Patrick Moore’s Practical Astronomy Series Other Titles in this Series NavigatingtheNightSky AstronomyoftheMilkyWay HowtoIdentifytheStarsand TheObserver’sGuidetothe Constellations Southern/NorthernSkyParts1and2 GuilhermedeAlmeida hardcoverset MikeInglis ObservingandMeasuringVisual DoubleStars AstronomyoftheMilkyWay BobArgyle(Ed.) Part1:Observer’sGuidetothe NorthernSky ObservingMeteors,Comets,Supernovae MikeInglis andothertransientPhenomena NeilBone AstronomyoftheMilkyWay Part2:Observer’sGuidetothe HumanVisionandTheNightSky SouthernSky HowtoImproveYourObservingSkills MikeInglis MichaelP.Borgia ObservingComets HowtoPhotographtheMoonandPlanets NickJamesandGeraldNorth withYourDigitalCamera TonyBuick TelescopesandTechniques AnIntroductiontoPracticalAstronomy PracticalAstrophotography ChrisKitchin JeffreyR.Charles SeeingStars PatternAsterisms TheNightSkyThroughSmallTelescopes ANewWaytoCharttheStars ChrisKitchinandRobertW.Forrest JohnChiravalle Photo-guidetotheConstellations DeepSkyObserving ASelf-TeachingGuidetoFindingYour TheAstronomicalTourist WayAroundtheHeavens SteveR.Coe ChrisKitchin VisualAstronomyintheSuburbs SolarObservingTechniques AGuidetoSpectacularViewing ChrisKitchin AntonyCooke HowtoObservetheSunSafely VisualAstronomyUnderDarkSkies LeeMacdonald ANewApproachtoObservingDeepSpace AntonyCooke TheSuninEclipse SirPatrickMooreandMichaelMaunder RealAstronomywithSmallTelescopes Step-by-StepActivitiesforDiscovery Transit MichaelK.Gainer WhenPlanetsCrosstheSun SirPatrickMooreandMichaelMaunder ThePracticalAstronomer’sDeep-sky Companion LightPollution JessK.Gilmour ResponsesandRemedies BobMizon ObservingVariableStars GerryA.Good AstronomicalEquipmentforAmateurs MartinMobberley Observer’sGuidetoStellarEvolution TheBirth,LifeandDeathofStars TheNewAmateurAstronomer MikeInglis MartinMobberley FieldGuidetotheDeepSkyObjects LunarandPlanetaryWebcamUser’sGuide MikeInglis MartinMobberley (ContinuedafterIndex) Observing the Sun with Coronado™ Telescopes Philip Pugh Philip Pugh 4 Applewood Close Chippenham, Wiltshire SN14 0JG Wiltshire, UK [email protected] CoverIllustration:AmazingGracebyLarryAlvarez LibraryofCongressControlNumber:2006940069 PatrickMoore’sPracticalAstronomySeriesISSN1617-7185 ISBN-13:978-0-387-68126-9 e-ISBN-13:978-0-387-68127-6 Printedonacid-freepaper. ©2007SpringerScience+BusinessMedia,LLC Allrightsreserved.Thisworkmaynotbetranslatedorcopiedinwholeorinpartwithoutthewritten permissionofthepublisher(SpringerScience+BusinessMedia,LLC,233SpringStreet,NewYork, NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use inconnectionwithanyformofinformationstorageandretrieval,electronicadaptation,computer software,orbysimilarordissimilarmethodologynowknownorhereafterdevelopedisforbidden. The use in this publication of trade names, trademarks, service marks, and similar terms, even if theyarenotidentifiedassuch,isnottobetakenasanexpressionofopinionastowhetherornot theyaresubjecttoproprietaryrights. Observing the Sun, along with a few other aspects of astronomy, can be dangerous. Neither the publishernortheauthoracceptsanylegalresponsibilityorliabilityforpersonallossorinjurycaused, orallegedtohavebeencaused,byanyinformationorrecommendationcontainedinthisbook. 987654321 springer.com This book is dedicated to my wife, Helga, and daughter, Marcela, who gave me a Coronado Personal Solar Telescope (PST) as a 50th birthday present. Preface Scientists will often tell you that now is the most exciting time for a particular interest. We will always have just discovered or invented something that will “revolutionize”somethingortheother.ThecomputeronwhichIamtypingthis, for example, is four times faster than its predecessor and slightly cheaper. However,thelastdecadeorsohasseensomeadvancesthathavechangedthe faceofamateursolarastronomy.Professionalresearchershavebeenusingmany of the tools and techniques for years but now they are available to amateurs as well. Theuseofdigitalphotographyandcomputershaschangedallastronomy,not just amateur solar astronomy, and it has certainly made a lot more techniques available for photographing the Sun. Secondly,theuseof“whitelight”solarfiltershasimprovedthedetailthatcan be seen on the solar surface. In the past, the only technique that was available was projection onto a piece of white paper or card. Thirdly, the use of hydrogen alpha filters has recently hit the “affordability barrier”of$500or£500formanyamateurastronomers.TheCoronadoPersonal Solar Telescope (PST) is a real breakthrough product that has now brought a fascinating branch of astronomy within the reach of many people. In recent months, the same technique has been applied to calcium K filters. Like many amateur astronomers, I became interested in the Sun as an afterthought. Living in southern England, there is a period of about 7 weeks (more if you live in the Midlands or North) where there is little astronomical darkness at night. If you are at work or in education, it is practical to observe only on Friday and Saturday nights unless you have the ability to forgo sleep. The Moon and the Venus can sometimes be viewed in daylight and the brighter vii viii Preface planets and double stars can be viewed in twilight, yet the main object viewable in the day has to be the Sun itself. The main drawback of viewing the Sun is safety. The Sun is not just bright, it isverybrightandevenlookingstraightatitwithouttelescopeorbinocularscan damage your eyesight. Using a telescope or pair of binoculars without due care can cause blindness, and lack of attention can cause damage to your telescope. Apart from being a welcome distraction that can be enjoyed during daylight withouttheneedforpristineviewingconditions,theSunisaninterestingobject in its own right. It may appear predictable but unlike the Moon and many other objects, it is anything but. It might follow certain patterns but its exact appearance on a day-to-day basis is far from predictable. Indeed, the hydrogen alpha view of the Sun can change in minutes, rather than hours or days, unlike most astronomical objects. FigureP.1. SunthroughahydrogenalphaPST.PhotobyNickHowes. Preface ix FigureP.2. Sun throughacalciumK PST.PhotobyHiram Villarreal. TheSunistheonlychanceforamateurstoseeastarclose-up.Overthepastfew years,thediscsofrelativelynearbyredgiantstarshavebeenimagedwithprofes- sionaltelescopes,butthisisnotavailabletoamateurastronomers(atleastnotyet). Whether you are interested in looking at the Sun from a scientific point of view or are interested in what is visible in amateur equipment, it is something you can get hours of enjoyment out of. Ihaveactuallybeenamazedmyselfwhatitispossibletodowithevenalimited budget.Justasenterprisingamateurshavetakensomegreatphotosofthenight sky objects, so many have turned their attention to the Sun. The ability to buy and use expensive telescopes and photographic equipment is an advantage, but nice photographs can be obtained with modest equipment, as Figures P.1 and P.2 show. Purpose This book discusses the various options available for viewing and imaging the SunusingCoronadoequipment.Itcoversthetelescopesfromtheentry-levelPST forthekeenbutfinanciallychallengedamateurtothetopoftherangeMaxScope 90. It is the PST and MaxScope 90 that I have chosen to analyze in detail, but I havealsoprovidedsufficientinformationabouttheothertelescopestohelpyou decide which purchase is most appropriate for you and how to get the best use out of it. Apartfromtheconvenienceofownership,IhavecoveredthePSTindetail,as it is the telescope that people are most likely to buy. To demonstrate the top of the range, Larry Alvarez has done a full write-up on the MaxScope 90. x Preface Although the subject of the book is the Coronado range of telescopes and filters, I have included information about other manufacturers’ equipment that can be used separately or in conjunction with Coronado products. Neithermyselfnormycoauthorshavebeenabletotesteverypossiblecombi- nation of equipment with accessories, but we have tried a reasonable amount of ideas that will help you to decide on a purchase and get the most from it. Even if you are not interested in an imminent purchase, you may find the picturesinterestingandyoumaygettheopportunitytoseethroughthetelescopes at a public event. Areas of Expertise As most of my experience has been with the PST, eight coauthors have added information in their specialist areas in the following table. CoAuthor AreasofExpertise LarryAlvarez MaxScope90 CameranAshraf Double-StackedPST MarcelloLugli Separatenon-Coronadofilters NickHowes Imaging,PSTCaK JeffPettit DayStarfilters MikeTaormina CaK70 HiramVillarreal PSTCaK JohnWatson MountingbracketforthePST