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This chapter introduces some of the general guidelines for starting an observing program for faint objects. The objects featured in this book are mostly those that need a telescope with an aperture of 10 in. (25.4 cm) or more, observing in relatively dark to very dark skies. One may also use these techniques to observe somewhat brighter objects from light-polluted locations or with smaller instruments. What is common for both setups is that one is looking for something that lies at or near the edge of visibility and that person is trying to get the most out of the observation.

Galaxies are huge collections of stars and vast amounts of gas and dust and are found throughout the known universe. Galaxies outside our own are so far away that the stars blend together into an amorphous haze, and some of the dust (in larger concentrations) is visible in silhouette against the bright material (e.g., the dust lane of the Andromeda and Sombrero galaxies). They come in various morphologies and are categorized into four groups based on their appearance in the sky: ellipticals, spirals, barred spirals, and irregulars. They can contain as few as tens of millions of stars but as many as hundreds of trillions of stars.

There is literally a universe of objects competing (unbeknownst to the objects themselves, of course) for your attention at the eyepiece, and one question that you may be asking is: Where do I get started? This depends on what type(s) of object(s) you are interested in viewing and what your experience level is. Do you want to view only a small sampling of objects or do you like the challenge and satisfaction of long observing lists? What is the size and capability of your telescope, and what type of dark site do you have access to? These should all be taken into consideration when outlining an observing program.

There are plenty of opportunities for everyday citizens to contribute to the science of astronomy while searching for faint objects. The observing lists and information presented up to this point outline how you can get started and keep with the program of observing faint objects from a more recreational perspective. Although there is indeed much value in pursuing objects in that capacity, one can also go farther in one’s pursuits if one wants to join the ranks of citizen scientists all over the world who are contributing in real and valuable ways to the science while pursuing their favorite hobby. If this describes you, then the following sections will be useful for you to expand your astronomical significance.

Let’s take a look at some of the “starships” of our time, facilities that have given us the deepest views of the universe ever seen by humankind. The “starships” referred to here are the largest ground-based telescopes, the Hubble Space Telescope, and the other three members of NASA’s “Great Observatories” (Spitzer Infrared Space Telescope, Chandra X-ray Observatory, Compton Gamma Ray Observatory), all of which have given us our deepest views of the universe yet. They are called “starships” because of their ability to “take” us to these distant places through extreme imaging, either looking out in wavelengths invisible to the human eye or collecting sparse amounts of photons over (for example) a 30-h period to reveal the most distant galaxies that would otherwise be invisible.

Astronomy is the oldest of the physical sciences and can be traced back to antiquity or at least 5,000 years ago [1]. Looking that far back in time, we see the origins of astronomy mixed in with the religious and astrological practices of pre-history. Ancient societies were already able to tell the wandering planets from the “fixed stars” and associated these moving objects with gods and spirits. Various cultures have practiced various religions related to astronomy, with the priests playing the role of the “professional astronomer” of their time, and demonstrating a “divine” understanding of the movements of the heavens. So it seems that the first few millennia of astronomical involvement of human societies were religious in nature.

One of the essentials of faint object observing is a dark sky observing site [89]. This can be a site that is owned or leased by your local astronomy club. The author uses a location that is simply referred to as “The Dark Site,” an 18 acre piece of land some 7 miles west of Columbus, Texas, which is managed by the Houston Astronomical Society for the use of its members and guests (a family who is well known in the greater Houston area owns the property as of this writing). Other clubs may or may not have dark sites of their own. The preferred site is one that is owned or operated by someone you know (and you have permission to use their land), or is a site where a “star party” is held annually or more frequently. Annual star party events such as the Texas Star Party are excellent venues for observing faint objects. Don’t just pick an arbitrary field without knowing who it belongs to or what it is – remember, SAFETY FIRST.

In addition to the “normal” deep sky objects featured in the observing lists offered in Chap. 10, some of the brighter members of exotic objects, such as blazars, quasars, BL Lacertae (Lac) objects and others are also featured [73]. These include a handful of examples of gravitationally lensed objects such as the Ursa Major double quasar and “Einstein’s Cross.” An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much higher than normal luminosity over part or all of the electromagnetic spectrum. A galaxy that hosts an AGN is termed an active galaxy. The radiation that comes from an AGN is thought to result from the accretion of mass by the central supermassive black hole.

What follows is a brief historical narrative of some of the more important figures in the history of deep sky astronomy during the age of the telescope. Far from being a complete listing, the following does highlight some of the important figures involved in expanding our view of the universe. Once the telescope was invented and accepted as a useful scientific instrument, along with improvements in the optics of both reflectors and refractors, it became possible for various astronomers to carry out systematic surveys of the nighttime sky, cataloging the various objects they encountered along the way.

In the last chapter was an overview of the variety of projects that are out there that one can use to get started, and keep going, as far as observing faint objects is concerned. In this chapter, we provide a group of projects containing 721 individual objects (including four groups of galaxies, eleven pairs of galaxies, and ten clusters of galaxies). These lists are provided in the form of 16 tables, each grouping containing information on various deep sky objects according to object type and where they are found (in the Milky Way, in the Andromeda Galaxy, in other galaxies, etc.). Each table represents a separate observing project, although some tables (such as Tables 10.1, 10.6, 10.14, and 10.15) are quite long, with many entries to keep one busy for a while. There are certainly enough objects listed here, collected from a variety of sources (and with references to more lists related to these and presented in Appendix E of this book), to keep the serious visual amateur hunting for faint objects for years to come.

The next few chapters provide a basic “Astronomy 101” introduction to the types of objects that will be looked at later in this book (and you will look at later through your telescope). We are focusing on faint objects outside the local Solar System; information about faint planets, comets, and asteroids can be found in books written about these classes of objects. Our focus is on objects that can be found throughout interstellar space, along with objects found beyond our very own galaxy to the edge of the known and visible universe. But first here are some basics on the main kinds of deep sky objects that we know of.

This chapter presents a catalog of documented events on the Moon likely (or possibly) resembling impact phenomena. These events are referred to by the author as possible impact phenomena (PIPs).The catalog was assembled from several different sources, listed later, and is divided into sections by century, beginning with the twelfth century. Naturally as one approaches the present day, the number of reported events seems to rise exponentially as the number of observers, as well as the efficiency of the methods of observations, increases. For example, in the entire seventeenth century, two events were recorded compared with 19 during the 1950s.

As discussed in the Introduction, the Leonid meteor shower of 18 November 1999 produced the first independently confirmed observations and recordings of meteor impacts on the Moon. A number of attempts have been made previously to observe and document lunar meteor impacts, but none have produced scientifically confirmed observations from two or more widely separate (more than a few tens of kilometers or miles) locations. Some of these efforts have met with some success, with a number of probable events recorded. The uncertain and unpredictable nature of this phenomenon, along with insufficient camera sensitivity to record all but the largest events and the difficulty of visually locating very short flashes in the midst of hours of data, has led to its very limited success. With new technologies and techniques, the question has shifted from “Does it happen?” to “How Many?” and “How Big?” The program that follows observations of lunar meteor impacts is characterized by long periods of little activity, punctuated by very brief flashes or clusters of activity.

In addition to the guide (Chapter 9) which shows how to observe impacts as they happen, I provide in this chapter a brief guide for observing existing lunar impact features. Although the impacts observed using ground-based telescopes produce craters that are much smaller than what can be observed through a typical backyard telescope, one can observe their much larger cousins and consider how an impact that resulted in that crater may have looked from the Earth.

This chapter provides techniques and tips to maximize the chances of obtaining successful observations of lunar meteoritic phenomena. The chapter is divided into four broad sections: general guidelines for observations, techniques for visual observations, techniques for video observations, and highlights of useful equipment and observer setups to guide the novice (and even enlighten the advanced) in the observing process. The two latter sections include a number of elements that have been brought together from dialogues and discussions among members of the IOTA group over several years’ time as well as my own experiences along the way. The members have, over the years, discussed in detail a number of pieces of equipment and their uses in the field of stellar occultation observation, most of which can also be used in the recording of lunar meteoritic impact flashes. However, due to the stringent time requirements inherent to occultation timing observations, a number of items related to equipment and techniques are not applicable in the area of lunar meteoritic observations and have been omitted from this work. Nonetheless, the same equipment used in occultation observation can also be used in the observation of lunar meteoritic impact events. Steve Preston of IOTA provided a tutorial on extracting event times of stellar and lunar occultations (and lunar meteor impacts) from videotape; this tutorial is presented in Appendix C.

The Moon is an airless body, devoid of the atmosphere that Earth has to protect it from the impacts of meteoroids. In the case of the Earth, the atmosphere shields the ground from all but the larger (and much rarer) meteoroid collisions. We see the collision between the meteoroid and the atmosphere as a “falling” or “shooting” star, sometimes leaving a brief luminous trail of ions in the atmosphere. On the Moon, where there is no air, any meteoroids collide directly with the lunar surface, without being slowed by air. Over the age of the Solar System, meteoroids and asteroids of all sizes impacted the Moon and other celestial bodies, producing the pockmarks that we know as craters. It was not until the middle of the twentieth century that craters on the Moon were found to be a result of the impact. Also, it was not until the advent of spacecraft exploration that craters were found on other worlds, such as Mars and Mercury.

One of the active groups involved in lunar meteoritic impact research is the Geological Lunar Research (GLR) of Italy. Working in conjunction with the American Lunar Society, they have assembled an online manual that provides guidance on how to make successful observations of lunar meteor impact events. (The complete copy of the manual is available, as of October 2008, for download at the following web address: http://www.glrgroup.org/lunarimpact/manual.htm) In their case, the manual emphasizes the detection and mitigation of spurious flashes and offers solutions on how to distinguish true impact candidates from cosmic ray flashes. The spurious flashes segment of their manual is reproduced, with permission, below.

We now look beyond the Earth–Moon system to see how impacts are shaped throughout the Solar System.8,9 In Chapter 1, I gave a brief overview of worlds (in the form of images) showing how widespread cratering is from Mercury to Triton, and related this to the most widely accepted theory of the evolution and development of the Solar System. We also saw how this evidence provides clues into the evolution of our local planetary system to its present form. We saw how a huge impact likely led to the formation of the Moon and how impacts shaped the surfaces of the worlds in the early history of the Solar System. Impacts are also considered to be responsible for the retrograde (backwards) rotation of Venus, the high metal content in Mercury, the dichotomy in landforms on Mars, the rings of Saturn, and the extreme axial tilt of Uranus. One of the moons of Uranus, Miranda, appears to have been broken up by a large impact, but something unusual happened after the impact: the object pulled itself together again to become one body.

Up to this point, for the most part, we looked at lunar meteor impact observing from an amateur astronomer’s perspective. We also surveyed the products of meteoroid impacts – craters – on the Moon and throughout the solar system. Background information of these, as well as observing techniques, has been presented. This chapter changes the focus a bit, brings in a little professional perspective, and discusses how amateurs and professionals can work together to make a significant contribution to lunar impact research.