The ability to observe the wonders of the universe is surely one of the greatest gifts from science to the layman. Much sophisticated equipment, once available only to the professional astronomer, has slowly entered the amateur's realm, and today the inclusion of advanced CCD technology has further revolutionized the possibilities. In seasoned and skilled hands, CCD equipment, along with an array of high quality telescopes, has made exquisite photographic images possible which equal or even surpass many great observatory photographs, even of the recent past. However, this leaves me thirsting all the more to see for myself, in real time, as many of those same sights as possible; there is still no substitute for the moment itself. With the exception of the Solar System, what we witness is not likely to equal, or even approach, the incredible wealth of detail, brightness and resolution that modern imaging technology has brought about. However, the eye's and mind's unique response to faint light sources still separates it from any other. All we need is to have visual access to these objects. In my own quest to have a connection with places viewed across time and space, the telescope is my spaceship, but its flights are potentially grounded within city limits by the challenges of observing from such an environment; many amateurs have given up and work only from remote dark sky sites. Indeed, for many, this has been a standard practice for years.
The primary aim of this book is to aid in the pursuit of exceptional live viewing, and from our own suburban environment. In the vicinity of the city, light and
air pollution are our largest problems; urban humidity only adds to the lack of atmospheric transparency. From these sites, deep space viewing doesn't seem a remotely realistic proposition, let alone anything that could be described as spectacular. Suburban viewers are usually limited to glimpsing only the brightest Messier objects. We must face the dilemma: a lack of opportunity to pursue astronomy with a frequency equal to the passion. One remedy has been to use binoculars or richest-field telescopes to see some of the larger and brighter objects to greater satisfaction, but this is not the direction I wanted to pursue for this book. While binoculars provide a highly valid and enlightening approach, there is only so much access to deep space objects one can gain this way. I wanted to find whatever ways I could, with my telescope, to access at least some of what can be seen from remote dark sky sites, but from my home base. As it turned out, with the investment in some additional equipment, there is actually much you can see with your telescope in the suburbs. The results can be spectacular indeed! Of course, we should take every opportunity possible visit ideal locations, and look for the best conditions, but what about the rest of the time? Since my own text is designed as an attempt to reveal what can be achieved in far less than optimal (sometimes very much less than optimal!) circumstances, it is my hope that true suburban backyard astronomy may again become a reality for you. Therefore, if the occasional, or even frequent trip to an ideal dark sky site is enough for you, this book is probably not for you. However, I still invite you to read on and would hope you will enjoy its pages and ponder some other possibilities.
Of the two primary sky pollutants, light is the most troubling, and affects us mostly as a perpetual twilight that washes away the stars. This topic is rapidly becoming a cause célèbre around the world; you are probably already well aware of it, and many young people today have never experienced the awesome presence of the firmament under a truly dark sky. It is getting increasingly hard to escape the glow of some urban area, almost no matter where we live. Most of us simply do not have the time needed to drag our equipment to a better location whenever the bug bites us; for me, an occasional trip to the mountains just isn't enough to sustain the fire. As increasingly large segments of our populations become occupants of cities, or areas near cities, it is apparent that these hubs of civilization are becoming increasingly hostile places to look toward the stars, as they infect the night sky for countless miles around. In addition to light and atmospheric pollutions, the low elevations of most urban centers necessitate peering through the thickest and most turbulent layers of the atmosphere as well. Coupled with this, every city-dwelling observer has to contend with the frequent hazard of high buildings and obstacles, which restrict the viewable sky, leaving the horizon seldom visible. (I still do not have a remedy for this particular problem!)
For most people, the old-fashioned notion of observing the heavens the old-fashioned way, with one's own eyes, seems to be headed for extinction. However, it is possible to preserve much of this ideal through carefully applying the best that technology has to offer. I therefore approach observational astronomy with a somewhat different slant to the thrust of most textbooks today. I do not set out to show what can be done in great conditions and locations. Certainly you won't find in these pages a source of the usual sky charts, facts and figures common to so much available literature. I also don't try to espouse all the latest releases in astronomical software, which seem often to relegate actual observing to secondary importance. Finally, I certainly didn't set out to create yet another slick, gaudily colored, graphics-saturated volume of the type so common today; I often wonder if many publishers assume we have all lost our imaginations and intelligence!
Visual Astronomy in the Suburbs is intended to be used along with access to other reference sources, and at least a good celestial atlas. As a reference source, I strongly recommend Burnham's Celestial Handbook, Volumes 1-3 (see Bibliography) as your primary resource of detailed information. There are, of course, other materials available, including software resources, but in my opinion, Burnham's is still hard to beat. (How did just one man compile such an epic in his spare time?) Its remarkable wealth of information and infectious enthusiasm will complete or supplement the background that this volume does not set out to do. Although Burnham's is aimed at users of telescopes of up to 12 inches, the limitations imposed by our suburban environments make many of Burnham's listings of celestial sights impossible to see effectively (or even at all) when using substantially larger apertures than 12 inches. Because of this, you can easily be assured that you will not run out of sights to explore listed within its pages. Meanwhile, relegated to suburban viewing:
(i) What can be done to combat the difficulties of pursuing real time astronomy around our population centers, and to what extent?
(ii) Of countless sights in the sky, which of them can we realistically expect to provide spectacular viewing?
(iii) What measures can we take, what can we reasonably expect to see, and how will these sights actually look to us?
(iv) How can we best share and record our real time viewing, without the need for elaborate time-exposure imaging?
Almost all of the many fine books on practical astronomy for amateurs seem to make one assumption -ideal, or near ideal viewing conditions. Photographs and drawings by skilled individuals, in superlative situations, are presented to us. Often, the colors and detail represented by these images would no doubt lead the suburban novice to anticipate such views, live, through a newly purchased telescope. Now, the makers of many popular models of telescopes and accessories aren't in the business of educating the public about the challenges facing the would-be amateur astronomer. Also, the large boxes in which these scopes are packed (and even the ads touting them) often feature magnificent pictures of celestial sights, presenting an entirely false expectation to the uninitiated. Most of these unsuspecting souls must have a vision that they merely have to cart their shiny new scope outside, aim it, and see multitudes of heavenly wonders glowing brilliantly in the field of view. Such views aren't the case even at an ideal site! Is it any surprise, then, that for most people, a budding interest in astronomy soon wanes after the purchase of their first "department store" telescope? Add to this the simple fact that these cheap, but not inexpensive instruments aren't good for much in the first place.
More remarkable to me still are the sales of bettergrade telescopes, equipped with on-board sophisticated controls, featuring thousands upon thousands of pre-set objects and even automated object location ("Go To" scopes) - whiz-bang gizmos to be sure. There is only one problem - their apertures typically aren't sufficient to show most of these wonders with any degree of satisfaction to their uninitiated new owners. This is even more certainly the case in the suburban locations in which they will likely be used. In most cases, the vast majority of these objects will be completely invisible! Most of their uninitiated users haven't even heard of "dark sky sites".
Some die-hards will tell you that visual astronomy from the city boils down to viewing only the Moon and planets. Since the Solar System is a major area of interest to me, and it provides a significant part of this writing, you can take it that I don't intend to minimize its significance for us in suburbia. It is also the one area of practical backyard astronomy that can be successfully carried out from the suburbs without any special provisions being taken. Admittedly, we may have fewer nights of steady air than a high altitude site, but there is no reason not to expect some first-class results from our suburban lairs. However, though there is much pleasure in the study of these subjects alone (some do it exclusively), most of us will ultimately want more, since we know it is there; it is only one part of the whole. Deep space, the true realm of the universe, beckons. To this end, if we live towards the edges of the city in more rural locations, things indeed do become more promising as the glow in the sky diminishes. Ultimately, however, some degree of the same limitations imposed on us by city life becomes a factor again in our consciousness; we know we are missing something, even though such a semi-rural viewing site might be a dream come true for the suburban or urban observer. Reluctantly, it must be acknowledged that even in these improved surroundings much potential for good viewing is lost, and for the same reasons. Therefore, I hope the direction of this writing will even be of interest to these somewhat better situated stargazers as well; they may actually have the greatest promise amongst us for radical improvements in their own viewing.
In order to be successful in your pursuit, I will assume that you possess an appropriate telescope for your surroundings. Nobody can tell you exactly what that should be, though the maximum aperture - of quality and practicality - should always be your strongest single goal. Dobsonian telescopes have certainly illustrated this concept wisely: bare bones, optical dimensions forefront. We have to recognize that different conditions and apertures at any given site will affect what can be seen and how well. (Where I live the bright light of the suburbs and frequent hazy conditions often will not permit some faint objects to show in my own 18-inch, which a good 6-inch in much better conditions will reveal. However, the 18-inch's resolution on any visible object naturally will still be superior.) I should stress that for deep space observing there is absolutely no basis to the enduring myth that a small aperture outperforms a large one in the type of sky conditions that this writing addresses. The larger aperture will always outperform the smaller. It is said that such apertures only amplify skyglow. This is true, but they also amplify the light source we are looking at! The large aperture can also handle significantly higher magnifications on these subjects without losing them in the background sky, and these higher powers will sometimes work to our advantage when detecting many faint objects, by throwing the background into deeper contrast.
So while I firmly encourage you to buy the largest telescope you can afford and use practically, be aware that a downside of the greater sizes will be their increasing negative reaction to unstable air, and the need for more time to cool down to nighttime temperatures. Fortunately, many of the problems we face from air currents and temperature changes only become serious issues at higher powers, and much of deep space viewing will be at its best with lower powers. It is also true that once the amateur observer has access to a moderately large telescope, say, 12 inches aperture and more, the differences with even sizeable professional observatory instruments are not nearly as drastic in unaided real time viewing as one might suppose, given equal viewing conditions.
Here are some general principles in regard to viewing conditions and our suburban environment:
• Haze and thin fog are not necessarily bad for lunar and planetary viewing. If these conditions result from stable and still air, the "seeing" may indeed be pretty good. The haze will sometimes reduce glare and act as a filter on these subjects. Viewing them is just as effectively realized from areas of great light pollution, and even bright nearby lights! All in all, they remain a suburban gold mine for us.
• These same conditions are ruinous for deep space, however. A good rule of thumb is to save your galaxy-hopping for the most transparent skies you are likely to have. They respond best to the clearest air; steadiness (the state of "seeing") is not nearly so important as it is for the planets and Moon. Total surface brightness for all deep space objects is a key; the suburbs render more difficult spread-out objects of high total magnitudes.
• Planetary and emission nebulae have an amazing tolerance to less than ideal air, and even though a perfect sky would be best, they can still put on a surprisingly good show in poor conditions.
• Reflection nebulae again need clear air to be at their best, as increasing haziness may obscure them completely.
• Star clusters will do better than most subjects in less than perfect sky, though naturally, transparency is always preferable. This is quite apparent in their ability to appear spectacular and to reveal any dark lanes.
• In my own location (Southern California), I have found that air currents moving off the sea onto the land are usually far more damaging to "seeing" than the reverse. Often a mild "Santa Ana" wind condition off the deserts brings the best "seeing" for lunar and planetary observing, as well as the clearest air. Viewing the Solar System at these times is sometimes breathtaking.
By my own definition, I chose to take the maximum "big gun" approach to the equipment dilemma, but bear in mind that my own location, astronomically speaking, is about as bad as it could be, despite the seeming endless blue skies of Southern California. It is well known that light and atmospheric pollution are already the norm in Southern California, which certainly makes deep sky observing anywhere near our population centers a major challenge. This has only become worse over the years. To compound matters, I live on a cliff-top at the ocean, with the resulting increase in humidity, haze, frequent night-time marine layer, and destabilizing ocean breezes; living here has necessitated some compromise for astronomical purposes. But since astronomy in most locations closer to the city hub (Los Angeles), would not necessarily be more effective, the only other alternative would have been to allow astronomy to rule all my life decisions and live out in the desert, far away from civilization! Nevertheless, through the addition of some of today's technologies (see Chapter 2), which give us a new lease on astronomical life in the suburbs, I am enjoying some wonderful viewing, in conditions that I am sure are substantially worse than most stargazers ever have to deal with. I am confident that equal, if not even superior, results can be obtained by much less means in less hostile skies. (It is true that over the ocean, light pollution does slowly drop toward the horizon - but near the horizon, haze is usually at a maximum! ) I do, however, enjoy an uninterrupted view of most of the sky, and over the water, a totally unobscured view. This is indeed something of a bonus, particularly in viewing some of the Southern Hemisphere objects which are visible to us in the Northern Hemisphere.
Aside from our physical location, we also have to learn to see all that is present in the telescope image, if we are to be effective as astronomical observers. This is the subject of Chapter 3, and the need for it is true also even in the best of circumstances. It is all the more important in areas of viewing difficulties such as ours, where we are trying to extract the maximum results from the viewing situation. Looking through a telescope is not like looking at a picture on the wall, or television, much less the type of lavishly illustrated book on astronomy that we are all so accustomed to seeing. It is anything but the passive pointing of our telescopes and simply seeing what is there. The atmosphere is usually in a constant state of motion, more often instability. The light level of the objects we wish to observe, even under ideal circumstances, is low; the tiny scraps of light we are receiving is all that is reaching us from these extraordinarily remote places. City air, and especially light pollution, become critical if this is where we must observe most of the time. Since we are looking for details which are at the very limits of visibility, our eyes also need whatever degree of dark adaptation is possible, something made all the more difficult by nearby direct city lights. With patience and enough enthusiasm-driven commitment, we can acquire seeing skills; even then, we will still need some key technology.
Chapter 4 is concerned with techniques and methods we can use for recording what we see as it appears in real time. Hopefully it will furnish you with the means to expand the range of real time observing experience, and to share it with others. In addition to the chapters on the Moon (Chapter 5) and Planets (Chapter 6), I have devoted the largest portion of this writing to that almost lost denizen of the city dweller - deep space observing. Chapter 7 features a catalog and descriptions of the most successfully realized deep space objects for suburban dwellers known to me. Some of these may already be familiar to you as Messier and other objects, their inclusion probably not unexpected. More surprising to you may be those well-known objects (including many of Messier's) that do not make the list. Many of them are unsuccessful to view in the suburban environment; some have always been successful as binocular objects only, and this is not a book centered around binocular astronomy. Possibly most interesting will be those objects not so familiar to amateur observers. Here, also as in Chapters 5, 6, I have endeavored to provide very real visual impressions of what you may actually expect to see in typical suburban conditions for all those objects I describe.
In the approaches to observing in the standard literature and guidance available, it seems to me that disappointment is virtually guaranteed for any newcomer who is largely confined to the city. Aside from a suitable telescope, most of the objects in Chapters 7, 8 and 9 generally require the accessories alluded to already, along with which they may be successfully observed. The visual impressions and images included within the text are necessarily confined to those objects visible from my own latitude - in fact, a remarkable percentage of the total. Hopefully, in Chapter 7 these real time images will illustrate the essence of what you may expect to see, when viewing each of these objects. They attempt to convey something of the real time experience itself, and generally consist of live video images and/or drawings. (I should still emphasize, however, that there is simply no way to substitute a picture in any form, or a view on any monitor, equal to the live view through the telescope; this remains in its own realm.) Where it was not possible to include a video image (as opposed to a drawing), it was because the particular object does not respond favorably to such imaging, or is negatively impacted by my own circumstances. Maybe the relatively high minimum powers my telescope imposes made only a drawing possible, because of the much reduced field of view of the image intensifier (my lowest power regular eyepiece has a far wider field of view). Still in other situations, a drawing creates an entirely false impression. Star clusters are such items. For the most part, the eye is not better prepared by studying drawings of these objects. I have yet to see an illustration that actually looks anything like one, at least as far as conveying the visual appearance is concerned. Often complex structures are drawn that seem to have no resemblance to anything I have ever seen, while missing features that I have seen or recorded by video camera. However, for most deep space objects, I have been able to include both forms of image. I hope the reader will gain the most complete expectation possible from the examples. This is obviously a moving target, depending on a combination of your own circumstances and equipment, but I believe the illustrations I have selected for each object will more properly prepare you for what you are likely to see from the suburbs than most other materials you can find. A large proportion of the objects totaling the listings of all three chapters will be visible from both Northern and Southern Hemispheres, and at many latitudes.
The sights of Chapter 7 have also been carefully chosen to give the backyard astronomer a catalog of objects throughout the year likely to delight visitors. How often are these often unfortunate people (our victims?!) left wondering what we get so excited about, while we fumble about trying to find a successful view of something - anything! Either that, or we resort to the same old tried and tested meager handful of "sure things", in the hope we can convince our visitor(s) that "they're all like that!"
The full extent of any deep space object will likely be seen only in time-exposed images. Some mental adjustments will have to be made in order to know what you are seeing when it comes to viewing them live. You should study as many observatory and CCD images of these objects as possible in advance, so by the time you compare what a quality exposure of a given subject reveals, you will make out more from the real time view, and the experience becomes all the more satisfying. Tiny pieces of faint detail assume great significance when you know what they represent in their veiled suggestion. Where an image I provide seems ambiguous (in showing whatever I could witness or capture), I also include a graphic with the object's fuller extensions indicated, so it will make more sense.
Common sense also tells us it is not only improvements in optical technology since Lord Rosse's time which make it no longer necessary to have a 72-inch aperture to see spiral structure in galaxies; more significantly, it is also because we know the spiral structure is there. But here is a critical caveat: we must strive to keep our eyes "honest" and not to let their "education" fool us into believing we are seeing something which we actually are not. (The "canals" of Mars are amongst the best known examples of this.) Conversely, drawings of planets made before the era of space exploration are remarkably different in character to drawings made today. This serves as one of the best lessons for us in "eye education". In addition, it is routine now to see details, and above all, to have overall impressions that were often never even mentioned in the past; through the telescope our impressions can be forever changed once we know what to look for. Since the advent of spacecraft and CCD imaging, I also don't believe that it is only due to three decades of relative calm on Mars and Jupiter that there seems to be a remarkable degree of "stability" on the surfaces of both of these worlds! I believe that at least some of this may again be due to our eyes becoming more accustomed to knowing what is really there.
Chapter 8 features my own carefully screened secondary catalog of other deep space objects definitely worth taking the trouble to look for, along with certain relevant information, and illustrations of many of the best examples. They are within reach from many suburban locations. Depending on your own location and viewing conditions, they may even become part of your own personal best list. For me, my own viewing circumstances do not quite allow them inclusion in the "best sights" catalog of Chapter 7, and my primary interest lies with objects that reveal themselves as more than just a blip or smudge in the field of view. I will admit that a few were a close call, but for better or worse, they were relegated to Chapter 8. Both listings (Chapters 7 and 8) represent objects, compiled from my location, which should be possible to view in suburban conditions, the first list (in Chapter 7) being the most likely to be in the realm of the spectacular. And of course, many of these same objects are visible to observers in the Southern Hemisphere. I have excluded whatever I feel will more than likely lead to disappointment and frustration rather than success. The listing in Chapter 9 completes the survey for viewers living in the Southern Hemisphere, and features a supplementary catalog of outstanding objects of the South, from the same standpoint of suburban viewing. It was not possible to include comparable depth of information on these objects, or images of them, but by the limited size of this final catalog observers in both hemispheres will realize just how much of the total sky can be seen from each.
The objects listed in Chapters 7, 8 and 9 have been arranged in the order that they progress across the celestial sphere; these catalogs are not so large as to make it unwieldy. To any observer using this book as a reference, this is designed to be more useful and practical than arranging them in alphabetical sequence. Alphabetical listing would require constant thumbing back and forth through the pages, when objects relatively near to each other in the sky could be accessed at the same time more easily by grouping them according to right ascension. I believe practical observers will find this system preferable in this particular instance.
Chapter 10 raises a few final comments and thoughts. The appendices list some of the more prominent manufacturers and suppliers of equipment relevant to this writing, along with some approximate cost guides, technical information, and other commentary.
Regarding many of the better-known "binocular" items, many do indeed appear on the second list, especially open star clusters. Through a telescope's much more limited field of view, these are often too spread out or faint to be impressive in the sense that Chapter 7 was compiled. This factor is compounded by increasing aperture (and hence typically shrinking field of view), though depending on your own circumstances and telescope, you may wish to add some of them to your personal "best" list if they turn out to warrant inclusion. In my opinion, though, most of the globular clusters simply outclass the open clusters anyway, when it comes to seeking out the absolute best that the sky has to offer, and unsurprisingly, some of the finest examples of these feature quite prominently in Chapter 7.
I am leaving alone the subjects of double and variable stars. They certainly represent a major part of astronomical interest and study for many people, but in my view, they do not represent the spirit or intention of this writing. However, I am sure some viewers might include them in the realm of the spectacular; maybe they are. You must determine this for yourself, but please forgive any apparent lack of acknowledgement that I may imply. At least many doubles and variables present few observing problems to the suburban dweller, and no special means to combat the problems common to other deep space objects may be necessary for successful observing programs. As major areas of study, doubles and variables are best left to the litera-
ture that covers the field, and would not be served appropriately by the approaches discussed here. If your interests extend to meteors, asteroids, occultations, comets and novae, they are all certainly within the realm of suburban viewing, especially when incorporating what this book outlines. Nevertheless they are outside the scope or intention of this writing; at times however, comets and novae are indeed capable of providing us sights that could be described as nothing less than spectacular, and as impressive as anything else contained here. At such times, you may wish to experiment with the same approaches discussed here, and your results may indeed be memorable. However, unless you are a hunter of these phenomenon, you will need to access monthly magazines and Internet sites, such as International Supernovae Network, if you want to find them without the enormous research and investment of time they will otherwise demand.
I am also leaving the observation of the Sun untouched. I do not venture towards it because I have not made a direct study of it, partially out of fear of the consequences of error or equipment failure! Even using one of the excellent solar filters available today, I am all too aware that this is the only thing between my eyes and the staggering solar blast that would be reflected off 18 inches of aperture in the event of failure. I simply cannot overcome my natural distrust to any such filter, wedge or the like, in spite of all the evidence of their safe usage. Projected solar images would be out of the question, with the furnace that the large aluminized surface of my scope would generate. A normal practice is to substitute an unaluminized primary for the purpose, but this naturally limits the objective's use to solar observing only, and it is not a practical option in larger sizes to have two objectives. In any event, since solar observing is a whole field of study by itself, I will leave it to others to guide you if this is a field that is of interest. Certainly its application is undiminished in the suburbs, but do not undertake it lightly; your equipment and expertise cannot fail you.
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