BROWN'S STAR ATLAS SHOWING ALL THE BRIGHT STARS WITH FULL INSTRUCTIONS HOW TO FIND AND USE THEM FOR NAVIGATIONAL PURPOSES AND DEPARTMENT OF TRADE EXAMINATIONS GLASGOW BROWN, SON & FERGUSON, 52 DARNLEY LTD., NAUTICAL PUBLISHERS STREET All rights reserved Revised Edition 1969 New Edition 1977 ISBN 85174 271 © 1977 BROWN, SON & FERGUSON, LTD., GLASGOW, Printed and Made in Great Briiail1 G41 2SG PREFACE RECENT YEARS have witnessed a considerable development of interest in Stellar Navigation This is due in some measure to the fact that it now forms an important Department of Trade examinations, the examinations feature of the but both the increased interest and its inclusion in are results of the further fact that its importance and necessity are becoming more clearly recognised, and that it is now acknowledged to be an essential factor in all navigation This atlas is intended for the use and ~idance recognise the principal BRIGHT of those who wish to be able to stars and to become proficient star navigators; and while it is of interest to those going up for examination, it is essentially a book for practical use at sea I T is designed to help beginners to trace out the principal constellations and PART BRIGHT stars projected on the plane of a meridian, and may be used by observers in any latitude A study of these maps not only BRIGHT stars The six large maps show all the facilitates the recognition of the stars, but also fixes in the mind an approximate know- ledge of their positions in the heavens, and of the times when they are available for observation the BRIGHT The fact that the maps are continuous, and show in unbroken succession all stars, is believed to be a good feature constellations Mr DENNING, PART are further illustrated on special maps In addition to this the principal The maps have been drawn by F.R.A.S II deals with the use of the stars in practical navigation, and the various methods of finding a ship's position, and the deviation of the compass are eXplained: also the identification of a star by figure, Star globe and ABC Tables All references, in these pages, to the "Nautical Almanac" must be taken as referring to Brown's Nautical Almanac and to the Nautical Almanac issued by H.M Nautical Almanac Office, Royal Greenwich Observatory CONTENTS -PART I.-How TO FIND THE STARS PAGE Explanation of the Maps, and directions for tracing and recognising the principal constellations and bright stars The Declination, Right Ascension, First Point of Aries, Sidereal Hour Angle Naming of Stars, Magnitudes of Stars, Stars that not rise above Observer's Horizon List of Fixed Stars for July 1, 1!)76 Stars that are always above the Horizon, or Circumpolar ~tars Table showing times when Stars in each Map are near the meridian on certain dates Star Map No 1,-R.A OOhto 04h; S.H.A 3000 to 3600 2,04h to 08h; 2400 to 3000 " " " " " 308h to 12h; 1800 to 2100 , " 1200 to 1800 " " " 4,- " 12h to 16h; " " " " " OCQo to 1200 5,16h to 20h; " 0000 to 0600 " " " 6,- " 20h to 24h; " " " " " How to trace the Principal Constellations and Bright Stars - Key Map of constellation Ursa Major Cassiopeia - " " " " Orion " " " " Leo - " " " " Cygnus and Lyra " " " " Crux Australis (Southern Cross) " " " " Planets, Notes on - - - - - - - - - - - - PART - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - I I.-STAR The Local Hour Angle of Aries - To find what Bright Stars are near the Meridian To find the time at which a Star will cross the Meridian Remarks on observing Star Altitudes Latitude by Meridian Altitude of a Star Latitude by Ex-Meridian of a Star Latitude by Pole Star Time Azimuths of Stars Altitude Azimuth of a Star Longitude from Altitude of t Star Simultaneous Sights of Two Stars used for J ntercepts Cosine-Haversine Method Star Identification Solution by A.B.C Tables Graphic Solution Greek Alphabet - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 22 22 22 22 11 11 11 21 22 22 23 25 26 PROBLE~rs - - - - - - - - - - - - - - - - - - - - - - - - - - • - - - - - - - - - - - - - - - - - - - - - - - - - - Q - - - 28 29 30 32 34 36 38 40 42 44 45 47 48 49 49 50 I PART HOW TO FIND THE STARS Explanation of the maps, and directions for tracing and recognising the principal constellations and bright stars THE MAPS are designed in such a manner that sections of the heavens are presented for observation in rotation On each map the central portion is the part specially presented for study, and is printed with white stars on a dark ground, this being most striking to the eye Each of these sections shows a portion of the heavens from Pole to Pole, included between Meridians, hours or 60° apart The whole firmament thus occupies six maps On each side of these sections, for convenience of reference, the stars in the adjacent regions of the heavens are shown To avoid overcrowding the maps, only the brighter stars, or those used in navigation, appear The observer must imagine himself to be holding the map overhead and looking at it from below, the North point of the map being directed to the North The central North and South line then represents the meridian, and he will easily understand that the right hand half of each map represents the Western part of the heavens and the eft hand portion the Eastern part It is not possible to represent the celestial sphere on a plane surface such as a nap, and at the same time to preserve the relative distances and bearings of all the n EXPLANATION stars from each other MAPS, ETC In all maps of the stars there must be a certain amount of distortion or misplacement; llustrated OF only on a globe can their relative positions be accurately In the method of projection here chosen the apparent misplacement is least in the central portion of the maps, and this is the reason that attention is directed to that part Otherwise the whole heavens might have been presented on two maps only As the position of a place on the earth's surface is fixed by its Latitude and Longitude, so the position of a point in the celestial sphere can be fixed by its Right Ascension and Declination, or by its Sidereal Hour Angle (S.H.A.) and Declination The Declination of any object is its angular distance North or South of the Equinoctial or Celestial Equator, measured along the meridian to Latitude on the earth's surface It thus corresponds On the maps the Equinoctial is the line through the centre from East to West First Point of Aries.-In practice, this is nearly always shortened to "Aries" It is that point at which Sun, travelling in the Ecliptic, crosses the Equinoctial when going from South to North Declination passing through the point The name is usually applied to the celestial meridian It is of great importance because all Right Ascensions, and all Sidereal Hour Angles of stars, are measured from this point, or hour circle The Right Ascension of a celestial object is the arc of the Equinoctial between the First Point of Aries and the meridian of the object, always reckoning eastward from the First Point of Aries o to 24 hours, or 360° Right Ascension is reckoned in sidereal time, eastward from Therefore, when we say a star's Right Ascension is hours, or 13 hours, etc., we mean that it is on a meridian hours or 13 hours, etc., East of the First Point of Aries On the large maps meridians are drawn for each hour The Sidereal Hour Angle (S.H.A.) of a star or planet is its westerly distance, in are, from Aries It is measured as an angle at the Pole, or as the intercepted arc of the Equinoctial, between the hour circle of Aries and the hour circle of the star or planet Its value lies in the fact that the Hour Angle of any star, at any instant, can be found by adding its S.H.A to the Hour Angle of Aries at that instant formula: H.A Star=S.H.A Star+H.A Aries We thus have an invariable EXPLANATlON OF MAPS, Q ETC Naming of Stars Constellations.-A name Constellation consists of a number of stars grouped under one Many of these names have been handed down from the earliest days The stars belonging to a constellation are distinguished by prefixing to each one a letter of the Greek alphabet Thus we have IX Orionis, ~ Orionis, IX Ursae Majoris, etc The star that appears to be the brightest in any constellation is usually alpha (01:) of that constellation; alphabet the second brightest being beta (~), and so on in sequence of the Greek See page 49 The constellation names are printed in capitals on the maps Some of the principal constellations are also shown on special maps, with the Greek letters attached to each star In addition to the above style of distinguishing stars most of the principal stars have been given proper names; thus is known as DUBHE, and so on IX Orionis is also named BETELGUESE, 01: Ursae Majoris These names are printed on the maps in smaller type, but only the more familiar ones have been given, so as to avoid overcrowding the maps with names A full list of the names will be found on page Magnitude of Stars The magnitude or brilliancy of each star is indicated by a number, and the brighter the star, the less this number will be The magnitude numbers are now given to tenths, that is, to one decimal figure (see Table of Stars), and a star of magnitude 1·5 is one-tenth of a magnitude brighter than one of magnitude 1·6 Two of the stars are so bright that their magnitudes are denoted by minus numbers, as they are brighter than magnitude magnitude -1·6 o Sirius, the brightest of the fixed stars, is of Canopus is next in brilliancy with magnitude -0·9 Stars that not rise above the Observer's Horizon When an observer's latitude and a star's declination have different names and their sum exceeds 90°, the star will not rise above the horizon in that latitude This can 'tABLE OF STARS, ETC Right Ascension r OG OG f3 f3 MAP I OG tOC y OG f3 OG and Declination of Fixed Stars for and Maps on which they appear Star's Name 04 05 05 05 05 05 05 05 05 06 06 06 06 06 07 07 07 07 35 13 15 24 25 35 41> 54 58 22 23 37 44 58 07 33 38 44 291 281 281 279 278 276 275 271 270 264 264 260 258 255 253 246 245 244 21 38 15 01 47 14 06 31 32 34 08 54 57 34 08 43 28 01 r r I I Dec 358 12 353 43 350 12 349 23 342 53 327 19 335 47 329 22 328 31 313 19 309 19 1977, 1, I I I I I N 28 S 42 N 56 S 18 N 35 N 89 S 57 N 42 N 23 N 40 N 49 58 27 25 07 30 10 21 13 21 52 47 N S N N N S S N N S S N S S S N N N 16 18 45 28 44 17 52 16 16 28 26 31 28 28 14 59 20 35 13 57 24 57 57 41 25 41 56 21 56 17 05 I 1·8 2·2 1·3 2·3 2·4 2'0 2·2 9 10 10 11 11 11 13 26 07 19 00 02 48 221 218 208 205 194 194 183 45 23 13 19 53 25 02 S S N N N N N 69 08 12 19 56 61 14 37 33 05 57 30 52 42 - Gacrux A,,~ Y Crucis f3 Crucis Mimosa e: Ursae Major Alioth 1: Ursae Major Mizar OG Virginis Spica \ 1J Ursae Major Alkaid '13 Centauri Hadar toc Boot!, A,"a,,, OG Centauri Rigil Kent 13 Ursae Minor Kochab OG Coronae Borealis Alphecca 1·1 1·6 1·5 1·7 2·2 1·2 1'9 0,9 0'2 0·1 2-2 2·3 12 12 12 12 13 13 13 14 14 14 14 15 25 30 46 53 23 24 47 02 14 38 51 34 173 172 168 166 159 159 153 149 146 140 137 ]26 40 32 24 45 15 01 21 27 21 30 20 35 S S S N N S N S N S N N 62 56 59 56 55 11 49 60 19 60 74 26 58 59 33 05 03 02 26 15 18 44 15 47 1·2 ],9 2·1 0·1 0,9 16 16 17 18 19 28 46 34 38 50 113 108 96 80 62 00 27 32 38 35 S S N N N 26 68 12 38 08 23 59 35 43 49 2·1 ] ,3 2·2 2·2 1.3 2.6 20 24 20 41 22 07 22 41 22 56 23 03 54 49 28 19 15 14 03 50 ]8 41 54 06 S N S S S N 56 45 47 47 29 15 49 12 05 01 45 05 roc r OG OG OG OG Soo"," A"a", Trian~'lli Australis Atria Ophiuchi Rasa/hague Lyrae Vega Aquilae '" Altair fOG Pavonis Peacock Cygni Deneb Gruis , AI Na'ir f3 Gruis 13 Gruis OG Piscis Australis Foma/haut OG Pegasi Markab l OG OG I , Miap/acidus Hydrae , Alphard Loon" R,gal•• y Leonis Aigeiba f3 Ursae Major Merak OG Ursae Major Dubhe f3 Leonis Denebo/a OG MAP VI S.H.A , 1·1 0·3 0·2 1·7 1·8 1·8 1·9 0·1/1·2 2·1 2'0 -0,9 1·9 -1-6 1-6 2·0 1·6 0,5 1·2 (13 Carinae MAP V I Tauri a MAP IV R.A 2·2 2·4 2'5 2·2 2-4 2·1 0·6 2·2 2·2 2·3/3· 1'9 a MAP III I Andmm"'~ Alph"a" Phoenicis Ankaa Cassiopeiae Schedar Ceti Diphda Andromedae Mirach Ursae Minor Polaris &-idani A,h,,~ Andromedae AIm.'k Arietis Hamal Perse! 11go1 Pers":l Mirfak f3 Orionis MAP II Mag h m 00 08 00 25 00 39 00 42 01 08 02 11 01 37 02 03 02 06 03 07 03 23 Aldebaran Rigel OG Aurigae Capella Y Orionis Bellatrix f3 Tauri Elnath e: Orionis Alnilam A/nitak Orionis OG Orionis Bete/guese f3 Aurigae Menkalinan ( Canis Major Mirzam OG Carinae Canopus Y Geminorum Athena Cani, M.jo, Ski" e: Canis Major Adhara Canis Major Wezen OG Geminorum " Castor OG Canis Minor Procyon f3 Geminorum .• Pollux OG I July I I I I I, , I I i I I I I I I, EXPLANATION OP MAPS, ETC be seen by inspection from the maps, as the parallels are drawn for every 10°; therefore, if from the observer's latitude to the position of the star is over 90 , it will not appear above his horizon Stars that are always above the Horizon, or Circumpolar Stars If the observer's latitude and a star's declination have the same name and their sum exceeds-flO°, that star will always be above the horizon, describing a circle round the elevated pole of the heavens The two last rules may conveniently be put thus :-subtract and thus get the co-latitude your latitude from 90 All stars in the opposite hemisphere with declination greater than the co-latitude will not arise above the horizon, and all stars in the same hemisphere with declination greater than co-latitude will be circumpolar, that is, will describe a circle round the pole always above the horizon In London (latitude about 5ltO N., co-latitude O 8Si ) all stars in the Southern Hemisphere with declination greater than 8Sio will always be below the horizon, and all stars in the Northern Hemisphere with declination greater than 8Sio will be circumpolar It must be noted here that stars seldom become visible until 5° or so above the horizon On the following page is a Table giving the times on certain dates when the stars on the central portion of each map are near the meridian Every day each star crosses the meridian about minutes earlier than on the preceding day, that is, roughly, about hours earlier per month Stars, therefore, which are near the meridian on any date, will occupy the same position about hours earlier on the same day of the following month ''''hen comparing the maps with the sky, regard must be had to the observer's latitude, and to the rules for stars above the horizon as given (3 EXPLANATION OF MAPS, E'rc Table showing the times when the stars on each map are near the meridian on certain dates 4hrs 2hrs A.M A.M I MIDNIGHT lOhrs 8hrs P.M P.M Map I " II August October 22 " September 22 October November December " III December " January " IV February March V April " VI June " " " " May July " " " " " February April June August 22 " " " " " November 22 December January February March " " May " July " September" April June Augu:-Jt October 22 " " " " " I From the above Table the student should not have much difficulty in selecting the particular throughout maps which show the stars near the meridian at any time of the day the year 35 LATITUDEBY EX-MERIDIAN Notes.-Ex-Meridian subtractive Reduction It is always is taken from Ex-Meridian Tables from Observed Zenith Distance Position Line is at right angles to line of Azimuth, and passes through calculated Latitude and D.R Longitude ALTERNATIVELY, the LATITUDEcould have been calculated by the Ex-meridian Formula, and this is now shown Hour Angle 8° 45'0', DATA (From previous Example.) 32' N., Dec 52° 40' S Latitude (D.R.)· 13 • Observed Z.D 66° 43' N Hour Angle Latitude Declination 8° 45·0' 13° 32' 52° 40' log hav log coso log coso ·76487 ·98777 ·78280 log hav 7·53744 Observed Z.D 66° 43' Nat hay 0·00343 Nat hav 0·30236 Meridian Zen Dist Nat hay 0·29893 = 66° 17' The Position Line could have been found by Intercept The method, using the same data as before, is shown below H.A Latitude Declination Lat + Dec 8° 45'0' 13° 32' N 52° 40' S 66° 12' log hay log coso log coso ·76487 9,98777 ·78280 log hay 7·53744 Nat hay 0·00343 Nat hay 0·29832 Calculated Zen Dist Nat hay 0·30175 = 66° 38·5' Calculated Zen Dist 66° 38'5' Observed Zen Dist 66° 43' S6° 35!' E Line runs 084°-264° Azimuth S 6° E 4·5' away Intercept I~nsition + + T through position Lat = (174° 13° 36'5' T.) N., Long Sb LATITUDE BY POLE STAR Latitude by Pole Star In the Northern hemisphere the Pole Star affords an easy method of finding the latitude The practical working is as follows :Take the altitude with your sextant Apply the usual corrections to it to obtain the true altitude Find the Local Hour Angle of Aries at the moment of observation From the Pole Star Tables given in Brown's Nautical Almanac and the Admiralty Nautical Almanac, take out ao, aI' as corrections and add them to the true altitude already obtained: ao corresponding to L.H.A Aries; a1 corresponding to latitude; a according to the month and the latitude Subtract 10 from the result The remainder is the latitude EXAMPLE 1961, December 21st, about 02 hrs at ship in D.R position 39° N., 148° 54' W., true altitude of Polaris was 39° 09' Required, Latitude Chronometer keeping G.M.T showed llh 53m and Position Line Dec 21d llh 53m - G.H.A Aries - increment - - - Longitude L.H.A Aries 254° 46·5' 13 17·2 - - 268 03,7 148 54 W- - - 119 09,7 True Alt Polaris - L.H.A Aries 119° Latitude 39° N December - subtract 1° - - 39° 09' 59·1 (ao) 0,4 0'4 (aI) (a2) 40 08,9 39 08,9 Latitude Azimuth (from Pole Star Azimuth Table) 358,8° T Ship is on a position line running 089° 269° T through position 39° O~'9' 148° 54' W N.• 'l'lME AZIMUTH OF 37 STARS Time Azimuth of Stars The stars offer a particularly useful and easy means of ascertaining the deviation of the compass at night by timc azimuths The altitude is not required, therefore it is immaterial whether the visibility of the horizon is poor o.r whether it is clearly defined It is only necessary that the compass bearing be correctly observed, and that the time of observation and the name of the star be known There should be no difficulty in choosing a suitable star if the observer has studied the maps and directions in Part I of this atlas Stars are in the best position for azimuth when not more than about 80° from the horizon Burdwood's Time Azimuth Tables for latitudes 80° to 60° N or S and Davis's for latitudes 0° to 80° N or S., can be used for any star whose declination does not materially exceed 28° Two books of tables by Percy L H Davis, giving both altitude (called Alt-az tables) have since been published and azimuth They are for latitudes 0° to 80° N or S and for 80° to 64° N or S., the declination limits of both being 24° The method of finding the true azimuth is the same for all four books.' The working is done as follows :Find the L.H.A Aries as previously explained Underneath it write down the star's S.H.A The sum of them is the star's hour angle To find the star's true azimuth from the tables the elements required are Latitude Declination and Hour Angle Turn up the page on which is given your latitude and the star's declination, being careful to note whether they have the same or contrary names Take out the azimuth with the Declination of the observed body, and corresponding with its Hour Angle Name the true azimuth with the same name as the Latitude, H~O· If azImuth exceeds ]80°, subtract and West up to it from 860° and name the remainder East 38 AZIMUTH OF STARS 1961, June 19th, about chronometer compass olh 30m ship's time,.in D.R Lat 42° S., Long 131° E.) showed (18d.) 16h 42m G.M.T and star Diphda bore 0996·5' =054 56,5 L.H.A.· L.H.A • Lat Dec 054° 56·5' 42