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Southern Cross - March 2001

• Columba by Jenni Kay FRAS

Columba

Jenni Kay FRAS

Naked eye view

This constellation is easy enough to find being made up of bright, naked eye stars. However, while it does not show any easily recognisable shape in the sky, a good field-guide star chart will help locate it. Overall, the constellation appears as a long and lanky collection of stars, mostly in long chains lying east to west. The last few stars of Columba in the west lay near the "back legs" of the dog shape of Canis Major.

The following observations were made with a 12.5" f/5 Newtonian, from my semi-rural home site in Lobethal, SA. Typically, the skies here have a limiting naked eye magnitude of 6.1, with the seeing rated at ANT II-III. Unless otherwise stated, the following objects are galaxies.

NGC 1792 : 05 05.2 -37 59 (9.9v; 5.5' x 2.5'; surface brightness 12.6v; position angle 136degrees.)

83X: A showpiece! Very obvious, bright, large, oval - elongated in shape, smooth hazy glow.

150X: Much improved - bright, 3.5' x 1.5' in size, major axis is SE - NW, high surface brightness, with a smooth and even glow from edge to edge. There are at least four 13 mag stars superimposed; one to the SW edge, another near the NW edge, and two near the centre. Overall, the whole view is quite magnificent with this bright galaxy set in a bright star field. NGC 1808 lies nearby to the NE.

NGC 1800 : 05 06.4 -31 57 (12.6v; 2.1' x 1.0'; sb 13.3v; pa112d.)

83X: Obvious enough with some care and averted vision - relatively bright, small, oval- elongated, very smooth hazy glow. There is a 13 mag field star detached off the E edge.

150X: Much improved view - relatively bright, elongated, 50" x 25", major axis lies SE - NW, high surface brightness, with a brightening towards the centre. In moments of steady seeing I suspect there may be a couple of very faint stars superimposed over the galaxy glow.

NGC 1808 : 05 07.7 -37 31 (9.9v; 5.2' x 2.3'; sb 12.4v; pa 138d.) 41.0' NE of NGC 1792.

83X: Stunning! Bright, long, elongated glow, with a brighter, very small, round, central core.

150X: Improved view - bright, long and broad, 6.0' x 1.5'; with a brighter core 15" in size. The major axis is SE - NW, the galaxy has a high surface brightness, and the galaxy glow gradually fades out towards the edges. Adding to the overall visual effect of the view, south of the galaxy there is a chain of five bright 10 mag field stars in a line almost E-W. NGC 1827 lies nearby to the NE.

NGC 1811 : 05 08.7 -29 16 (13.5v; 1.7' x 0.4'; sb 12.9v; pa60d.)

83X: First of two in a close pair with N1812. Needs some care and averted to detect being very faint, small, a little elongated in shape, smooth dim glow.

150X: Much improved - faint, 30" x 20", major axis lies SW - NE, very smooth low surface brightness. N1812 lies to the NE.

NGC 1812 : 05 08.9 -29 16 (12.7v; 1.3' x 0.8'; sb 12.6v; pa 6d.) 2.5' NE of NGC 1811.

83X: Relatively faint, small, round - little elongated, very smooth glow.

150X: Improved view - relatively bright, 50" x 20", major axis lies nearly N-S, with a smooth high surface brightness. The soft galaxy glows are a little lost among the bright and faint field stars, and require a few moments to pick them out.

NGC 1827 : 05 10.1 -36 58 (12.5v; 3.3' x 0.6'; sb 13.1v; pa 119d.) 43.0' NE of NGC 1808.

83X: Too faint, can only detect an 11 mag star at the galaxy position.

150X: Much improved view - very faint, long slim wisp, with a very small, brighter, stellar nucleus. The nucleus is equal to an 11 mag star for brightness, and this is all that was detected at 83X. The galaxy has a size of 2.0' x 20", major axis is SE - NW, low, even surface brightness.

UA 103 : 05 10.7 -31 36 (12.7v; 3.0' x 2.2'; sb 14.6v)

83X: Requires care, and averted seems to pick "something" there, as an extremely faint, large, hazy glow, probably oval in shape, with a 13 mag field star nearby to the NE.

150X: Slightly improved : extremely faint, oval in shape, 2.5' in size, with a smooth, low surface brightness. The major axis lies E-W. In the wider, general field, there is a 10 mag star to the NW, a small bunching of 13 mag stars to the north, and few other star patterns to use as a guide to the galaxy.

NGC 1851 : Globular Cluster. 05 14.1 -40 03, Magnificent at all magnifications!

8x50 mm finderscope : bright, fuzzy, star.

50X: Very bright, large, round, glow, with a brighter, compact core.

105X: Much improved view beginning to show the magnificence here - tight, bright, irresolved core, within a much extended grainy halo. The outliers in the halo are near resolving quite well.

150X: Brilliant view -At this power the core is still irresolved, but there are at least some twenty 13 mag stars resolving, loosely scattered across the globular glow. The overall size is 8.0' with the core being 30".

NGC 1879 : 05 19.8 -32 09 (12.6v; 2.5' x 1.4'; sb 13.8v; pa 64d.)

83X: Requires care and averted vision - extremely faint, large, oval in shape, very smooth soft glow. There is an 11 mag field star nearby to the NW. 150X: Improved view - extremely faint, 2.0' x 1.0' in size, major axis lies SW - NE, very smooth surface brightness, with an even glow from edge to edge. At this power the galaxy can be held with averted vision continuously. In the wider, general field, there is a light scatter of mostly somewhat bright stars ranging from 11 - 12 mag.

NGC 1891 : 05 21.3 -35 44 (Star field)

This object was listed by Sir John Herschel as a cluster, however, it is considered a "nonexistent" star cluster in most modern catalogues. Herschel's notes describe the object as " A large scattered cluster, which more than fills the field [ ~15.0' in size] Stars 10...12m. Place that of a double star, the chief one."

83X: At Herschels position, I see no apparent cluster, or star group per se, however, there is a very extensive and bright star field here. In this 47' FOV, there are some fifty five stars ranging in brightness from 9 mag to fainter, with many bright 11 mag. The stars show no concentration. There is a rather faint 13 mag double star 3.5' near north of Herschel's position. The wider and much extended star field continues in the directions south to southwest. In all other directions there is a marked drop in the number of bright stars.

150X: Hardly any difference in visual impression. Sometimes, I find that more magnification and the view confined to a smaller size may give the impression that a portion of an extensive star field "appears" like a cluster. However, this is not my impression in this case. In this 20' FOV there are some eighteen stars loosely scattered across the field, and they do not resemble a cluster or star group per se.

Conclusion: I did not find a large, loose star cluster at Herschel's position, but instead found a very extensive and bright star field.

NGC 1963 : Open Cluster. 05 32.2 -36 23

83X: This does not appear as a star cluster per se, but a very obvious and charming collection of stars. There is a long chain of mostly bright stars forming a very pronounced figure 3. Overall, there are nineteen stars involved, ranging from 10 - 12 mag, with a size of 10.0'. In the wider field, there is a bright, 9 mag field star 10.0' to the north showing a strong white/yellow colour; plus, the eye is drawn to the nearby IC 2135 galaxy.

In general, this is an interesting and attractive field, certainly worthy of note. (This object is classed as "nonexistent" in some modern catalogues, however, there are other (reliable) catalogues that equate the N1963 cluster with the star group mentioned above.)

IC 2135 : 05 33.2 -36 24, 12.0' E of NGC 1963.

150X: Obvious, relatively bright, hazy wisp, elongated ESE-WNW, 3.0' x 0.5" in size, with a high surface brightness.

NGC 1989 : 05 34.4 -30 48 (13.1v; 1.4' x 1.0'; sb 13.3v; pa97d.)

83X: Suspected as an extremely faint, small, round, hazy spot, with a possible stellar nucleus. Seen on several occasions with averted vision, when seeing is steady. 150X: Improved view - very faint, small, round, little oval in shape, 40"x 35" in size, with the major axis ESE - WNW. The galaxy has a smooth, low surface brightness, and brightens to a stellar nucleus. Makes a close pair with N1992.

NGC 1992 : 05 34.5 -30 56 (13.6v; 1.1' x 0.7'; sb 13.2v; pa 47d.) 6.2' SSE of NGC 1989.

83X: Too faint. 150X: Barely detectable, but in moments of better seeing, the galaxy appears as an extremely faint, small, round, hazy glow, 30" in size, with a very low, even surface brightness.

NGC 2049 : 05 43.4 -30 06 (12.7v; 2.0' x 1.0'; sb 13.3v; pa 166d.)

83X: Obvious enough with care and averted, very faint, small, round - oval, very soft, dim glow. The galaxy is a little lost in the star field.

150X: Improved view - relatively faint, round, 30" in size, brightening to an almost stellar nucleus. The nucleus is equal to a 13 mag star for brightness.

MCG-5-14-10 : 05 42.9 -29 43 (14.1 mag; 1.1' x 0.8') 21.7' NNW of NGC 2049.

150X: Obvious enough, a soft, very faint, small, round - a little oval shaped glow, 30" in size, with the major axis NE - SW. The galaxy lies against a 13 mag star, and there is a charming, double star, 12 mag, close by to the NW.

MCG-5-14-13 : 05 43.2 -30 30 (13.6P; 1.8' x 1.4') 25.5' S of NGC 2049.

150X: Obvious enough with averted as an extremely faint, large, oval shaped glow, with a very smooth low surface brightness, and a size of 2.0' x 50". The major axis lies nearly E-W.

NGC 2090 : 05 47.0 -34 14 (11.0v; 4.5' x 2.3'; sb 13.4v; pa 13d.)

83X: Easy, bright target - bright, long and broad, with a brighter core.

150X: Improved view - bright, 3.0' x 1.0' in size, high surface brightness, major axis NNE - SSW, with a brighter, very small core. There are three 13 mag field stars off near the N edge. In the general, wider view there is a generous spread of bright 10/11 field stars and then fainter, over a smooth dark background sky. Overall, along with the bright galaxy the view is impressive.

NGC 2188 : 06 10.1 -34 06 (11.6v; 5.5' x 0.8'; sb 13.1v; pa 173d.) Real charmer!

83X: very obvious, bright, long and slim wisp.

150X: Improved view - bright, 4.0' x 40", major axis almost N-S, smooth and even surface brightness. In the general field there are numerous bright stars ranging from 9 - 11 mag with a few fainter. As a lasting impression the view is one of a bright, bold star field with a bright galaxy.

MCG-6-14-9 06 10.9 -33 53 (13.8P; 1.7' x 1.3') 15.7' NE of NGC 2188.

150X: Obvious enough, especially with averted as a relatively faint, relatively small, round, hazy glow, 40" in size, with a smooth surface brightness.