Deep Sky Observer's Guide - Softcover

Bone, Neil

Softcover

ISBN 10: 1554070244 ISBN 13: 9781554070244

Publisher: Firefly Books, 2005

Synopsis

'Deep Sky' refers to the universe beyond our own solar system. Using binoculars or telescopes, any sky-gazer can become a deep sky observer. Deep Sky Observer's Guide looks beyond individual stars to target:

• Star clusters
• Double Stars
• Nebulae
• Galaxies.

The Deep Sky Observer's Guide introduces the basics of observing and explains what equipment is required. A chapter is devoted to each type of deep sky target. There are more than 200 such objects featured, with 126 color illustrations and star-finder charts.

The Deep Sky Observer Guide is also available in a convenient pack (ISBN: 1-55407-025-2) that comes with deep sky charts and an observing calendar.

About this title

About the Author

Neil Bone is a frequent lecturer for astronomical societies.

Wil Tirion is the world's foremost celestial cartographer.

Excerpt. © Reprinted by permission. All rights reserved.

Chapter 1: Introducing the Deep Sky

Astronomy is surely the most visual of the sciences, and this is largely why it has so captured the public imagination. Television news reports and the daily papers often carry the latest images from space exploration. Pictures of Mars, for example, were prominent on the front pages in August 2003, during the Red Planet's closest approach for 60,000 years, followed by extensive media coverage of the Spirit and Opportunity rover landings in early 2004. Of the great many images from the orbiting Hubble Space Telescope (HST) to have entered the public domain, perhaps none enjoys more lingering iconic status than that of the Eagle Nebula, released in 1995. The HST's clear view from above the Earth's distorting atmosphere revealed the nebula in unprecedented detail. The nebula's "Pillars of Creation" -- long fingers of dark dust tipped by newly formed stars -- have become as familiar as the Voyager images of the outer planets.

The Eagle Nebula is found in the constellation of Serpens, just north of the richest parts of the Milky Way in Sagittarius and Scorpius. While it can never be seen in such fine detail through a typical amateur astronomer's telescope as it was by the HST's sophisticated instrumentation, the Eagle Nebula (also known as M16) is a familiar sight for many whose passion is observing the deep sky.

Quite when and where the term "deep sky" came into widespread use is unclear. It has certainly been used at least since the late 1960s as an umbrella description for objects far beyond the bounds of the Solar System. As an activity for amateur astronomers, deep sky observing has often been regarded as more of a pastime than an exercise in obtaining potentially useful scientific data, such as brightness estimates for variable stars, meteor counts, or details of changes in Jupiter's cloud belts. It does remain a largely recreational activity: amateurs' telescopic observations are never going to add new objects to the existing catalogs, for example, though it was notably an amateur observer who in early 2004 first detected a new bright patch, which soon became known as McNeil's Nebula, in the reflection nebula M78 in Orion (the "M" number is the nebula's designation in the best-known listing, or catalog, of deep sky objects). There is, however, a large and growing band of observers who take their deep sky studies a little more seriously, using faint, hard-to-find objects as a test of telescope performance, visual acuity and ability to navigate around the night sky.

Skills acquired by the experienced deep sky observer are applicable to other fields of astronomy. Perhaps most obviously, hunting out faint comets -- in appearance, "mobile nebulae" -- demands exactly the same skills as finding faint deep sky objects.

Discoveries in the CCD age

While extensive sky surveys have long since swept up all the amateur-detectable deep sky objects, discoveries remain to be made. Some dedicated deep sky enthusiasts have established observing programs to search for supernova explosions in distant galaxies. Newly discovered supernovae offer professional astronomers valuable insights into the scale and evolution of the Universe, and amateurs carrying out semiautomated searches can help by providing early alerts. Some -- most notably the Rev. Robert Evans in Australia -- have made important supernova discoveries using only visual telescopic searches. Such searches demand a familiarity with the normal appearance of many galaxies if the presence of any new star is to be immediately apparent to the observer. The most prolific amateur supernova discoverers have in recent years used automated telescopes which are capable of rapidly locating upward of 30 galaxies an hour and are equipped with CCD (charge coupled device) cameras that take "patrol" images. The images are later compared with a reference image to check for the presence of potential interloper stars. Mark Armstrong and Tom Boles in the UK have between them discovered well over a hundred supernovae in this way, while searches in the United States by Michael Schwartz, Tim Puckett and others associated with teams such as LOTOSS, guided by professional astronomers at institutions such as the Lowell Observatory, have similarly proved fruitful.

CCD cameras have revolutionized deep sky imaging. Their high sensitivity to light makes them much more efficient than photographic film for recording faint objects, and with many good post-observation image processing programs now available for personal computers, digital imaging is already beginning to replace film as the medium of choice for imaging the deep sky. Whereas traditional deep sky photography often demanded expensive (and, in the case of gas hypersensitization procedures, sometimes dangerous!) pretreatment of the film and long exposure times, CCDs can record more at the touch of a button and in a matter of seconds.

One downside to CCD imaging is the expense of the hardware. When CCD equipment for amateur astronomers first appeared on the market, imaging chips were small and costly. Size is gradually increasing and prices have come down, but setting up to do CCD imaging still demands a sizable outlay: a laptop computer, at the very least, is needed to run the imaging software and store raw data, on top of the cost of the CCD camera itself. In this book I concentrate on visual observing and recording by simple methods. I am quite sure, though, that after an initial visual exploration of the deep sky, some readers will feel encouraged to take their interest further, into the realm of photographic and CCD imaging.

The Visual Deep Sky

At the other end of the observational spectrum, there is absolutely no reason why locating deep sky objects shouldn't be simply a pleasant recreation! In common with many others, I enjoy those occasional crisp, clear nights with a dark sky and a couple of spare hours to spend searching out a nebula, star cluster or galaxy which I have never looked at through a telescope -- or revisiting "old friends" which I may not have seen for a few years. Amateur astronomy is pursued in most cases for the enjoyment and satisfaction it brings, and the observation of interesting deep sky objects should certainly provide both.

Many detailed handbooks and guides have appeared over the years, listing the huge numbers of faint deep sky objects that can be glimpsed through large telescopes (sometimes described crudely as "light buckets"). My aim here, though, is to provide an introduction for observers with smaller instruments. Most of the targets I describe are reasonably bright and easy to find, but I also throw in a few more challenging objects to add to the thrill of the chase. All the objects included in this book should be within the reach of a small 80 to 100 mm aperture refractor or a 150 mm reflector, typical portable instruments owned by the beginning or moderately experienced observer.

Although I have been observing the sky for more than 30 years, I still find it convenient to do much of my occasional deep sky observing with a wide-field 80 mm aperture refractor -- essentially a "spotting scope." It can be set up for observing and packed away afterward in a matter of minutes -- an important consideration at the end of a long working day, or when there is only a little time available for viewing.

Binoculars can give good views of brighter objects and are useful in a number of other areas of practical amateur astronomy -- variable star observing, for example. Even if the observer has access to a small telescope, binoculars are useful for obtaining a low-power view of the field and a first impression of the target. Even quite small instruments, such as 10 X 50 binoculars, will provide observers with their own, first-hand views of the more prominent deep sky objects such as the Eagle Nebula. While they may not reveal the awesome detail of HST images, these instruments offer the satisfaction of seeing things for one

Edition details

• Publisher: Firefly Books
• Publication date: 2005
• ISBN 10: 1554070244
• ISBN 13: 9781554070244
• Binding: Paperback
• Language: English
• Number of pages: 224
• Illustrator: Tirion Wil