes[edit]
- Notes
- ^The value is actually the fifth root of 100, anirrational numberknown asPogson's Ratio.SeeTeaching Science.Vol. 52–53. Australian Science Teachers' Association. 2006. p. 44.Retrieved2010-09-06.
- ^abcThis list uses the assigned numbers from theNautical Almanac,which includes only 57 stars. Polaris, which is included in the list given inThe American Practical Navigator,is listed here without a number.
- ^abcdThe suffix var after the numeric value denotes avariable starwhose magnitude changes over time.
- ^For more information, see the articlechanging pole stars.
- Citations
- ^abcdefgBowditch, 2002, p. 249.
- ^"History of the Nautical Almanac".US Naval Observatory. Archived fromthe originalon 2018-08-20.Retrieved2011-01-23.
- ^Wright and Whitney, 1992, p. 273.
- ^Bowditch, 2002, pp. 301–303.
- ^Bowditch, 2002, pp. 271–274.
- ^abBowditch, 2002, p. 234.
- ^abcBowditch, 2002, p. 219.
- ^abcdefghijklmnopqrstuvwxyzaaabacadaeafagahaiajakalamanaoapaqarasatauavawaxayazbabbbcbdbebfbgbhBowditch, 2002, p. 248.
- ^"Alpheratz".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Alpha Phe".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Schedar".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Beta Ceti".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Achernar".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Hamal".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Acamar".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Menkar".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Mirfak".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Aldebaran".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Rigel".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Capella".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Bellatrix".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"bet Tau".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Alnilam".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Betelgeuse".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Canopus".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Sirius".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"eps CMa".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Procyon".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Pollux".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Eps Car".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"lam Vel".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Beta Car".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Alphard".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Regulus".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Dubhe".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Denebola".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Gienah".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Acrux".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Gacrux".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Alioth".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Spica".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Alkaid".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Agena".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Menkent".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Alpha Centauri".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Arcturus".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Alpha Librae".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Kochab".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Alphecca".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Antares".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Atria".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Sabik".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Shaula".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Rasalhague".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"gam Dra".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Kaus Australis".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Vega".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Nunki".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Altair".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Peacock".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Deneb".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Enif".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Alpha Gruis".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Fomalhaut".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Markab".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
- ^"Polaris".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2010-06-21.
References[edit]
- Bowditch, LL.D., Nathaniel(2002) [1802]. "15: Navigational Astronomy".The American Practical Navigator: An Epitome of Navigation(PDF).Bethesda, MD:National Imagery and Mapping Agency.ISBN0-939837-54-4.Retrieved2016-09-20.
- Strasbourg Astronomical Data Center (CDS)(2010)."SIMBAD".Set of Identifications, Measurements, and Bibliography for Astronomical Data.Strasbourg: University of Strasbourg.Retrieved2010-09-05.
- United States Army Research Office (2009).2010 Nautical Almanac.Arcata, CA: Paradise Cay Publications. pp. 28, leaf.ISBN978-0-939837-85-4.
- Wright, Frances; Whitney, Charles Allen (1992).Learn to navigate by the tutorial system developed at Harvard.Cambridge, Md: Cornell Maritime Press.ISBN0-87033-426-3.