OF THE ROGER N. CLARK

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-- -- -- VISUAL ASTRONOMY OF THE DEEP SKY A VISUAL ATLAS OF DEEP-SKY OBJECTS • • -- 5' -- Photograph of NGC 7331. South is up . (Courtesy Palomar Observatory.) Scale: 0.6 arc-min/cm 8-inch flll.5 Cassegrain 20mm Erfle (i 17 X) 12.4mm Erfle (188X) Drawing of N GC 7331. Viewing Distance (cm) 2SX: 229 200x:29 50 X : 1 15 300 X : 19 100 X: 57 400 X : 14 Air mass: 1.08, faintest star: 14.0 at zenith, 188x; no tracking 9/ 11/83 1 1:00-1 1 :20 UT at Barbers Point, Hawaii; R. Clark 240 24 1
VISUAL ASTRONOMY OF THE DEEP SKY A VISUAL ATLAS OF DEEP-SKY OBJECTS NGC 7662, PLANETARY NEBULA IN ANDROMEDA R.A. 23h 25.9m, Dec. 42° 33' (2000.0) Technical. NGC 7662 is a small planetary nebula somewhere between 2000 and 6000 light-years away. (The distances of all planetary nebulae are poorly known.) Its diameter is between 0.3 and 0.8 light-years, depending on the distance adopted. The central star has a surface temperature around 75 000 Kelvin and has been suspected of variability, though no systematic photometric study has been completed. The nebula consists of an inner, broken ellipse surrounded by a fainter elliptical disk. The dark area in the center is perhaps similar in brightness to the outer ellipse. -- Visual. NGC 7662 has a total magnitude of 8.5 and an angular size of 32 by 28 arc. seconds, for a very high mean surface bright. ness: 15.6 magnitudes per square arc-second The planetary is visible in 7 X 50 binocula and small telescopes as a star, but will begin to show its disk at powers near 50 X. Through the 8-inch telescope under moderate skies the darker center was suspected at 334x and seen fairly well at 592 X. This object provides a good example of how the upper limit to useful magnification depends on image brightness. In the dim light levels of deep-sky astronomy, the eye has very poor resolution, so small detail may have to be magnified very highly to be detect. able. The 8-inch had no clock drive for tracking, so examination of this object was rather difficult at very high powers. Telescopes of similar size with clock drives could use higher powers still. The lesson is that if you are observing an object and feel that higher magnification may bring out more detail, go ahead and ignore the "accepted" magnification limit of 60 X per inch of objective diameter (480X on an 8-inch telescope) . See Chapter 3 for more on this subject. Photograph of NGC 7662. South is up . (Courtesy Jack B. Marling.) ---1' --- Drawing of NGC 7662. Scale: 0.25 arc-min/cm 8-inch fll l.5 Cassegrain 12.4mm Erfle (188X) 7mm Erfle (334x) l2.4mm Erfle + 3. l5x barlow (592X) Viewing Distance (cm) 50X:275 300X:46 IOOX: 138 400x:34 200x: 69 600x:23 air mass: l.41, faintest star: 13.8 at zenith, 188x; no tracking 9/5/83 14:00- 1 4:20 UT at Hawaii Kai, Hawaii; R. Clark 242 243
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OF THE ROGER N. CLARK
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Published by Sky Publishing Corpora
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CONTENTS M78 (NGC 2068) NGC 207 1,
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PREFACE During research for this bo
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VISUAL ASTRONOMY OF THE DEEP SKY AB
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VISUAL ASTRONOMY OF THE DEEP SKY TH
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.. .. .. .. VISUAL ASTRONOMY OF THE
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e viewed with enough magnification
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lens and a piano-convex eye lens. A
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controlled depends on how many laye
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The Lumicon H-Beta Filter (Figure 3
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every 1 ° in declination and 4 min
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error of only one quarter the field
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Table 4.1. Ideal limiting magnitude
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5 Making drawings and keeping recor
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more detail in the future. They add
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.. .. .. ... Contrast (C) C Log(C)
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VISUAL ASTRONOMY OF THE DEEP SKY A
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--- VISUAL ASTRONOMY OF THE DEEP SK
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--- M76 (NGC 650-651), PLANETARY NE
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-- -- M45, THE PLEIADES OPEN CLUSTE
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-- Brightest stars of the Pleiades
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M42 (NGC 1976), M43 (NGC 1982), THE
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--- --- --- VISUAL ASTRONOMY OF THE
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-- --- NGC 2023 NGC 2024, IC 434 (T
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--- --- M78 (NGC 2068), NGC 2071, D
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VISUAL ASTRONOMY OF THE DEEP SKY --
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--- M67 (NGC 2682), OPEN CLUSTER IN
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-- VISUAL ASTRONOMY OF THE DEEP SKY
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--- -- M82 (NGC 3034), PECULIAR GAL
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-- --- --- MI05 (NGe 3379) NGe 3384
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-- VISUAL ASTRONOMY OF THE DEEP SKY
Page 77 and 78: MI09 (NGe 3992), GALAXY IN URSA MAJ
Page 79 and 80: -- --- M99 (NGC 4254), GALAXY IN CO
Page 81 and 82: == -- VISUAL ASTRONOMY OF THE DEEP
Page 83 and 84: --- --- -- NGC 4449, GALAXY IN CANE
Page 85 and 86: -- -- --- VISUAL ASTRONOMY OF THE D
Page 87 and 88: --- -- M90 (NGC 4569), GALAXY IN VI
Page 89 and 90: --- -- M94 (NGC 4736), GALAXY IN CA
Page 91 and 92: -- VISUAL ASTRONOMY OF THE DEEP SKY
Page 93 and 94: -- VISUAL ASTRON0MY OF THE DEEP SKY
Page 95 and 96: -- --- -- VISUAL ASTRONOMY OF THE D
Page 97 and 98: -- -- VISUAL ASTRONOMY OF THE DEEP
Page 99 and 100: --- -- M83 (NGC 5236), GALAXY IN HY
Page 103 and 104: VISUAL ASTRONOMY OF THE DEEP SKY A
Page 107 and 108: --- VISUAL ASTRONOMY OF THE DEEP SK
Page 109 and 110: --- -- VISUAL ASTRONOMY OF THE DEEP
Page 111 and 112: ---------------- 5 / --------______
Page 115 and 116: VISUAL ASTRONOMY OF THE DEEP SKY --
Page 123 and 124: -- MI5 (NGC 7078), GLOBULAR CLUSTER
Page 127: --- VISUAL ASTRONOMY OF THE DEEP SK
Page 133 and 134: -- ·rl E I u L ro 5 +J Q) (f) 0 Y
Page 135 and 136: -- --- VISUAL ASTRONOMY OF THE DEEP
Page 137 and 138: VISUAL ASTRONOMY OF THE DEEP SKY NG
Page 139 and 140: '2 5 -rl E I U L CO '---' -t-J ill
Page 141 and 142: VISUAL ASTRONOMY OF THE DEEP SKY AP
Page 145 and 146: VISUAL ASTRONOMY OF THE DEEP SKY Ta
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Page 149 and 150: -- Appendix E A catalog of deep-sky
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Page 167 and 168: -- APPENDIX F: OPTIMUM DETECTION MA
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Page 171 and 172: --- VISUAL ASTRONOMY OF THE DEEP SK
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VISUAL ASTRONOMY OF THE DEEP SKY Ta
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VISUAL ASTRONOMY OF THE DEEP SKY Ta
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G VISUAL ASTRONOMY OF THE DEEP SKY
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INDEX INDEX M70 (NGC 6681), 312, 31
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OF THE ROGER N. CLARK

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