100 years ago, galaxies were thought to be gas clouds within our own galaxy. As ways to measure their distance were developed, they began to be understood during the first half of the 20th century. The latter half of the 20th century saw the first amazing black and white photographs published of these distant objects. Today, we are able to capture detailed color images of these “islands in the sky” from our own backyards. What an amazing past 100 years it has been for our ability to understand and image the most awesome objects in the universe!

This poster captures the brightest 80 galaxies visible from the northern hemisphere. Most of these objects are north of -30 degrees declination, with NGC 5128 being the furthest south object at -43 degrees. The list does not include 8 galaxies which are south of -50 degrees.

What does it mean to be “the brightest”? For this poster, I am using the blue apparent magnitude listed in the Third Reference Catalog of Bright Galaxies. This magnitude is a measure of the galaxy brightness over its extended area, obtained by summing the luminosity over the galaxy area. The resulting magnitude value is the same as that of a star (e.g., a galaxy with a magnitude of 10 emits the same total amount of light as a star of magnitude 10).

However, if a galaxy is large, this magnitude is spread out over a large area, making the resulting brightness per unit area (i.e., surface brightness) small and therefore hard to see. A good example of this are the 2 dwarf galaxies included here, which are "bright" but are large and hard to see. I originally felt that surface brightness would be a better measure of a “bright galaxy”. But that list was dominated by small bright elliptical galaxies, ignoring many of the largest and most beautiful galaxies such as M33 and M101, so I went with magnitude instead.

The poster lists the top 80 galaxies in order of brightness, standing with the brightest (Andromeda) at top left. The magnitudes range from 4.4 to 10.5. Object data is displayed along with the image of each object. The data is in this order: Size (in arc-minutes), Magnitude / Surface Brightness, and Declination.

A number of things surprised me about this list:

- 21 of these 80 bright galaxies are Arp objects. I typically think of Arp objects as being small and faint.

- Only 12 galaxies on this list are elliptical galaxies, typically considered to be the brightest of galaxies. Using magnitude as a brightness proxy increased the number of larger spiral galaxies on this list.

- The 2 dwarf galaxies seem unrealistically faint. My image of this close galaxies (both less than 0.5 million light years away) does not seem to capture their brightness in a way which is consistent with their calculated magnitude.

I have included this poster, along with individual images of each object shown here, in my Astrobin Bright Galaxy Collection. Please reply if you identify any errors.

The poster objects are as follows:

1. M 31

2. M 33

3. NGC 5128

4. M 81

5. NGC 253

6. M 83

7. M 101

8. NGC 55

9. NGC 300

10. M 110

11. NGC 2403

12. M 51

13. M 104

14. M 94

15. M 32

16. Fornax Dwarf

17. M 106

18. IC 342

19. M 82

20. NGC 6822

21. M 63

22. M 64

23. M 49

24. NGC 1291

25. NGC 1316

26. M 87

27. M 77

28. NGC 6946

29. NGC 7793

30. M 66

31. NGC 247

32. NGC 2903

33. NGC 4631

34. M 60

35. NGC 3521

36. M 86

37. NGC 3115

38. IC 1613

39. M 74

40. NGC 4449

41. M 85

42. M 100

43. NGC 4236

44. NGC 2997

45. M 84

46. NGC 2841

47. NGC 185

48. M 96

49. NGC 4725

50. NGC 4697

51. M 61

52. NGC 4490

53. NGC1097

54. M 105

55. NGC 4214

56. M 65

57. M 90

58. NGC 3621

59. NGC 3628

60. NGC 1365

61. NGC 5102

62. NGC 7331

63. NGC 1023

64. M 88

65. NGC 3184

66. NGC 3109

67. NGC 4699

68. NGC 4565

69. NGC 4636

70. M 99

71. NGC 3344

72. NGC 5195

73. NGC 4559

74. NGC 147

75. M 58

76. PGC 3589

77. NGC 5247

78. NGC 4665

79. NGC 1232

80. M 95