How to Use a Computerized Telescope: Practical Amateur Astronomy

241 Pages·2002·6.14 MB·English

by  Covington M. A.

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PracticalAmateurAstronomy
HowtoUseaComputerizedTelescope
Computerizedtelescopeshavebroughtarevolutiontoamateurastronomy.Thenew
technologyhasopenedupobservingtomanywhowerepreviouslydauntedbythe
taskoflearningtheskyorusingstarcharts.Findinganastronomicalobjectbecomesa
quickoperationwithacomputerizedtelescope,allowingmoretimeforactual
observationoftheheavens.
HowtoUseaComputerizedTelescopeisthefirsthandbookthatdescribeshowtoget
yourcomputerizedtelescopeupandrunning,andhowtoembarkonaprogramof
observation.Itexplainsindetailhowtheskymoves,howyourtelescopetracksit,and
howtogetthemostoutofanycomputerizedtelescope.Packedfullofpracticaladvice
andtipsfortroubleshooting,ittranslatesthemanufacturers’technicaljargoninto
easy-to-follow,step-by-stepinstructions,aswellasincludingmanyoftheauthor’stried
andtestedobservingtechniques.Earlychaptersexplainhowtotestyourtelescope’s
optics,chooseeyepiecesandaccessories,takepicturesthroughyourtelescope,and
diagnoseoperationalproblems.Thesecondhalfofthebookthengivesdetailed
instructionsforthreeclassictelescopes:theMeadeLX200,CelestronNexStar5and8,
andMeadeAutostar(ETXandLX90).Besideshelpingownersandwould-be
purchasersofthesemodels,theinstructionsalsoprovideabasisofcomparisonfor
understandingnewertelescopes.
Amateurastronomerswillfindthisbookaninvaluablesourceofinformationand
adviceforgettingstartedwithanewcomputerizedtelescope.Concentratingmainlyon
telescopeoperationandtroubleshooting,itistheidealcompaniontoCelestialObjectsfor
ModernTelescopes,alsobyMichaelCovington,whichprovidesthereaderwith
suggestionsforinterestingcelestialobjectstoviewandadviceonhowtoobservethem.
Michael Covington,anavidamateurastronomersinceage12,hasdegreesin
linguisticsfromCambridgeandYaleUniversities.Hedoesresearchoncomputer
processingofhumanlanguagesattheUniversityofGeorgia,wherehisworkwonfirst
prizeintheIBMSupercomputingCompetitionin1990.Hiscurrentresearchand
consultingareasincludetheoreticallinguistics,naturallanguageprocessing,logic
programming,andmicrocontrollers.Althoughacomputationallinguistbyprofession,
heisrecognizedasoneofAmerica’sleadingamateurastronomersandishighly
regardedinthefield.Heistheauthorofseveralbooks,includingthehighlyacclaimed
AstrophotographyfortheAmateur(1985;secondedition1999)andCelestialObjectsfor
ModernTelescopes(2002),whicharebothpublishedbyCambridgeUniversityPress.
Theauthor’sotherpursuitsincludeamateurradio,electronics,computers,ancient
languagesandliteratures,philosophy,theology,andchurchwork.HelivesinAthens,
Georgia,U.S.A.,withhiswifeMelodyanddaughtersCathyandSharon,andcanbe
visitedontheWebatwww.covingtoninnovations.com.

Practical Amateur Astronomy
How to Use a Computerized Telescope
Michael A. Covington
CAMBRIDGEUNIVERSITY PRESS
Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo
Cambridge University Press
The Edinburgh Building, Cambridge CB2 8RU, UK
Published in the United States of America by Cambridge University Press, New York
www.cambridge.org
Information on this title: www.cambridge.org/9780521007900
© Michael A. Covington 2002
This publication is in copyright. Subject to statutory exception and to the provision of
relevant collective licensing agreements, no reproduction of any part may take place
without the written permission of Cambridge University Press.
First published in print format 2002
ISBN-13 978-0-511-33809-0 eBook (NetLibrary)
ISBN-10 0-511-33809-0 eBook (NetLibrary)
ISBN-13 978-0-521-00790-0 paperback
ISBN-10 0-521-00790-9 paperback
Cambridge University Press has no responsibility for the persistence or accuracy of urls
for external or third-party internet websites referred to in this publication, and does not
guarantee that any content on such websites is, or will remain, accurate or appropriate.
SoliDeogloria

Contents
Preface pagexv
Part I Telescopesingeneral 1
1
Welcometoamateurastronomy! 3
1.1 Usingatelescope 3
1.2 Learningthesky 4
1.3 Isacomputerizedtelescoperightforyou? 4
1.4 Materialyoucanskip 5
1.5 Doesthisbookcoveryourtelescope? 5
2
Howtheskymoves 6
2.1 Dailymotion 6
2.2 Coordinates 8
2.2.1 Rightascensionanddeclination 8
2.2.2 Declinationandlatitude 9
2.2.3 Someterminology 10
2.2.4 Othercoordinatesystems 10
2.2.5 Degrees,minutes,andseconds 11
2.2.6 Distancebetweenpointsinthesky 12
2.3 Annualmotion 12
2.3.1 Whytimeofyearmatters 12
2.3.2 Siderealtime 13
2.4 Timeofday 13
2.4.1 Solartimeandtimezones 13
2.4.2 HintsonusingUT 15
2.4.3 UTC,ET,andothersubtleties 17
2.5 SlowchangesinR.A.anddeclination 17
2.5.1 Precessionandepochs 17
2.5.2 Howprecessionworks 17
2.5.3 Propermotion 18
vii
Contents
3
Howtelescopestrackthestars 19
3.1 What’sinsideacomputerizedtelescope 19
3.1.1 Computer 19
3.1.2 Motors 20
3.1.3 Encoders 21
3.1.4 Digitalsettingcircles(DSC) 21
3.2 Altazimuthandequatorialmounts 21
3.3 Siteinformation 22
3.3.1 Whyit’sneeded 22
3.3.2 Obtainingsitedata 23
3.4 Whycompassesdon’tpointnorth 25
3.5 Settingupthetelescope 27
3.6 Choosingalignmentstars 28
3.7 AutomaticsetupwithGPS 29
3.8 Tripodsandpiers 29
3.8.1 Steadiness 29
3.8.2 Othertripodandwedgehints 30
3.8.3 Observatoriesandpermanentpiers 31
3.9 Pointingaccuracy 32
3.9.1 Whattoexpect 32
3.9.2 Factorsthataffectpointingaccuracy 32
3.9.3 Aligningthetelescopetubeinthemount 34
3.9.4 Thedouble-GOTOtrick 34
3.9.5 Meadehigh-precisionmode 35
3.9.6 TPointSoftware 35
3.9.7 Whatthetelescopeiscalculating 35
3.10 Computercontrol 36
3.11 Electricityfortelescopes 37
4
Usingequatorialmountsandwedges 39
4.1 Whyequatorial? 39
4.2 Mustfieldrotationbeeliminated? 39
4.3 Usinganequatorialmount 43
4.3.1 Settingupthemount 43
4.3.2 Roughpolar-axisalignmentwithoutsightingstars 43
4.3.3 FindingPolaris 44
4.3.4 Roughpolar-axisalignmentonPolaris 45
4.3.5 Initializingthecomputer 47
4.4 Refiningthepolaralignment 48
4.4.1 IteratingonPolarisandoneotherstar 48
4.4.2 Finealignment–thedriftmethod 49
4.5 Usingwedges 49
4.6 Trackinginequatorialmode 51
4.6.1 Trackingrates 51
viii