Go-To Telescopes Under Suburban Skies (Patrick Moore's Practical
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Patrick Moore’s Practical Astronomy Series For other titles published in this series, go to http://www.springer.com/series/3192 Go-To Telescopes Under Suburban Skies Neale Monks 123 Neale Monks HP4 3EH Berkhamsted Hertfordshire United Kingdom ISSN 1431-9756 ISBN 978-1-4419-6850-0 e-ISBN 978-1-4419-6851-7 DOI 10.1007/978-1-4419-6851-7 Springer New York Dordrecht Heidelberg London Library of Congress Control Number: 2010932673 © Springer Science+Business Media, LLC 2010 All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer Science+Business Media, LLC, 233 Spring Street, New York, NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) Preface This book is a compendium of targets for owners of go-to telescopes observing from suburban and exurban (even further out than suburban) locations. Unlike most other books about the deep sky, this book doesn’t contain sky charts or star hops, since those aren’t needed by owners of go-to telescopes. Instead the aim is to pro- vide information on as many interesting stars, star clusters, nebulae, and galaxies as possible. All are visible from suburban or exurban locations, and none require an aperture greater than 200 mm. Within each season there are three categories of deep sky objects, and one cat- egory for stars. The section on wintertime objects, for example, contains 77 deep sky objects and 28 stars. The first of the deep sky object categories is one for show- piece objects; then there’s a category for interesting rather than exceptional objects, and finally a category of objects that are obscure or difficult to see under suburban conditions. The stars included in each chapter include a variety of double stars, variable stars, unusually colorful stars, and stars that feature in unusual asterisms or clusters. Sev- eral stars are included because of their historical or scientific importance. Unlike deep sky objects, stars are largely unaffected by light pollution. This makes them especially rewarding targets for suburban observers. Although written for owners of go-to telescopes, there’s nothing to stop owners of non-computerized telescopes from using this book. Used alongside a star chart or planetarium program, this book could help owners of traditional telescopes get ideas about what’s worth observing on a particular night. One key difference between this book and most other deep sky books is the assumption that the observer will be working under light-polluted skies and using a telescope with an aperture of 200 mm or less. For the purposes of this book, a v vi Preface 200 mm telescope is considered a ‘large’ telescope, one around 150 mm a ‘medium’ telescope, and anything less than 100 mm a ‘small’ telescope. Indeed, most comments on the brightness of objects will be subjective ones related to aperture and light pollution. Very little will be said about visual magni- tudes, since with deep sky objects these values are often very misleading. Instead the reader will be told about how bright the object seems, how much contrast there is between the background sky and the object itself, and whether light pollution filters help to make the object easier to see. Light pollution is one of the two most limiting issues that affect suburban astron- omy (the other being obscuring objects such as trees and buildings close to the hori- zon). Most of the author’s observing was done in three different places, all subject to light pollution of varying severities. My observing in England is done in Berkham- sted, a little over 30 miles from London, and with skies that rate about 6 on the Bortle scale of sky darkness. In the United States, my observing from suburban Lin- coln, Nebraska, is under skies of similar quality. Exurban Lincoln is quite a bit better, with the skies at the Olive Creek Recreation Park about 10 miles southwest of the city between 3 and 4 on the Bortle scale. Although this is primarily a book about northern hemisphere observing, some southern sky objects are included. In my case, these objects were mostly observed during vacations to Hutchinson Island, not far from Stuart, Florida, and at a lati- tude of 27◦ north. While many of these objects can still be seen as far north as the American Midwest, observers as far north as southern England will find southern sky targets difficult or impossible to see. Where latitude is relevant to observing an object, it is mentioned in the text, usually with some indication of how far an object rises above the southern horizon, if it does so at all. This isn’t a book about hardware. But that said, two pieces of hardware are so useful that suburban astronomers should consider owning them. The first is a light pollution filter. There are various kinds, each with its own strengths and weaknesses. The second must-have item is a reducer-corrector, a lens that allows Schmidt– Cassegrain telescopes (SCTs) to behave almost like wide field telescopes. More will be said about both of these accessories in the first chapter. Finally, some words of thanks. The eyepiece simulations used here to suggest what would be seen through a telescope were put together using Starry Night Pro Plus, courtesy of Simulation Curriculum Corp, and AllSky data, courtesy of Main- Sequence Software Inc. The author must thank Pedro Braganca and Doug George for making these excellent tools available to him. The author also wishes to thank Michelle Meskill and Kevin Kawai at Celestron for providing him with photos of Celestron hardware and offering useful comments on the text, particularly with regard to the use and maintenance of go-to telescopes. More valuable comments on the text came from David W. Knisely at the Prairie Astronomy Club in Lincoln, Nebraska. His comments on the benefits of light pollution filters were especially useful. Finally, the help that John Watson and Maury Solomon provided getting this Preface vii project off the ground cannot be overstated. To all of them, thank you for your help, patience and support. Two amateur astronomers passed away while I was putting together this book, David Brokofsky (of Lincoln) and David Schultz (of Omaha). In different ways, they each helped me enjoy this hobby and develop my observing skills. To both of them: Clear skies! Contents 1 Introduction ................................................... 1 HowtoUseThisBook........................................... 1 WhyNGCandSAONumbers?.................................... 2 ObservingfromtheSuburbsandExurbs............................ 3 LightPollutionFilters............................................ 5 BroadbandFilters............................................. 5 NarrowbandFilters ........................................... 6 LineFilters................................................... 7 UsingLightPollutionFilters...................................... 8 Reducer-Correctors.............................................. 8 DarkAdaptation................................................ 10 GettingtheMostfromaGo-ToTelescope........................... 10 2Winter........................................................ 15 ShowpieceObjects .............................................. 16 NGC224(M31,AndromedaGalaxy)............................ 16 NGC 1502 (Kemble’s Cascade Cluster) – See Also SAO 12969 . 18 NGC 1535 (Cleopatra’s Eye) . 19 NGC 1976 and 1982 (Orion Nebula). 19 NGC 2168 (M35) and NGC 2158. 21 NGC 2287 (M41) . 23 NGC 2392 (Eskimo or Clown Face Nebula) . 23 NGC 2422 (M47), NGC 2437 (M46), and NGC 2438 . 24 NGC 2437 . 26 ix x Contents NGC 2451 . 26 NGC 2632 (M44, Praesepe, Beehive Cluster) . 27 NGC 3201 . 28 InterestingDeepSkyObjects...................................... 29 NGC 205 (M110) . 29 NGC221(M32).............................................. 29 NGC752.................................................... 29 NGC 1291 . 30 NGC 1501 (Blue Oyster Nebula) . 30 NGC 1662 (Klingon Battlecruiser Cluster) . 31 NGC 1973, 1975 and 1977 (Running Man Nebula) . 31 NGC 2169 (The 37 Cluster) . 32 NGC 2237-9, 2244 and 2246 (Rosette Nebula) . 33 NGC 2264 (Cone Nebula, Christmas Tree Cluster) . 34 NGC 2323 (M50) . 34 NGC 2353 . 35 NGC 2360 . 35 NGC 2440 . 35 NGC 2447 (M93, Butterfly Cluster) . 36 NGC 2477 . 37 NGC 2527 . 37 NGC 2539 . 37 NGC 2548 (M48) . 37 NGC 2682 (M67) . 38 NGC 3132 (Southern Ring Nebula) . 38 NGC 3242 (Ghost of Jupiter Nebula) . 39 NGC 3228 . 40 NGC 4590 (M68) . 40 NGC 7662 (Blue Snowball Nebula) . 41 NGC 7686 . 42 ObscureandChallengingDeepSkyObjects......................... 42 NGC404(Mirach’sGhost)..................................... 42 NGC891.................................................... 42 NGC 1232 . 43 NGC 1788 . 43 NGC 1851 . 44 NGC 1904 (M79) . 44 NGC 1981 . 45 NGC 2022 . 45 NGC 2024 (Flame Nebula) . 46 NGC 2194 . 46 NGC 2232 . 46 NGC 2251 . 47 NGC 2261 (Hubble’s Variable Nebula) . 47 NGC 2301 . 48 Contents xi NGC 2343 (Seagull Nebula) . 48 NGC 2359 (Thor’s Helmet) . 48 NGC 2362 . 49 NGC 2371 and 2372 . 49 NGC 2403 . 50 NGC 2419 (Intergalactic Tramp) . 50 NGC 2506 . 51 NGC 2547 . ..