Archive for the ‘NB75’ Category

Orion star hop!

Posted: February 11, 2012 in Constellations, Deepsky, NB75, Observing
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The bright star pattern of Orion is a great place to begin navigating the sky at this time of the year.  Orion is easy enough to find; face south and look for three bright stars a straight line.  Those stars mark Orion’s Belt and is the centre of the constellation.

If you can find the stars of Orion then you can use the shape to find other interesting stuff in the sky.  For example, you can hop from the three Belt stars to a few other things.

Follow the line from the stars down towards the horizon and you spot the brilliantly twinkling star called Sirius.  This is actually the brightest star in the sky (and one the nearest to us).  Sirius is a bit more massive than the Sun and this translates to it putting out more that 25 times as much energy as the Sun does. It is only outshone in the night sky by the planets Venus, Jupiter and occasionally Mars.  From the UK it never gets particularly high in the sky and so its light has to pass through the atmosphere at a shallow angle.  This causes it to twinkle violently and flash different colours of the rainbow.  This can make for some interesting pictures!

Following the Belt stars upwards will bring you to a bright orange star called Aldebaran which seems to be part of a V-formation of fainter stars around it.   Aldebaran is an old orang giant star about 65 light years away.  It’s the kind of bloated star that our Sun will evolve into when the nuclear fuel runs out in five or six billion years time.  Although Aldebaran seems to be embedded in the faint scattering of stars around it – this is an illusion.  The Hyades star cluster is more than twice as distant as Aldebaran.  This means we are closer to Aldebaran than it is to the stars that seem to be next to it in the sky!  Binoculars give a great view of Aldebaran and the Hyades cluster.

Continue that line from Orion up a bit further up in the same direction and you’ll arrive at the Pleaides star cluster (also called The Seven Sisters on account of how keen sighted people claim to be able to see seven stars….I can count five).  Astronomers give it the somewhat less romantic name M45.  The Pleaides are even more remote than the Hyades – about three times further away.  Here’s a picture Malcolm Robinson took of the cluster a couple of years ago:

The purpose of learning to hop from star to star is to help build up your familiarity with the night sky.  And it’s also useful for tracking down really faint fuzzy objects like nebulas and star clusters.  Here’s a nice example for those of you with binoculars or telescopes using what you’re seen so far.  There’s an nice little cluster of stars, called M41, in the constellation Canis Major (the Great Dog).  It’s near the star Sirius so we’ll use that to hop to M41.

So find Sirius, with binoculars or telescope and move down and slightly to the right.  M41 should jump out in your field of view with binoculars.  Look for those fainter stars to the south of Sirius to help you if you need it.

Here’s a simulated view of the cluster at low magnification (about 40x):

M41 is on the fringe of naked eye visibility.  Although it is best seen with a telescope there are suggestions it was seen by Aristotle in the 4th century BC.  It’s a scattering of about a hundred stars covering an area bigger than the full moon.  Many telescopic observers report seeing long chains of stars radiating away from the centre of cluster where a brighter orange giant star is found.  M41 is a typical example of the star clusters found throughout the Milky Way arching across the winter sky from northern to southern horizon.

More soon…

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NASTRO Binocular 75

Posted: November 13, 2011 in Deepsky, NASTRO, NB75, Observing

This post is a follow up to the presentation I gave at the NASTRO meeting last Thursday.

The NASTRO Binocular 75 (NB75) is an observing list that I compiled nearly 10 years ago.  There are lots of lists or catalogues that are familiar to amateur astronomers.  The Messier and Caldwell catalogues are famous examples.  My reasons for drawing up a new list were:

  • I wanted an observing list I could complete; several Messier objects aren’t visible from Northumberland. No closure!
  • As Training Officer at NASTRO, I wanted a list of bright objects potentially visible with binoculars that members could use to hone their observing skills (like reading star charts, or using astronomy software as well as star hopping)
  • Knowing about more objects to track down will add variety.  I’ve seen so many people revisiting the same dozen or so objects in the night sky because they can’t find (or don’t know about) anything else that they can see.
  • It was fun to do.
There are very few current members of NASTRO who saw the list in its first form so I feel I can put it out again.  Also, with social networking more familiar to people these days, then hopefully some degree of collaboration between local astronomers will be possible.
I’ve no doubt that anyone undertaking the list will become totally familiar with the night sky by the time they’ve tracked down the 75th object.
So, without further ado, here is the list of all 75 objects.

ID

Name Class Con RA Dec

Mag

Size

Best Difficulty

1

M 31 Gal And 00h43m25.9s +41°20’19”

4.3

2.6°x 1.1°

obvious

2

ET Cluster Open Cas 01h20m23.8s +58°21’12”

5.1

20.0′

obvious

3

M 103 Open Cas 01h34m14.6s +60°42’53”

6.9

5.0′

obvious

4

M 33 Gal Tri 01h34m33.6s +30°43’28”

6.4

61.7’x 36.3′

easy

5

Collinder 463 Open Cas 01h46m48.8s +71°52’23”

5.8

57.0′

easy

6

NGC 663 Open Cas 01h47m02.4s +61°17’53”

6.4

14.0′

obvious

7

NGC 752 Open And 01h58m26.3s +37°50’46”

6.6

75.0′

detectable

8

Muscle Man Cluster Open Cas 02h15m38.5s +59°32’35”

4.4

60.0′

obvious

9

Perseus Double Cluster Open Per 02h19m54.3s +57°11’08”

4.3

18.0′

obvious

10

M 34 Open Per 02h42m54.1s +42°48’52”

5.8

35.0′

easy

11

Collinder 33 Open Cas 03h00m20.0s +60°26’52”

5.9

39.0′

easy

12

Collinder 39 Open Per 03h25m13.6s +49°54’16”

2.3

5.0°

easy

13

M 45 Open Tau 03h47m45.0s +24°09’16”

1.5

120.0′

obvious

14

Kemble’s Cascade (& NGC 1502) Open Cam 04h08m57.8s +62°21’45”

4.1

8.0′

obvious

15

NGC 1528 Open Per 04h16m20.7s +51°14’39”

6.4

16.0′

obvious

16

NGC 1545 Open Per 04h21m54.3s +50°16’51”

4.6

18.0′

obvious

17

Hyades Open Tau 04h27m37.0s +15°53’38”

0.8

5.5°

obvious

18

NGC 1647 Open Tau 04h46m39.1s +19°08’12”

6.2

40.0′

easy

19

NGC 1746 Open Tau 05h04m35.7s +23°47’10”

6.1

42.0′

easy

20

M 38 Open Aur 05h29m30.5s +35°51’23”

6.8

20.0′

easy

21

NGC 1981 Open Ori 05h35m46.3s -04°25’24”

4.2

28.0′

obvious

22

Collinder 69 Open Ori 05h35m47.4s +09°56’27”

2.8

70.0′

obvious

23

M 42 Neb Ori 05h35m55.0s -05°22’30”

4

40.0’x 20.0′

obvious

24

NGC 1977 Neb Ori 05h35m55.2s -04°50’30”

7

20.0′

difficult

25

Orion’s Belt Open Ori 05h36m08.2s -01°05’31”

0.6

2.3°

obvious

26

M 36 Open Aur 05h37m07.7s +34°08’45”

6.5

10.0′

obvious

27

M 37 Open Aur 05h53m07.0s +32°33’16”

6.2

14.0′

obvious

28

37 Cluster Open Ori 06h09m06.5s +13°57’44”

7

5.0′

obvious

29

M 35 Open Gem 06h09m45.8s +24°20’47”

5.6

25.0′

obvious

30

NGC 2175 Open Ori 06h10m23.5s +20°29’00”

6.8

22.0′

easy

31

NGC 2232 Open Mon 06h27m52.0s -04°45’55”

4.2

53.0′

obvious

32

NGC 2244 Open Mon 06h32m34.7s +04°55’58”

5.2

29.0′

obvious

33

NGC 2264 Open Mon 06h41m39.1s +09°52’59”

4.1

39.0′

obvious

34

M 41 Open CMa 06h46m33.3s -20°46’05”

5

39.0′

easy

35

NGC 2281 Open Aur 06h49m09.3s +41°03’42”

7.2

25.0′

easy

36

NGC 2301 Open Mon 06h52m23.3s +00°26’44”

6.3

14.0′

obvious

37

M 50 Open Mon 07h03m17.9s -08°24’01”

7.2

14.0′

easy

38

M 47 Open Pup 07h37m09.2s -14°30’32”

4.3

25.0′

obvious

39

M 46 Open Pup 07h42m20.1s -14°50’13”

6.6

20.0′

easy

40

M 48 Open Hya 08h14m19.4s -05°47’09”

5.5

30.0′

easy

41

M 44 Open Cnc 08h41m06.1s +19°37’19”

3.9

70.0′

obvious

42

M 67 Open Cnc 08h51m58.1s +11°45’14”

7.4

25.0′

detectable

43

M 81 Gal UMa 09h56m31.5s +69°00’09”

7.8

21.9’x 10.5′

easy

44

Collinder 256 Open Com 12h25m41.4s +26°01’57”

2.9

120.0′

obvious

45

Mizar DVar UMa 13h24m22.6s +54°51’39”

2.1

obvious

46

M 3 Glob CVn 13h42m43.2s +28°19’04”

6.3

18.0′

easy

47

M 5 Glob Ser 15h19m09.6s +02°02’30”

5.7

23.0′

easy

48

M 13 Glob Her 16h42m05.5s +36°26’25”

5.8

20.0′

obvious

49

M 12 Glob Oph 16h47m50.7s -01°57’56”

6.1

16.0′

easy

50

M 10 Glob Oph 16h57m46.3s -04°06’59”

6.6

20.0′

easy

51

M 92 Glob Her 17h17m27.8s +43°07’40”

6.5

14.0′

obvious

52

IC 4665 Open Oph 17h46m52.7s +05°42’55”

5.3

70.0′

easy

53

M 23 Open Sgr 17h57m45.9s -18°59’05”

5.9

29.0′

easy

54

Collinder 359 Open Oph 18h01m41.5s +02°54’10”

3

4.0°

easy

55

M 20 Neb Sgr 18h03m05.2s -22°59’07”

6.3

16.0’x 9.0′

challenging

56

M 8 Neb Sgr 18h04m45.6s -24°23’07”

5

17.0’x 15.0′

easy

57

M 24 Open Sgr 18h19m07.8s -18°24’01”

11.1

6.0′

challenging

58

M 16 Neb Ser 18h19m28.8s -13°48’45”

6

9.0’x 4.0′

difficult

59

M 17 Neb Sgr 18h21m29.1s -16°10’34”

6

11.0′

difficult

60

NGC 6633 Open Oph 18h27m49.6s +06°31’08”

5.6

20.0′

obvious

61

M 25 Open Sgr 18h32m29.0s -19°06’23”

6.2

29.0′

easy

62

M 22 Glob Sgr 18h37m07.5s -23°53’32”

5.2

32.0′

easy

63

Epsilon Lyrae (Double Double) Doub Lyr 18h44m43.4s +39°41’16”

4.7

obvious

64

M 11 Open Sct 18h51m43.3s -06°15’12”

6.1

32.0′

easy

65

Collinder 399 Open Vul 19h25m55.1s +20°12’42”

4.8

89.0′

easy

66

M 27 PNe Vul 20h00m07.3s +22°45’32”

7.3

8.0′

obvious

67

NGC 6871 Open Cyg 20h06m25.9s +35°49’01”

5.8

29.0′

obvious

68

NGC 7039 Open Cyg 21h11m14.2s +45°40’20”

6.8

14.0′

obvious

69

M 15 Glob Peg 21h30m33.3s +12°13’24”

6.3

18.0′

easy

70

M 39 Open Cyg 21h32m14.6s +48°29’35”

5.3

29.0′

obvious

71

M 2 Glob Aqr 21h34m04.6s -00°46’02”

6.6

16.0′

easy

72

Garnet Star DVar Cep 21h43m53.2s +58°50’31”

4.3

obvious

73

NGC 7243 Open Lac 22h15m37.5s +49°57’52”

6.7

29.0′

easy

74

M 52 Open Cas 23h25m22.5s +61°39’55”

8.2

15.0′

easy

75

NGC 7686 Open And 23h30m43.2s +49°12’18”

5.6

14.0′

obvious

I compiled the list using SkyTools 3.  It’s ordered by Right Ascension, which approximately means that the objects at the top of the list were well placed in the sky at midnight at the start of Autumn.  So now, near the middle of November, it should be possible to track down the first 15 or 20 objects before late evening.

The list contains a number of different types of object:

Here is the 65th entry in the NB75 list – The Coathanger.

Collinder 399 in the constellation Vulpecula. Popularly known as the Coathanger. Image by Malcolm Robinson.

The response from NASTRO members seemed enthusiastic.  The list is a starting point; each object has an interesting back story and will add a little (or a lot) to your picture of the universe.
I’ll discuss this more and add some more resources to support this soon.  Emma will be adding things to the main NASTRO website as well.