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47 Tuc

Lacaille I.1, Dunlop 18, NGC 104, Cl Melotte 1, C 0021-723, GCl 1, Bennett 2, Caldwell 106, 47 Tuc, h 2322, GC 52

RA: 00h 24m 5.67s
Dec: −72° 04′ 52.6″

Con: Tucana
Ch: MSA:502, U2:440, SA:24

Ref: SIMBAD, Archinal&Hynes (2003), SEDS

(reference key)

Type: globular cluster

Mag: B=5.78, V=4.91

Size: 50′
PA: ?

Image gallery

Sketches  (3)

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Photos  (12)

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Remarks

At magnitude 4.0, this cluster is visible to the naked eye as a blurred star about 2.5 degrees west of the Small Magellanic Cloud. A 4-inch telescope achieves partial resolution of the cluster, since the brightest stars are magnitude 11.5.

Historical observations

Lacaille (1755)

This spectacular globular cluster was discovered by Lacaille and included in his 1755 catalogue as Class I No. 1. In his half-an-inch 8x telescope he saw it as being "like the nucleus of a fairly bright comet."

James Dunlop (1828)

Dunlop, J. (1828) A Catalogue of Nebulae and Clusters of Stars in the Southern Hemisphere, Observed at Paramatta in New South Wales. Phil. Trans. Roy. Soc., 118, 113-151. [1828RSPT..118..113D]

James Dunlop observed it from Paramatta, New South Wales, and included it as No. 18 in his catalogue of 1827. Using a 9-inch f/12 telescope, he described it as "a beautiful large round nebula, about 8' diameter, very gradually condensed to the centre. This beautiful globe of light is easily resolvable into stars of a dusky colour. The compression to the centre is very great, and the stars are considerably scattered S.p. and N.f."

John Herschel

Sir John Herschel observed it frequently during his stay at the Cape of Good Hope. He used an 18-inch f/13 speculum telescope, and observed it for the first time on 11 April 1834. On that occasion he wrote of it as "the great cluster preceding the Nubecula Minor. Estimated diameter of the denser portion 5'; of the whole (not, however, including loose stragglers) 8'. Stars 14..16 mag. and one of 12th mag N.p. the centre. Excessively compressed. (N.B. In a sweep below the pole, when of course owing to the low altitude much of the light was lost.)" His observations of 12 August 1834 read: "A most glorious cluster. The stars are equal, 14th mag., immensely numerous and compressed. Its last outliers extend to a distance of 2 minutes, 16 seconds in RA from the centre. It is compressed to a blaze of light at the centre, the diameter of the more compressed part being 30 arcsec in RA. It is at first very gradual, then pretty suddenly very much brighter in the middle. It is completely insulated. After it has passed, the ground of the sky is perfectly black throughout the whole breadth of the sweep. There is a double star 11th mag. preceding the centre (Pos. 226.5 - 6.5 arcsec in RA from centre of neb.)" On 21 September 1835 he wrote: "Fills the field with its stragglers, condensation in three distinct stages, first very gradually, next pretty suddenly, and finally very suddenly very much brighter in the middle up to a central blaze whose diameter in RA is 13.5 seconds and whose colour is ruddy or orange-yellow, which contrasts evidently with the white light of the rest. The stars are all nearly equal (12..14 mag). A stupendous object." His final record of the object was made on 5 November 1836 when he called it "A most magnificent globular cluster. It fills the field with its outskirts, but within its more compressed part, I can insulate a tolerably defined circular space of 90 arcsec diameter wherein the compression is much more decided and the stars seem to run together; and this part I think has a pale pinkish or rose-colour." He sketched the cluster, showing its appearance "as seen on a great many other occasions." He noted that "the contrast between the rose-coloured light of the interior and the white of the exterior portions cannot, of course, be represented in an engraving, but of the phenomenon itself, I have no doubt. The double star on the S.p. edge of the more condensed portion has probably no connexion with the cluster." Referring to its overall shape, he notes "its figure is round, and not elliptic - (at least not so elliptic) as described and figured by Mr. Dunlop."

Published comments

NGC/IC Dreyer (1888, 1895, 1908)

The NGC description reads: "A most splendid object! very bright, very large, very much compressed in the middle."

Agnes Clerke

Agnes Clerke wrote that "the sheeny radiance of this exquisite object appeared of uniform quality from centre to circumference . . . Perhaps no other cluster exhibits an equal degree of compression . . . The blankness of the surrounding sky renders 47 all the more obvious to unaided sight; it was, indeed, for several nights . . . mistaken by Humboldt for a comet."

Burnham's Celestial Handbook

Burnham writes: "In larger instruments the cluster becomes a shimmering globe of thousands of star points, crowding toward a rich central blaze. The diameter is about 25' visually, but on the best photographic plates the full size is close to 45'." The average magnitude of the brightest 25 stars is 13.4, and it has a concentration rating of 3.

Bailey, S.I. (1908)

"Diam 30' !!! globular cluster, condensed."

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

Remarks, p.216: "Situated near the SMC, but apparently having no connection with it. One of the finest of the globular clusters. The stars appear to belong to two groups, as regards magnitudes, one having stars from the 13th to the 15th magnitude, and the other of about the 17th magnitude. The distribution of the stars of both grops appears to be similar. The number of stars in this lcuster has been counted on a Bruce plate having a long exposure, except near the centre, where the images coalsecs and are burned out. On the assumption that the law of distribution is the same near the centre as near the margin, the number of stars in the cluster, as derived from the count, is 9500. Six of these are known to be variable. The only close rival to this cluster is omega Centauri, NGC 5139, but 47 Tucanae is much more condensed in the centre."

Melotte, P.J. (1915)

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

Doig, P. (1925)

Journal BAA, 36(3), Dec, p91

This splendid globular cluster is, ... nearlyhalf a degree diameter .. the redder centre metioned in Webb is perhaps due to a central condensation of red supergiant stars of large mass..."

Sulentic & Tifft (1973)

(Sulentic and Tifft 1973) notes that this is a 4.5 mag globular cluster.

Laustsen, S., Madsen, C. & West, R.M. (1987)

Exploring the Southern Sky: A pictorial atlas from the European Southern Observatory. Springer-Verlag.

Scanned image on disk. <1987EtSS.........0L>, plate 175

Harris, W.E. (1997)

RA 00 24 05.2 (2000) Dec -72 04 51 Integrated V magnitude 3.95 Central surface brightness, V magnitudes per square arcsecond 14.43 Integrated spectral type G4 Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 2.04 Core radius in arcmin .37. ["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) ]

Also see: Harris, W.E., Hesser, J.E. & van den Berg, D.A. (1984) Probing 47 Tucanae. Sky & Telescope, Sep, 219.

Photo index

by Jim Lucyk: Sky & Tel. 2/75 p80, Sky & Tel. 3/86 p239, Sky & Tel. 4/76 p233, Sky & Tel. 4/81 p341, Sky & Tel. 8/81 p112, Sky & Tel. 9/84 p219, Sky & Tel. 10/74 p225, Astronomy mag. 10/86 p110, Burnhams V3 p1911.

Modern observations

ASV Journal (1971)

ASV Journal, Vol 24, No 3, June 1971: "hazy to naked eye, good in binoculars, superb in telescope."

Harrington, Phil (1986)

Harrington, P. (1986) More globulars for observers. Sky & Telescope, Sep, 310.

".. visible to the naked eye as a 4th mag star several degrees west of the SMC ... a 10-inch telescope will show countless stars spread across its nearly half-degree diameter, and many stars can be resolved with a 4-inch aperture."

Brian Skiff

= 47 Tuc

QBS: gc N 121 @ 35' in pa 21.

br * has V=10.26, B8III, non-member, see MNRAS 120,473.

15cm - fabulous obj w/unique form. 40' diam, reaching halfway to N121 to N, partially res even @ 30x. sev m9-11 fld *s sup, incl one of m10.5 (?) 3' SW of nuc. main body 20' diam, core 6' diam. mod even concen up to here. nuc is sharply def disk 2' across, reaching 1/3 way to * SW of center. nuc has no concen w/in it, but hix shows brtr & dkr areas in grainy patch. def in "well-res" category, thousands of *s res. outmost regions have wedges of ill-def blank areas and arms of *s. BS, 17Feb1990, LCO.

- 1990 descr good. br * nr SW edge of nuclear disk is V ~11.5. direct vis best for core, and this shows remarkable sparkling of brtr *s spilling out of disk. disk appearance of nuc goes away toward 295x, even 165x shows smoother transition to inner halo. BS, 8Nov1993, LCO.

Danie L. Cronje

1982, 10x50

Danie Cronje, observing with 10x50 binoculars, calls it "large, very bright. Very bright, round core."

Contemporary observations

Auke Slotegraaf

1982

In a 15.5-inch reflector, the first impression of the cluster is simply the overwhelming multitude of stars, and then the very tight, knotted nucleus. Studying the object, it seems to be divided into three layers: (1) there is the central compact core with some stars resolved, then (2) a surrounding halo, twice as wide as the core, and then (3) a completely dissociated matte sprinkling of stars. There are also a number of foreground stars which seem to lie over the globular, the most prominent one lies southeast of the cluster, just outside the fringe, and appears red. Observing at 200x, the cluster exhibits two interesting features. The most prominent is a lesion on the eastern side of the nucleus. This is a dark gap, about a half to a third of the width of the core, extending west-east across the core, causing it to look like a Pac-Man. Also present are conspicuous streamers of stars leading from the nucleus into the 2nd zone. There are at least four of these streamers, two starting from the lesion, and two originating directly opposite. At 260x, the dark gap appears less conspicuous, although the gap itself seems to have a chain of stars lying on its southern side. Upon close examination, however, the dark gap seems to extend right across the core, dividing it into two uneven halves, the smaller half being to the south and about a third of the total area in size.

1995

A 10-inch f/5 reflector at 30x shows this incredible object as an innumerable host of bright points gathered up into a round blaze of unresolved stars in the centre. The central blaze looks like a bright button. In the wide-field eyepiece, many unevenly distributed field stars are visible, and looking towards the cluster, the star density gradually increases, and then all of a sudden the stars gather into a nucleus. This nucleus is a very prominent feature and it draws the eyes attention right away; with the result that you see the outer region as a widely scattered starfield with a bright disk in the centre which glows warmly with a slight tinge of yellow; if you avert your vision onto one of the bright field stars, the outer regions fill up with stars, becoming less resolvable, the whole looking like Omega Centauri.

1997 September 20

1997-09-20, Sutherland (Karoo), SAAO plateau. 11x80 tripod-mounted binoculars. Skies excellent.

Breath-taking! Nucleus 1.5 arcmin wide, a perfectly round bright disc; with a round soft halo at least 12 arcmin wide.

2002 July 01

Stellenbosch (Paradyskloof Rifle Range)

11x80 tripod-mounted binoculars (12.5-mm aperture mask)

Conditions: Dark moon. Slight easterly breeze. NELM approx 5.5 at the pole. Dew.

Brilliant blaze, like a comet. Through the 12.5mm mask, a bright comet. Lacaille's description: my impression confirms his description.

Magda Streicher

1997 Nov 20, Pietersburg, 12-inch SCT

Observer: Magda Streicher.

Location: Pietersburg. ( South 23 53. East 29 28).

Sky conditions: Very good 7 magnitude.

Instrument: Meade 12 inch (Eyepiece super 40mm).

Date: 20 November 1997.

Field of view: 52.7 arc minutes.

What an exellent beautiful globular cluster! Very large compressed and bright towards the middle. It resembles a soft light embedded in a haze of crowded faint and brighter stars going out to the far edges. Two bright stars along the sides round it off beautifully.

(no date)

8-inch f/10 SCT (EP: 1.25-inch 26mm SP 77x 41' fov; 1.25-inch 18mm SW 111x 36' fov) and 12-inch f/10 SCT (EP: 2-inch 40mm SW 76x 53' fov; 2-inch 14mm UW 218x 23' fov)

What a breath-taking excellent globular cluster! Very large, round sphere with crowded stars working up to a sudden bright, unresolved dense centre which could well be up to 3' arc minutes in size. The prominent bright blazing centre works its way out with scores of glittering stars spraying into the star-field (218x). A swarming three-dimensional spectacular! Two bright stars along the western and eastern side rounds it off beautifully. About 21' arc minutes to the north of NGC 104 is the pretty small open cluster NGC 121 with a 10.6 magnitude. (Magnitude 3.8v; size 30.9'; brightest stars = 11.7v)

Carol Botha

Kerneels Mulder

2009 January 20

Date and Time: 20 January 2009, 21:20
Location: Prince Albert (Western Cape, South Africa).
Instrument: Orion XT10 10" f/4.7 Dobsonian Reflector
Eyepieces: 8mm (150x, 24′ FOV), 10mm (120x, 26′ FOV), 25mm (48x, 1� FOV)
Sky Conditions: Clear. Seeing: 6/10. Transparency: Good
Slightly windy

Very easy to locate. Appears as a faint star just below the SMC.

48x: Large globular cluster with very bright dense core. Very concentrated towards the center. Brightness fades gradually from core outwards toward edges. Granular in appearance with hundreds of stars in the outer region resolved. Size is estimated at approx 25′.

47 Tucanae appears to be located within a triangle asterism formed by 3 stars in the surrounding area (WNW, NE, SSE). Next to the central region (S) a prominent star can be seen.

150x: Central region very well resolved but remains granular and brighter than surrounding area. Thousands of stars appearing like grains of sand fill the entire FOV. Too many to count.

Chris Vermeulen

2007/8/18, 21h09

Sky Conditions: Clear

Quality of Observation: Very Good

Bill Hollenbach's Pad

6" Dobsonian, 10mm Eyepiece

One of the most spectacular globular clusters to view is Tuc 47 (NGC 104). Located in Tucana Tuc 47's only rival is Omega Centauri (NGC 5139). Visible to the naked eye it appears as nothing more than a small fuzzy-like star. However at high magnification (10mm eyepiece) the splendour of Tuc 47 really is visible. With a very dense core, it shines very bright as the stars are very closely compressed together. Very few stars surround the object itself, and even those on the outer edges are also close-knit to the object itself, and therefore not giving g any impression of a cloud-like appearance on it s edges.

Richard Ford

2013 November 3rd, Sunday

Location:Perdeberg.

Time:2:10am.

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.

This globular cluster has the shape of a oval mop that looks like a fluffy snowball and that the stars in this cluster are well resolved.The stars in this cluster are spherically concentrated towards each other.The nucleus of this cluster is centrally condensed.This globular cluster measures 9.2'x 7.6'.

2010 February 14,Sunday

Location:Koornlandskloof.

Instrument:12"Dobsonian Reflector Telescope.

Sky Conditions:Dark moon and stars magnitude 6 and fainter are barely visible with the naked eye.

Transparency of the Sky:The most clear sky possible.

Seeing:Excellent clean sky,limited star flickering and brilliant objects.

Limiting Magnitude:6.5.

Size in Arc Minutes:11.2'.

A stunning sight in a medium to large aperture size telescope under very dark skies.

This globular cluster is large as far as most globular clusters are concerned.The bright individual stars in this globular cluster is very well resolved into bright individual stars radiating slightly away from each other.The stars in this globular cluster is spherically concentrated towards each other in a bright halo.All over this cluster there are bright chains of stars spherically concentrated towards each other.On the outskirts of this globular cluster I have found prominent empty spaces.

Andre de la Porte

2011 December 04, Sunday

Location: Riviera, Pretoria

Time: 20:00-20:50

Telescope: Orion 10 In Dob

Limiting magnitude: 4.5

Sky conditions: Generally good with some passing clouds influencing the observation

(25mm, 48x) The globular cluster appears as a faint patch of fuzzy light. In a 25mm eyepiece it is mainly the central core that is visible.

(10mm, 120x) The globular cluster appears as a spread out ball of tightly packed stars. Central part appears markedly brighter. Under light polluted skies there is a limit to the outlying areas that can be seen. Brightness and amounts of stars drops off markedly towards the outside.

Pierre de Villiers

2016 February 04, Thursday

Location: Bonnievale SSP (Night Sky Caravan Park)

Telescope: Skywatcher 200-mm f/5, Delos 8-mm (0.57-deg fov)

47 Tuc is a spectacular globular cluster east of SMC. Dense central part, decreasing outward. Colour white/yellow. Size 50-arcmin, core 10-arcmin; m = 4.

miguel5526

2017 November 28, Tuesday

Location: Buenos Aires Argentina

Time: 20:30

Telescope: sw heritage 130/650

Limiting magnitude:13

Sky conditions:4

Favourite lists

Lacaille's catalogue

The Messier objects

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