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NGC 6752 (15,598 of 18,816)

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Cartwheel Globular

NGC 6752, Dunlop 295, Cl Melotte 218, C 1906-600, GCl 108, ESO 141-30, Caldwell 93, Bennett 121, Starfish, Cartwheel Globular, h 3778, GC 4467

RA: 19h 10m 51.78s
Dec: −59° 58′ 54.7″

Con: Pavo
Ch: MSA:1507, U2:435, SA:26

Ref: SIMBAD, SEDS, Corwin (2004)

(reference key)

Type: globular cluster

Mag: B=6.96, V=6.28

Size: 29′
PA: ?

Image gallery

Sketches  (1)

Select a sketch and click the button to view

History and Accurate Positions for the NGC/IC Objects (Corwin 2004)

NGC 6752 may also be NGC 6777, which see.

Historical observations

Dunlop, James (1827)

James Dunlop observed it from Paramatta, New South Wales, and included it as No. 295 in his catalogue of 1827. Using a 9-inch f/12 telescope, he described it as "a pretty large and very bright nebula, 5' or 6' diameter, irregular round fgure, easily resolved into a cluster of small stars, exceedingly compressed at the centre. The bright part at the centre is occasioned by a group of stars of some considerable magnitude when compared with those of the nebula. I am includined to think that this may be two clusters in the same line; the bright part s a little south of the centre of the large nebula." He recorded the cluster on 5 occassions.

John Herschel (1847) Cape Observations

Discovered by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "globular, B, R, p rich, psmbM, 5', stars of 2 sizes, 11-12m and 15..16m, S.p. is an elegant first class double star." On a second occassion he called it "globular, B, rich, psmbM, 7', the stars are of 2 magnitudes, the larger 11m, run out in lines like crooked radii. The smaller, 16m, are massed together in and round the middle." His third observation was recorded as "Globular, B, L, R, rather irregular, stars 11..16m, comes up to a blaze in the middle; semidiameter in RA = 25 seconds; fine; one star 7-8m is S.p. out of the cluster." It was next recorded as "globular, The central mass consists of smaller stars than the outside." The final record reads: "globular, B, irreg R, psvmbM, all resolved; stars 11..15m; diam 5'; has a star 7m 4' south and 14 arcseconds preceding."

Published comments

Burnham's Celestial Handbook

Burnham reports a total diameter of 42', but cautions that "the visual size is about 15' or 16' in most telescopes."

Bailey, S.I. (1908)

"!! globular cluster, fairly condensed"

Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a 7.0 mag globular cluster.

The mean blue magnitude of the 25 brightest stars, excluding the 5 brightest, is 13.36.

Photo index

Photo Index by Jim Lucyk: Burnhams V3 p1356, Ast.Obj.for South.Tel. (Hartung, 1984).

Harris, W.E. (1997)

RA 19 10 51.8 (2000) Dec -59 58 55 Integrated V magnitude 5.40 Central surface brightness, V magnitudes per square arcsecond 15.20 Integrated spectral type F4/5 Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 2.50c: Core radius in arcmin .17. ["Catalog Of Parameters For Milky Way Globular Clusters", compiled by William E. Harris, McMaster University. (Revised: May 15, 1997; from http://www.physics.mcmaster.ca/Globular.html; Harris, W.E. 1996, AJ, 112, 1487) ]

Melotte, P.J. (1915)

A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.

Bailey, S.I. (1913)

Bailey, examining a Bruce plate (Harvard Annals, Vol 72, No 2), describes it as "very remarkable, very bright, globular cluster, much compressed, diameter 20'."

Modern observations

Bennett, Jack

Bennett observed it with a 5-inch short-focus refractor, including it in his list of cometary objects as number 121. His coded description describes it as a circular extended object, fully or partially resolved into stars under a higher magnification or with a larger aperture.

Hartung, E.J. (1968) Astron.Obj.South.Tel

Hartung goes on to described it as "moderately condensed... the central region about 3' wide, and the unusually bright outliers extending over 15', involving an elegant pair (7.7+9.3, 3", 238 ) Many of the brighter stars of the cluster are in curved loops and arms, and look distinctly reddish." He notes that even a 3-inch "shows scattered stars in and around a nebulous haze". The NGC description reads: "bright, very large, irregular figure, clearly resolved into individual stars of magnitudes 11...16". The cluster has a concentration rating of 6.

Williams, Peter F

Peter F. Williams from New South Wales, Australia, calls it a "striking object when viewed through instruments ranging from binoculars to large aperture telescopes. The impression of one globular cluster superposed upon another larger and fainter globular cluster matches well the view presented though my 6-inch f/8 Newtonian. My observing notes for 1977 portray a large, bright globular in which resolution is obvious throughout. Stars within the cluster seem to occupy two distinct levels of brightness, a number of 9th and 10th mag overlying innumerable stars of magnitude 12 and fainter. Outlying members stretch the cluster's diameter to about 10' but the striking feature is a brighter central region 3' across from which stars seem to radiate in a loose spiral pattern. The ease of resolution places NGC 6752 in company with five other great southern globulars: NGC 104, NGC 5139, M4, NGC 6397, and M22. My notes for this object do not, however, make reference to color apart from stating that all stars appeared white in color."

Cozens, Glen

Glen Cozens writes than "An 8-inch shows a half-dozen spidery legs emanating from the cluster's centre and separated by dark patches."

ASV Journal (1971)

ASV Journal Vol 24 No 3 June 1971: "just visible to naked eye. Excellent in telesocpes."

[amastro] NGC 6752 observation

I'll second the motion on NGC 6752. This was the second object I looked at on Tom's and my November 1993 Chile trip (NGC 6397 was first). Herewith notes taken using my 15cm refractor:

15cm - beautimous very rich cluster at 50x, partially resolved with strong background haze. mag. 8 star SSW [4'.1 from center] well within the halo. moderate sharp concentration to conspicuous very small central pip. 80x: halo reaches to mag. 10 star WNW [11'.3 from center, implying an observed diameter of 23']. several fine radial strings of brighter stars coming from center. 140x: 20' diameter, well-resolved overall. the bright star SSW is an unequal double in pa215, delta-mag ~2.5. the central pip is unresolved but irregular in shape, 1' across.

The follow-up: the bright star SSW is CPD-60 7269, which is V=7.4 (my eyeball estimate a bit faint). The companion is listed in the Hipparcos catalogue as being in pa239 (mine off by 20 degrees, not so bad at -60 Dec), and having delta-mag 1.7 (my estimate too large, which is common for visual observation), 2".7 separation. This blue star is obviously very much in the foreground. The fainter star I used to define the edge of the cluster is HD 177694, which has V=9.4 and is a foreground K giant. The surface photometry of Trager et al. shows the cluster is 12' diameter at the V mag. 22/square arcsec isophote, and 29' diameter at the mag. 25 isophote. Thus my observed diameter of about 23' corresponds to something like the mag. 24 isophote, typical of my observations from "true-dark" sites with this telescope. The brightest stars in the cluster are about mag. 10.5 (but B-V = 1.9, fairly red), which is why the cluster appeared partially resolved even at 50x, where I see down to about mag. 13.5. The cluster horizontal branch, where the star-count increase as a function of magnitude makes a sudden leap upward, is at mag. 13.8, which explains both the "strong background haze" comment at 50x (where all those stars would have been just unresolved), and the "well resolved" scene at 140x, where I see down to about mag. 15.3-15.5. The brightest stars and horizontal branch magnitudes are both about 1.2 mag. brighter than for M13, and comparable to M4. But the cluster is far richer than either, and so appears superior. Try to imagine a cluster as large as M4, as bright as M22, and as rich as and structured like M15---will those plane tickets be on LAN Chile or Qantas?!

Brian

Head, Marilyn

"10 Easy Globs!" by Marilyn Head (105 Owen Street, Newton, Wellington, Aotearoa / New Zealand; mhead@clear.net.nz)

To the right and just below Ara lies NGC 6752 in Pavo, my very favourite glob. Nicknamed the "starfish", it is 13,700 l.y. away, has a magnitude of 5.3, a Shapley class of VI and is a stunning view with the bright stellar 'arms', for which it was named, curving away from the centre. As Hartung describes: "a most lovely object".

Brian Skiff

15cm - beautimous vrich cl @ 50x, partially res w/strong bkgrnd haze. m8 * SSW well w/in halo. mod sharp concen to consp vsm cen pip. 80x: halo to m10 * WNW. sev fine radial strings of brtr *s coming from center. 140x: br * SSW is un= dbl, pa215, dm ~2.5. 20' diam. pip is unres but irreg in shape, 1' across. well res.

(unknown)

At magnitude 5.4, this cluster is easily visible to the naked eye under dark skies. Hartung called it "one of the gems of the sky." In a 2-inch refractor it appears bright, with a central condensation larger than Jupiter's disc. A 3-inch telescope shows it as a 3' knot of bright nebulosity surrounded by a faint haze.

With a 6-inch it spans almost 10' across, the outer portions of the cluster being revealed. A 10-inch scope shows it as a "blazing ball of light peppered with faint stars." A 16-inch scope shows countless stars extending nearly 20' across; the stars are so dense toward the centre that they merge into a yellowish nebulous haze.

Contemporary observations

Auke Slotegraaf

1983

Observing from Stellenbosch, 1983, I used a 2-inch refractor and wrote: "A nice globular cluster; bright, central condensation larger than Jupiter's disc. Located near bright star (star brighter than cluster)."

1985

In a 15.5-inch telescope at 220x, this globular cluster is a spectacular object. It has a very small but definite nucleus of tightly concentrated stars, and appears elongated northeast-southwest. To the south and west of the nucleus is a bright star. The cluster is very well resolved, except for the nucleus, which appears banana-shaped. There are many obvious star chains which seem to start near the nucleus and loop outwards. Particularly noteworthy are two chains, a large one on the southeast and a tiny one to the northeast. Each chain forms a complete loop, (the smaller one is more clear), enclosing a dark patch on the inside of a loop, rather like a necklace of pearls. This cluster is best observed slowly, letting your eye play with the shapes that the stars seem to trace out across the face of this globular.

1997 April 05

1997 April 05, 01:00 SAST, 11x80 tripod-mounted binoculars. Extremely bright globular cluster, dense button nucleus with fringe seen with averted vision. Right next to a bright star.

1997 September 03

1997 Sept 03: 11x80 tripod-mounted. 23:00 SAST. Jonkershoek. Bright, round blaze of light, very broad centre, outer fringe much less prominent. Much brighter star to the south-west. This star makes the cluster look almost bi-nucleat.

1997 September 20

1997-09-20, Sutherland (Karoo), SAAO plateau. 11x80 tripod-mounted binoculars. Skies excellent. "Glorious bright blaze, spilling light over an area 4 arcmin in diameter. About 90 arcsec away is a 7th mag star."

1997 November 3

1997 November 3/4, Jonkershoek. 11x80 tripod-mounted, seeing 4, transparency 3, darkness 3, lim mag = 6.0 (naked eye, pole) "Massively bright globular, with a bright star south-west; with averted vision, its glow extends to perhaps 13 arcmin."

Magda Streicher

(no date)

Location: Campsite (South 23 16 East 29 26).

Sky conditions: Clear, steadiness good.

Instrument: Meade 8 inch, Super wide-angle, 18mm eyepiece; 36.2' fov

DSO Report N

Large, bright very nice clear even, irregular globular cluster, little condensed with a bright core. Pinpoint stars running out in trails and forming even a nice circle to one end. Very bright star embedded to the southwest. Maybe up to 20 arc minutes.

(no date)

12-inch f/10 SCT

Lovely, partly resolved with a small busy core with faint stars spraying out into the field of view. Very stringy on the edges. A 7Magnitude whitish star is situated in the SW part of the cluster. The cluster members is mingle well with the SW star field. (Mag 5.4; size 20.0'; brightest stars 10 mag.)

(no date)

12-inch f/10 SCT (EP: 2-inch 32mm SW 95x 42' fov; 2-inch 14mm UW 218x 23' fov)

Also known as the "Starfish" it displays a large, bright and elongated in a northeast to southwest direction. It appears as a well-resolved cluster with a small, bright and oblong condensed core. Pinpoint stars running out in trails and loops towards the edges into the field of view. A bright outstanding circle of stars situated on the southeast edge. An eye catching whitish 6.7 magnitude star is imbedded in the southern outskirts of the globular. Our deep sky director has this to say about NGC 6752; "This cluster is best observed slowly, letting your eye play with the shapes that the stars seem to trace out across the face of this globular".

2006 May 30

Pietersburg

16-inch f/10 SCT (127x, 290x)

This is my cartwheel globular very small core from where stars spray out in sircles just like a wheel. Outstanding.

Carol Botha

2010- 07- 17

Location: Betty's Bay

Time: 23:30

Telescope: 12" Dobsonian f4,9. Eyepiece 15mm. FOV- 36'

Sky conditions: Seeing 3/5 (gibbous Moon)

Apparent size:14'x12'

Actual dimensions:20.4 x 20.4 Cartes Du Ciel

Object description:

Globular cluster in Pavo

Small dense nucleus surrounded by irregular triangle-shaped smooth nebulosity.

A faint string of stars from E-, a loop of stars NW of the nucleus and one very faint and one very bright star to the S.

In the eyepiece it looks like a fighter jet bursting through a cloud.

Richard Ford

2015 June, 20th

Location:Perdeberg.

Time:8:40pm.

Sky Conditions:The fainter parts of the Milky Way are barely visible.Haziness only visible on the horizon.Atmosphere stable with little interference.

Instrument:12-inch Dobsonian.

In this globular cluster the stars are well resolved into hundreds to thousands of stars in a large agglomeration and that the stars in NGC 6752 are spherically concentrated towards each other.This is a fairly condensed globular cluster and that the nucleus of this cluster shines like an out of focus mist of light.This globular cluster measures 6.1'x 4.3'.Chart No.280,NSOG Vol.3.

Favourite lists

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