List of Easy Double Stars for Summer and Autumn  = easy  = not too difficult  = difficult but possible

1. Alpha Librae (Zubenelgenubi, SHJ 186). 14 hr 50.9 min -16 deg 03 min  A pair of bright stars which are extremely wide. Primary: 2.7, yellow Secondary: 5.2 (231.1″), white

2. Delta Serpentis (STF 1954). 15 hr 34.8 min +10 deg 32 min  Although it is fairly tight, it is relatively easy to split in practice with a high magnification. It is in the head (Caput) of the Serpent. Primary: 4.2, yellow Secondary: 5.2 (3.9″), yellow

3. STF 1962 in Libra. 15 hr 38.7 min -08 deg 47 min  A nicely wide pair of equally bright stars. Primary: 6.4, yellow. Secondary: 6.5 (11.7″), yellow.

4. Psi Serpentis (A 2230). 15 hr 44.0 min +02 deg 31 min  Two bright stars with a faint but very clear star between them, somewhat closer to the brighter of the two (which is ψ Ser) and all almost in a line. Primary: 6.2, yellow-white Secondary: 9.2 (193.6″), white Secondary: 7.3 (172.8″ from B)

5. Xi Scorpii (STF 1998). 16 hr 04.4 min -11 deg 22 min  A wonderful sight, two doubles as it is in same field as STF 1999. Primary: 5.2, yellow. Secondary: 7.3 (6.9″), blue.

6. STF 1999 in Scorpius. 16 hr 04.4 min -11 deg 27 min  Primary: 7.5, yellow. Secondary: 8.1 (11.6″), yellow.

7. Beta Scorpii (Graffias, H III 7). 16 hr 05.4 min -19 deg 48 min  A nicely wide pairing of a bright star and a fainter but still fairly bright star. Rather low. Primary: 2.6, white. Secondary: 4.5 (13.6″), blue.

8. Omega Scorpii (no designation). 16 hr 06.8 min -20 deg 40 min  A super-wide pair of bright stars, but rather low. Primary: 3.9, white. Secondary 4.3 (877.3″), white.

9. Kappa Herculis (Marfik, STF 2010) 16 hr 08.1 min +17 hr 03 min  A nice wide easy coloured double. Mistakenly called Maasym in the Celestron handset. Primary: 5.1, yellow. Secondary: 6.2 (27.0″), blue.

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10. Nu Scorpi (Jabbah, H V 6 and BU 120). 16 hr 12.0 min -19 deg 28 min  &  A more challenging version of the famous double-double in Lyra. The wide pair is easy, but splitting these two stars is difficult and will require at least 5″ aperture. The secondaries take the colours of their primaries. Primary (1): 4.4, white. Secondary (1): 5.3 (1.2″). Primary (2): 6.6 (41.2″ from Primary 1), white or red. Secondary (2): 7.2 (2.2″).

11. 17/16 Draconis (STFA 30/STF 2078). 16 hr 36.2 min +52 deg 55 min  &  The two main stars 17 and 16 Draconis are an easy bright pair. 17 Draconis can be split, but will require a higher magnification as it is fairly tight. 17 Dra: 5.4, white or yellow-white. 16 Dra (C): 5.5 (90.1″), white. 17 Dra B: 6.4 (3.1″), white or yellow-white.

12. 36-37 Herculis (STFA 31). 16 hr 40.6 min +04 deg 13 min  Primary: 5.8, white. Secondary: 6.9 (69.3″), blue or yellow.

13. Mu Draconis (Arrakis, STF 2130). 17 hr 05.3 min +54 deg 28 min  This tight equal double requires a high magnification (at least 150x). It is the planet that is called Arrakis in Frank Herbert’s Dune series, which circled the bright southern star Canopus. Primary: 5.7, yellow. Secondary: 5.7 (2.5″), yellow.

14. Alpha Herculis (Rasalgethi, STF 2140). 17 hr 14.6 min +14 deg 23 min  A colourful pair, the main star is actually variable. Primary: 3.5 (act. 3.1-3.9), yellow. Secondary: 5.4 (4.6″), blue or green (or red).

15. 36 Ophichui (SHJ 243). 17 hr 15.3 min -26 deg 36 min  Rather low in British skies. Primary: 5.1, yellow. Secondary: 5.1 (4.9″), yellow.

16. Omicron (39) Ophichui (H III 25). 17 hr 18.0 min -24 deg 17 min  Again rather low for Havering, but nice if it can be seen clearly. Described by Revd Thomas Webb as beautiful. Primary: 5.2, yellow or orange. Secondary: 6.6 (10.3″), blue or blue-white.

17. Rho Herculis (STF 2161). 17 hr 23.7 min +37 deg 09 min  Primary: 4.5, yellow or bluish white. Secondary: 5.4 (3.9″), white or greenish-white.

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18. Nu Draconis (Kuma, STFA 35). 17 hr 32.2 min +55 deg 11 min  Bright extremely wide equal double, sometimes described as car headlights in a barren sky. Primary: 4.9, yellow-white or white. Secondary: 4.9 (63.4″), yellow-white or white.

19. Psi Draconis (Dziban, STF 2241). 17 hr 41.9 min +72 deg 09 min  Primary: 4.6, yellow. Secondary: 5.6 (30.0″), yellow.

20. 61 Ophichui (STF 2202). 17 hr 44.6 min +02 deg 35 min  Primary: 6.1, white (or yellow). Secondary: 6.5 (20.5″), white (or yellow).

21. Mu Herculis (STF 2220). 17 hr 46.5 +27 deg 43 min  It is difficult to the faint red star through the glare of the main star, but I have included it as the secondary is actually a pair of red dwarfs, but difficult to split as the gap is only 1.1″. Primary: 3.5, yellow. Secondary: 9.8, red (or purple).

22. 40/41 Draconis (STF 2308). 18 hr 00.2 min +80 deg 00 min  One of the northernmost doubles. Primary: 5.7, yellow. Secondary: 6.0 (18.7″), yellow.

23. 95 Herculis (STF 2264). 18 hr 01.5 min +21 deg 36 min  Primary: 4.9, yellow or white. Secondary: 5.2 (6.3″), yellow.

24. 70 Ophichui (STF 2272). 18 hr 05.5 min +02 deg 30 min  A very colourful pair. Primary: 4.2, yellow or orange. Secondary: 6.2 (6.2″), orange or red.

25. 100 Herculis (STF 2280). 18 hr 07.8 min +26 deg 06 min  Wide, bright and equal. Primary: 5.2, white. Secondary: 5.2 (14.2″), white.

26. Epsilon Lyrae (STF 2382 & STF 2383). 18 hr 44.3 min 39 deg 40 min  &  The famous “Double-Double”. An extremely wide pair (STFA 37), visible in the finderscope, but the two main stars can only be split with difficulty, use a high magnification. The position angles are at right angles to each other. All the stars are white with a yellowish-green tint. Primary (1): 4.7, white. Primary (2): 4.6 (207.9″), white.

Primary (1): 5.2 (dimmer because the light from B is not included). Secondary (1): 6.1 (2.3″). Primary (2): 5.3. Secondary (2): 5.4 (2.4″).

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27. Zeta Lyrae (STFA 38). 18 hr 44.8 min +37 deg 36 min  Primary: 4.3, yellow. Secondary: 5.6 (41.1″).

28. 5 Aquilae (STF 2379). 18 hr 46.5 min -00 deg 58 min  Primary: 5.9, yellow-white or white. Secondary: 7.0 (12.6″), blue.

29. STF 2391 in Scutum. 18 hr 48.7 -06 deg 00 min  Mentioned only because it is the same field as H 6 50, but still worth seeing. It is also near the Wild Duck Cluster (M11). Primary: 6.5, yellow. Secondary: 9.6 (38.0″), purple or turquoise.

30. H 6 50 in Scutum. 18 hr 49.7 min -05 deg 55 min  Primary: 6.2, orange. Secondary: 8.2 (110.6″), white.

31. STT 525 in Lyra. 18 hr 54.9 min +33 deg 58 min  &  The AB pair is very unequal and tight, thus very difficult. The AB-C pair is easy. Primary: 6.1, yellow. Secondary (B): 9.1 (1.8″). Secondary (C): 7.6 (45.2″), blue.

32. 15 Aquilae (SHJ 286). 19 hr 05.0 min -04 deg 02 min  Primary: 5.5, yellow. Secondary: 7.0, blue.

33. STF 2470 and STF 2474 in Lyra. The unknown double-double in Lyra. A brilliant double-double pair, wider than ε Lyrae and more colourful, but dimmer. The position angles are exactly the same and separations are exactly the same, and the brightness almost exactly the same, weird!

34. STF 2470: 19hr 08.8 min +34 deg 46 min  Primary: 7.0, white. Secondary: 8.4 (13.8″), blue.

35. STF 2474: 19 hr 09.1 min +34 deg 36 min  Primary: 6.8, yellow. Secondary: 7.9 (15.9″), blue.

36. Theta Serpentis (Alya, STF 2417). 18 hr 56.2 min +04 deg 12 min  A wonderful sight, almost the equal of Albireo. Two white stars wide apart with tantalising tints, which I see as greenish and bluish. One of my favourites. In the tail (Cauda) of the Serpent. Primary: 4.6, white. Secondary: 4.9, white (22.3″).

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37. STF 2486 in Cygnus. 19 hr 12.1 min +49 deg 51 min  Primary: 6.5, yellow. Secondary: 6.7 (7.2″), yellow.

38. Alpha Vulpeculae (Anser, STFA 42). 19 hr 28.7 min +24 deg 40 min  The name of Alpha Vulpeculae is a relic of the original name of the constellation created by Johannes Hevelius, Vulpecula et Anser (the Little Fox and Goose, the goose being in the fox’s mouth). This extremely wide pair is an easy finderscope object. Primary: 4.6, dark yellow or white. Secondary (8 Vul): 5.9 (426.6″), white or pale yellow.

39. Beta Cygni (Albireo, STFA 43). 19 hr 30.7 min +27 deg 58 min  The most wonderful of binaries, two bright stars with the perfect separation and easily resolved, with warm easily recognised colours. Easily spotted as the “head” of the Swan. Probably an optical double, although this has been debated. Primary: 3.2, orange-yellow. Secondary: 4.7 (34.7″), deep blue.

40. S722 in Sagittarius. 19 hr 39.2 min -16 deg 54 min  A nice if dim double in the very low constellation of Sagittarius. Close to 54 Sagittarii if not quite in the same field. Primary: 7.2, bluish-white. Secondary: 7.5 (9.9″), bluish-white.

41. 54 Sagittarii (HJ 599). 19 hr 40.7 min -16 deg 18 min  This would be a splendid double if it were higher in the sky, but still worth observing. Primary: 5.4, yellow. Secondary: 7.7 (45.3″), blue or white.

42. H N 84 in Sagitta. 19 hr 39.4 min +16 deg 34 min  The faint secondary is surprisingly clear. A little bit like Albireo but dimmer. Primary: 6.4, yellow. Secondary: 9.5 (28.3″), blue.

43. 16 Cygni (STFA 46). 19 hr 41.8 min +50 deg 32 min  Primary: 6.0, white. Secondary: 6.2 (39.7″), white.

44. 57 Aquilae (STF 2594). 19 hr 54.6 min -08 deg 14 min  The best double in the Eagle, which lies under the bright star Altair. 56 Aql is in the same field and is also a double, but the secondary is very faint (5.8-12.3, 46.4″). Primary: 5.7, yellow-white. Secondary: 6.4 (35.7″), bluish white.

45. Theta Sagittae (STF 2637). 20 hr 09.9 min +20 deg 55 min  This nice triple is in a rich field of stars but stands out. The two bright stars are very wide and a faint but clear star is closer to the primary. Primary: 6.6, white. Secondary (B): 8.9 (11.5″), red or grey. Secondary (C): 7.5 (90″), white.

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46. 30/31 Cygni (Omicron-1 Cygni, STFA 50). 20 hr 13.6 min +46 deg 44 min  There is a third faint companion to this bright wide double which is easily seen in the finderscope. The three stars form a flattened V. Primary: 3.9, white. Secondary (C): 7.0 (111.0″), white. Secondary (D): 4.8 (333.8″), white.

47. Alpha Capricorni (Algiedi, STFA 51). 20 hr 18.1 min -12 deg 33 min  A bright and extremely wide double which can be seen in the finderscope. Beta Capricorni can also be seen in the finderscope field. There are faint stars very wide of both main stars, but I will not bother with them here. Primary: 3.7, yellow-white. Secondary: 4.3 (381.2″), yellow-white.

48. Beta Capricorni (Dabih, STFA 52). 20 hr 21.0 deg -14 deg 47 min  A lovely triple which can be seen near Alpha Capricorni in the finderscope. The three stars form a very obtuse triangle with the bright yellow star at the peak, a fairly bright blue star at one corner and a much fainter ashy star at the third corner. Primary: 3.2, yellow. Secondary (B): 6.1 (205.4″), blue (or bluish-white). Secondary (C): 8.8 (226.1″), ashy.

49. STF 2687 in Cygnus. 20 hr 26.4 min +56 deg 38 min  This pair looks brighter to me than listed – what do you think? Primary: 6.4, white or yellow-white. Secondary: 8.3 (26.9″), blue or blue-green.

50. Rho (11) Capricorni (SHJ 323). 20 hr 28.9 min -17 deg 49 min  Another extremely wide double in the Sea-Goat. The main star can be split but it is very tight (5.0-6.9, 1.6″). Primary: 5.0, yellow. Secondary: 6.7 (258.7″), blue or red.

51. Omicron (12) Capricorni (SHJ 324). 20 hr 29.9 deg -18 deg 35 min  Primary: 5.9, yellow. Secondary: 6.7 (21.8″), yellow or blue.

52. STF 2725 in Delphinus. 20 hr 46.2 min +15 deg 54 min  A nice if dim double immediately south of Gamma Delphini and in the same field. However the glare of Gamma Delphini makes it difficult to see hence  rather than . Primary: 7.5, yellow. Secondary: 8.2 (5.9″), blue.

53. Gamma Delphini (STF 2727). 20 hr 46.7 min +16 deg 07 min  This colourful bright double is the nose of the Dolphin. Primary: 4.4, yellow. Secondary: 5.0 (9.0″), bluish-green.

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54. Epsilon (1) Equulei (STF 2737). 20 hr 59.1 min +04 deg 18 min  Primary: 5.3, yellow. Secondary: 7.1 (10.5″), blue or red (or reddish yellow).

55. 61 Cygni (STF 2758). 21 hr 06.9 min +38 deg 45 min  This is a historically important star as it was the first star to have its distance measured by its parallax, by Friedrich Bessel in 1838. Although Thomas Henderson had measured the distance of Alpha Centauri earlier, his publication was delayed by his ill-health and return to Scotland from South Africa. It is also nearby, only 11.4 light-years away. The colours are particularly vibrant being a vivid tangerine orange. Primary: 5.2, orange. Secondary: 6.1 (31.6″), orange.

56. Gamma (5) Equulei (STFA 54). 21 hr 10.3 min +10 deg 08 min  A good finderscope object. The main star is sometimes described as yellow, but this may be in contrast to a faint very tight companion I have ignored here (KNT 5: 8.7, 1″). I would actually call it bluish-white, possibly a result of the blue light of the faint companion. Primary: 4.7, white. Secondary (D): 6.1 (335.8″), white.

57. Beta Cephei (STF 2806). 21 hr 28.7 min +70 deg 34 min  Despite its faintness, the secondary is obvious. Primary: 3.2, white. Secondary: 8.6, blue or green.

58. STF 2186 in Cepheus. 21 hr 39.0 min +57 deg 29 min  This triple lies in the rich star field of the cluster IC 1396 with some nebulosity. The main star is in the middle and is flanked by two fainter equally bright stars. The unremarkable and dim double STF 2819 is in the same field of view (7.4-8.6, 12.8″, white or yellow and blue). The famous red star Mu Cephei (Herschel’s garnet star) is nearby. Primary: 5.7, yellow-white or white. Secondary (C): 7.5, blue or violet. Secondary (D): 7.5, yellow or green (or white).

59. Epsilon Pegasi (Enif, S798). 21 hr 44.2 min +09 deg 53 min  This is the famous ‘Pendulum star’. John Herschel pointed out that if you tap the telescope, the central star soon settles down but the faint companion continues to swing back and forth (the ‘Mexican bean trick’ with Tau Canis Majoris is similar). This is owing to the greater persistence of vision with the brighter star. Primary: 2.5, yellow. Secondary: 8.7 (147.0″), purple or blue.

60. Xi Cephei (Kurah, STF 2863). 22 hr 03.8 min +64 deg 38 min  Primary: 4.5, yellow (or white). Secondary: 6.4 (8.0″), blue(-violet) or yellow.

61. 41 Aquarii (H N 56). 22 hr 14.3 min -21 deg 04 min  Primary: 5.6, yellow. Secondary: 6.7 (5.2″), blue (or violet).

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62. Delta Cephei (Alfirk, STFA 58). 22 hr 29.2 min +58deg 25 min  The famous variable which gives its name to the Cepheid ‘standard candles’. It is also an easy and colourful double. The main star varies from 3.5 to 4.4 over 5.366 days. Primary: 4.2, yellow. Secondary: 6.1 (40.6″), blue.

63. 8 Lacertae (STF 2922). 22 hr 35.9 min +39 deg 38 min  See if you can spot the nebulosity which is supposed to exist around this double. Primary: 5.7, white. Secondary: 6.3 (22.3″), white.

64. 94 Aquarii (STF 2998). 23 hr 19.1 min -13 deg 28 min  The secondary is a particularly lovely shade of blue. The best double in the Water-carrier. Primary: 5.3, yellow. Secondary: 7.0 (12.2″), blue (or purple).

65. 107 Aquarii (H 2 24). 23 hr 46.0 min -18 deg 41 min  Primary: 5.7, yellow (or white). Secondary: 6.5 (6.6″), blue or dark yellow.

Peter J. T. Morris, 19 March 2014 With thanks to the Washington Double Star Catalogue and the Simbad database.

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