WHAT TO SEE IN A SMALL TELESCOPE July-September A Course By Stargazer University and One-Minute Astronomer www.oneminuteastronomer.com Copyright © 2011-2012 Mintaka Publishing Inc. www.oneminuteastronomer.com 2 Table of Contents Introduction............................................................................................................! 5 Tour 1 - Draco........................................................................................................! 7 Nu Draconis 7 The “head and neck” of the constellation Draco 8 39 Draconis 8 Sigma Draconis 9 UX Draconis 9 Kemble 2 9 NGC 6503 10 NGC 6543 10 Tour 2 - Hercules and Corona Borealis................................................................! 12 M13, the Great Hercules Cluster 12 NGC 6207 13 M92 14 NGC 6210 15 Dolidze-Džimšeleljšvili 9 15 Alpha Herculis 15 Kappa Herculis 16 95 Herculis 16 Zeta Corona Borealis 16 Sigma and Nu Corona Borealis 17 Tour 3 - Lyra.........................................................................................................! 18 M57 - The Ring Nebula 18 M56 - A Dim Globular 19 Delta (1,2) Lyrae 19 Stephenson 1 20 Beta Lyrae 20 Zeta Lyrae 21 Epsilon Lyrae 21 Struve 2470 and 2474 22 Tour 4 - Ophiuchus and Serpens.........................................................................! 23 Taurus Poniatowski 23 70 Ophiuchi 24 67 Ophiuchi 24 IC 4665 25 IC 4756 26 NGC 6633 26 Struve 2375 27 Collinder 350 27 NGC 6572 27 M10 28 M12 29 M5 29 What To See With A Small Telescope (July-September) v1.2 3 5 Serpentis 30 M19 30 NGC 6293 30 M9 30 Barnard 64 30 Tour 5 - Scorpius..................................................................................................! 32 Beta Scorpii 33 The constellation Scorpius, including M4, M80, M6, M7, and the “False Comet” 33 Nu Scorpii 33 Antares 34 M4 35 M80 36 The False Comet 37 M6, the “Butterfly Cluster” 38 M7 38 Tour 6 - Sagittarius (Part 1)..................................................................................! 40 The M24 Star Cloud 41 Barnard 92 and 93 41 M18 42 M17 (The Swan Nebula) 42 M16 (The Eagle Nebula) 43 M22 44 M55 45 NGC 6822 (Barnard’s Galaxy) 46 NGC 6818 46 Tour 7 - Sagittarius (Part 2)..................................................................................! 47 M8, The “Lagoon Nebula” 47 M20, The “Trifid Nebula” 48 M21 49 The Castaway Cluster 50 M28 50 Two Fine Doubles 51 Tour 8 - Scutum and Aquila..................................................................................! 52 M11, the “Wild Duck” Cluster 52 Two Double Stars Near M11 54 The region around M11 and the Scutum Star Cloud 55 Scutum Star Cloud 55 Barnard 110, 111, and 113. 55 NGC 6664 56 M26 56 NGC 6712 57 NGC 6709 57 Tour 9 - Cygnus...................................................................................................! 58 M39 59 The “North America” Nebula 59 What To See With A Small Telescope (July-September) v1.2 4 The “Northern Coalsack” 61 M29 61 NGC 6910 & IC 1318 61 61 Cygni 62 The “Blinking Planetary” 62 The Veil Nebula 63 Tour 10 - Vulpecula, Sagitta, and Delphinus........................................................! 65 The “Coathanger” 65 The Dumbbell Nebula 66 M71 67 Harvard 20 68 Gamma Delphinus 69 NGC 7006 69 The “Toadstool” 69 Appendix - Easy Math for Astronomers...............................................................! 71 Appendix - Whole-Sky Star Maps........................................................................! 73 What To See With A Small Telescope (July-September) v1.2 5 Introduction This guide helps you find and enjoy dozens of deep-sky objects with a small telescope in the mid- evening hours of July, August, and September. It contains all the maps and information you need to find interesting stars, star clusters, nebulae, and galaxies using nothing more than a 3-inch or 4- inch telescope, and to help you enjoy some of the most beautiful sights in nature. The guide assumes you are at least somewhat familiar with the set-up and operation of your telescope. If your telescope has a larger aperture than 4 inches, then you will see more detail in most objects. Sights that benefit from larger-aperture telescopes, and descriptions of what you will see with a 6-inch or 8-inch telescope are included where appropriate. The guide also assumes you are somewhat familiar with the night sky, and that you know how to locate specific major constellations. To help you get oriented, the last appendix includes three whole-sky maps that show the constellations as seen from mid-northern latitudes in July, August, and September. Your telescope may have come with at least two eyepieces, and you may have acquired one or two more. It’s important to know the magnification each of your eyepieces give you, and if possible, the field of view of each eyepiece in degrees. If you do not know how to determine these numbers, look to the first Appendix for information on how to do so. A pair of binoculars is also handy to find your way to some objects. Indeed, a few objects are best seen in binoculars. But you can get a good view in your telescope’s finder scope as well. So binoculars are not critical. One very useful accessory is a nebula filter. These optical elements thread into the back of your eyepiece and filter out skyglow and light pollution, while passing very specific colors that are common in emission and planetary nebulae. These filters go by the name of UHC (from Lumicon) or Ultrablock (from Orion), for example, and are well worth the investment. Another type of filter-- OIII (pronounced “oh-three”)-- is also useful with telescopes of 6-inch apertures or larger. Each tour in this guide includes at least one map to help you follow the directions to find the objects listed. In all maps, north is up and east is to the left. Every tour includes a table of objects described. Each type of deep-sky object is assigned a short- form code according to this legend: PN = planetary nebula OC = open star cluster What To See With A Small Telescope (July-September) v1.2 6 GC = globular star cluster DS = double/multiple star EN = emission nebula RN = reflection nebula DN = dark nebula VS = variable star GL = galaxy AS = asterism There is a lot of information in this guide, and nearly 100 deep-sky objects to explore over three months. Don’t rush it, especially if you are a near-beginner. Take your time to find, enjoy, and ponder each of these deep-sky sights. Some nights, you may see four or five sights. Some nights, especially with hard-to-find objects, you may see just one or two. Don’t worry. There is no rush. Be patient, take your time to enjoy the night sky, and to discover fascinating phenomena that most people will never see. What To See With A Small Telescope (July-September) v1.2 7 Tour 1 - Draco Draco, the Dragon, is a long, winding constellation in the far northern sky. Its distinctive shape has captured the imagination of stargazers for thousands of years. Ancient Egyptians identified the constellation as the goddess Tawaret. Arabs called these stars the “Mother Camels”. And the Greeks and Romans defined the constellation as a dragon who some say was killed by Minerva (Athena) and hurled into the sky. The constellation was surely on Ptolemy’s list of 48 original constellations of the classical world. For much of the northern hemisphere, Draco is circumpolar, which means it never sets below the horizon. The tail of the dragon begins between the bowls of the Big and Little Dippers, then heads west towards the constellation Cepheus, then back east where its distinctive head ends not far from the constellation Hercules. The constellation is not visible from the deep-southern hemisphere. Draco has dozens of faint galaxies throughout its long body, but most are too faint to see well in small telescopes. But there are some excellent double stars here, a ruby-red carbon star, and a famous planetary nebula which was the first to give up its spectroscopic secrets to 19th-century astronomers. Object Type Mag. Dist. (ly) RA Dec Comments μ Dra DS 4.9/4.9 99 17h 32.2m +55o 11’ 39 Dra DS 5.1/8.0/8.1 190 18h 23.9m +58o 48’ ο Dra DS 4.8/8.3 320 18h 51.2m +59o 23’ UX Dra - 6.0 (var) 2000 19h 21.6m +76o 34’ carbon star Kemble 2 AS ~8.0 - 18h 35.0m +72o 23’ “mini Cassiopeia” NGC 6503 GL 10.2 17 million 17h 49.5m +70o 09’ dwarf spiral NGC 6543 PN 8.1 3000 17h 58.6m +66o 38’ “Cat’s Eye” nebula Table 1 - Objects to see in the constellation Draco Nu Draconis The head of Draco is made of a distinctive asterism of the four stars beta (β), gamma (γ), xi (ξ), and mu (ν). The star xi, also called Grumium, joins the head of Draco to the rest of its body. Nu is an excellent double star with a generous spacing of 62” (arcseconds). These two white stars, both of magnitude 4.9, are easily visible in any small telescope at low magnification. What To See With A Small Telescope (July-September) v1.2 8 The “head and neck” of the constellation Draco 39 Draconis The star 39 Draconis is a little more interesting than nu. You can locate the star on a line from nu (ν) through xi (ξ) at a distance from xi that’s just a little more than the distance of xi to nu. Again, at low power in any telescope, you will see two stars here separated by 90”. The brighter primary is magnitude 5.1 and the secondary will appear two magnitudes fainter. But crank up the magnification to 125x or more, and you will see the fainter star itself resolve into two blue-white components of magnitude 8.1. The trio appear like white gems set against a fairly sparse background of space. A pleasant sight. What To See With A Small Telescope (July-September) v1.2 9 Sigma Draconis About 3.5o east of 39 Draconis, look for the unequal pair of sigma (σ) Draconis.