HORSEHEAD AND FLAME NEBULAE The Nuts & Bolts of Astrophotography The Nuts & Bolts of ASTROPHOTOGRAPHY ORION AND RUNNING MAN NEBULAE LeRoy Goering
The Nuts and Bolts of Astrophotography Hardware Software & Images LeRoy Goering 1
This effort is dedicated to Wayne my brother, whose love and dedication to parents and family had no limit. When faced with difficulty he always found a way to succeed. His advice was clear and straight forward. Just do it and have it over with, Simple as that. 2 MESSIER 8 - LAGOON NEBULA
FOREWARD I began this effort with simple curiosity about what s up there. It turns out that there are lots of things up there, and it takes a good amount of effort and resources to view and photograph them. The first goal was to find the best telescope for my needs and budget. As I gained experience it became clear that in order to truly reveal those deep space objects I needed more hardware, lots of it, and a process to locate and photograph the things. That involved setting up a permanent observatory with lots of peripheral devices and software. Once the camera images appeared there were many more questions about how to improve the photography and processing steps. I wrote this book to document the knowledge I gained, the hardware and software configurations that I ended up with, along with more than 160 photographs of what s up there with descriptions. This book is intended for beginners who want to learn the basics of deep space viewing and astrophotography. The contents identify and describe the components which are necessary for a personal observatory. Methods of observation are discussed including the software tools and procedures used for imaging of deep space objects, and the processing steps used to get the best results from the raw images. All images were acquired using the hardware, software, and methods described in this book. All the images are also accompanied with descriptions. Since I had no information about any of the famous deep sky objects, I decided to look online for sites that did. There are many unknowns, and limited information on the objects short of delving into astronomy journals, however with help from several online references I did manage to get a paragraph or two on each. References are listed on the back page. Special thanks to my Lovely Partner Kathryn, for putting up with all the midnight stomping around to the skyshed, and for supporting the seemingly never ending process of developing this book. 3
CONTENTS INTRODUCTION... 5 TRACKING THE SKY... 11 TELESCOPE MOUNT... 15 TELESCOPE OPTICAL TUBE... 17 OBSERVING OBJECTIVES... 25 ASTROPHOTOGRAPHY CAMERA... 27 PRECISE STAR TRACKING - GUIDERS... 41 FOCUSING AND COLLIMATION... 45 DIGITAL PROCESSSING OF IMAGES... 47 PLANETARY IMAGE PROCESSING... 63 OBSERVATORY HARDWARE... 67 OBSERVATORY SOFTWARE... 81 MESSIER OBJECTS... 86 MOON... 199 REFERENCES... 203 4
INTRODUCTION I expect that all of us at one time or another have marveled at the things in the night sky, all those shining stars and the great expanse of the Milky Way. My first telescope showed Venus as a crescent and Saturn had rings! They were not just bright stars, they had real dimensions. To a youngster growing up under the dark farmland skies of Minnesota the night sky was wondrous. While I wondered at the sky major advances in the exploration of our universe were being realized. Astronomers explored the night sky with huge telescopes on mountain tops and made fantastic advances towards our understanding of the universe. I was impressed. Those impressive observatories are now better than ever and have been joined by many more of all types on mountain tops and in space. The universe is being revealed and we are learning how it works. Short of being an astronomer or a student in that field, most people have limited knowledge of those space objects which are large enough to be seen or photographed with a small backyard observatory. My initial observations with the 11 inch reflector mostly involved viewing the moon and planets and some of the brighter star clusters. I soon realized that no matter where I pointed the scope there were always stars visible in the eyepiece. Our galaxy holds hundreds of billions of stars. Unaided vision can only spot a tiny fraction of them. Each star moves along its path of least resistance, following the accumulated gravitational tug from all other matter in the galaxy. This has lead to a galactic merry-go-round made up of trillions of stars and planets, millions of years required for each turn of the carousel. The individual stars are not all solitary like our sun. Quite often we see stars orbiting one another in pairs or triplets or more. Sometimes very large numbers of stars are clustered together, into what are now categorized as Open Clusters and Globular Clusters. 5
NGC884, 869 DOUBLE OPEN STAR CLUSTER - Autumn RA 2h 20m DEC +57 08 6 The Double Cluster (also known as "h and chi Persei" and Caldwell 14) is the common name for the open clusters NGC 869 (right) and NGC 884, which are close together in the constellation Perseus. Both lie at a distance of 7500 light years. Mass of NGC869 and NGC884 are 3700 and 2800 solar masses respectively; the extensive halo of stars surrounding the clusters increases the number to at least 20,000 solar masses. Based on their individual stars, the clusters are relatively young at 12.8 million years old. There are more than 300 blue-white super-giant stars in each of the clusters. Their hottest main sequence stars are of spectral type B0. Dominated by bright blue stars the clusters also host a few orange stars that add to the visual interest. (6D, F2, one 3 minute exposure at ISO 1250).
The Open Clusters are generally young star groups just formed from their nebular nest, but drifting apart. Many of these open clusters are still embedded in clouds of gas and dust. On a vastly different scale, the Globular Clusters are compacted globs containing hundreds of thousands of very old stars. The stars in the globulars never drift apart because their mutual attraction does not allow escape. More than 150 of these globulars are orbiting the galactic center with orbits tilted at various angles from the galactic plane, fully detached from the galactic carousel. Fortunately none of them are headed our way. I must say that my first attempts at viewing galaxies and nebula through the eyepiece were somewhat disappointing. I had hoped to see these objects in colorful detail but most turned out to be dim grey and not well defined, or simply invisible. It seems that in my case appreciation of this type of stargazing is an acquired skill. But the experience has given me great respect for those early observers who used the first telescopes to map and categorized those objects. The discoveries were both accidental and systematic. Descriptions and mapping of objects were done the hard way; manually. Many of the larger objects were recorded in the 18th century by the early astronomers and comet hunters like Charles Messier, and with systematic exploration of the night sky by the likes of William and Caroline Herschel who made many of their own telescopes, the mirrors poured and ground personally in the house workshop. Herschel made most of his observations using his 20 foot long 18 inch reflector. His largest telescope contained a 47 inch reflecting mirror mounted inside a 40 foot tube riding on a very large Az/El mount. What they saw were clusters of stars and nebulae (space clouds). Some clouds had brighter centers, others were small faint glows surrounding a tiny star. Some clouds didn t appear to have any stars in them at all. But when seen clearly with today s technology, the nebulae are beautiful objects of form and color, and are packed with jewels for astronomers to study. 7
NGC 7293 HELIX PLANETARY NEBULA - Summer RA 22h 29.6m DEC -20 48' 8 The Helix Nebula (NGC 7293) is a planetary nebula located in the constellation Aquarius. This object is one of the closest to the Earth of all the bright planetary nebulae. The estimated distance is 700 light-years with a diameter nearly 6 light years across. The Helix Nebula has sometimes been referred to as the "Eye of God" in pop culture, as well as the "Eye of Sauron". Helix is an example of what happens to sun like stars at end of life. (SBIG, F7, three 20min exposures of each Ha Oiii Blu).
Astronomers now know that some of the objects originally classified as planetary nebulae are remnants of exploding supernovas and dying red giant stars, others are vast clouds of contracting gases and dust where clusters of stars are still being created, glowing the rarified gases like neon lights, and many are entire galaxies located far outside our own Milky Way galaxy. Astronomers have discovered billions of galaxies, island universes separated by millions of light years but gathered together into immense galactic clusters. They are so far from earth that their billions of stars could not be resolved by the telescopes of the 18th century. They appeared only as wispy swirls in space. Messier categorized 110 of the brighter objects in his catalog. Herschel recorded nearly 2500 objects in his original Catalogue of Nebulae and Clusters of Stars. An additional 109 of the most prominent objects not in the Messier catalog were added much later in the 20th century by Patrick Moore in the form of the Caldwell catalog. The new general catalog (NGC) of 7480 objects was compiled by John Lewis Dreyer in 1888. Today, there are many millions of cataloged objects; asteroids and comets, galaxies, planetary nebula, star clusters, and individual stars. The things which we see in our own Milky Way galaxy are not unique, but are common to all galaxies. It is now clear that these structures are everywhere in the universe. There are galaxies where thousands of globular clusters have been identified. Star forming regions of gas and dust have been observed which dwarf those found in our own galaxy. It s clear that the physics and chemical atomics of the universe are the same everywhere we look, and the evolution of the universe has been conveniently displayed. Because when we study these objects we are looking back in time as well as distance. Astrophotography appeals to the explorer in all of us, seeing an object materialize out the apparent darkness of space is mystical. My first long exposure was of the Apple Core Nebula (Messier 27). That discovery led to many long nights of exploring, exposing whatever I could find in the night sky. 9
NGC891 GALAXY - Autumn RA 2h 22.6m DEC +42 21' 10 NGC 891 (also known as Caldwell 23) is an edge-on unbarred spiral galaxy about 30 million light-years away in the constellation Andromeda. The galaxy is a member of the NGC 1023 group of galaxies in the Local Supercluster. The galaxy, which spans 100,000 light-years, is seen exactly edge-on revealing its thick plane of dust and interstellar gas. NGC 891 and our own Milky Way galaxy are very similar in terms of luminosity and size. Recent high-resolution images of its dusty disk show unusual filaments extending from the galactic disk into the halo of the galaxy, a result of tremendous super nova explosions and energetic stars blasting matter out of the galaxy. (6D, F10, ISO 1000, 800, 640, images 15, 20, 30 minutes)
The images under this cover represent a majority of the large and prominent objects visible from the northern hemisphere. They reveal what s up there in outer space, and what the big and bright ones look like. Included are images of all objects in the Messier Catalog and many of the Caldwell and NGC objects along with consensus or best guess summary information on each, gleaned from public internet web sites. A list of those web sites is included on the back page reference. TRACKING THE SKY As the earth rotates, the stars appear to move in arcs across the sky. In the northern hemisphere these arcs circle counter-clockwise around Polaris the North Star. However, the celestial sphere may also be envisioned as a fixed sphere surrounding the rotating earth. Positions of astronomical objects are located on the celestial sphere with Declination (DEC) and Right Ascension (RA) coordinates, similar to Latitude and Longitude on earth. Declination is the angle from the celestial equator towards the North Pole of the Celestial sphere (approximately at Polaris), just as Latitude is defined on earth. Negative Declination is likewise the angle from the Celestial equator towards the South Pole. Declination angles can be represented in decimal degrees however the common notation for Right Ascension is Hour angle, Arcminutes and Arcseconds. One Hour angle is equivalent to 15 degrees on the celestial sphere which is exactly 24 hour angles in circumference. The terms Arcminutes (1/60th degree) and Arcseconds (1/60 Arcminute) are normal units of angle but can also be related to time in the same way as the hour angle. Right Ascension ranges from 0 to 24 hours. On the celestial sphere Right Ascension is arbitrarily defined to be zero at the Vernal Equinox where the sun crosses the equator on its northward ascension in the spring. Astronomers keep track of all the subtleties associated with these definitions down to sub arcsecond levels so that star location tables always relate to true GMT regardless of earths wobble, day length inaccuracies, and other significant effects. 11
NGC2237 ROSETTE NEBULA - Winter RA 6h 33.8m DEC +04 59.9' 14 The Rosette Nebula (Caldwell 49 or NGC2237) is a star forming region weighing in at 10,000 solar masses. It lies some 5,000 light-years from Earth and is 50 light years in diameter. The open cluster of stars (NGC 2244 or C50) is being formed from the nebula's matter. The young stars at the core have ionized the gas cloud leading to emission of X-rays and the radiation we see. (SBIG, F2, RGB, 5 Red, 2 Geen, 3 Blue Images at 300SEC)