47 Tucanae (NGC 104)

47 Tucanae
47 Tucanae: Globular cluster in Toucan; Takahashi TOA 150/1100 APO refrcktor at f/7.27 with TOA-67 field flattener; SBIG STL-11000M; Astro-Physics 1200GTO; 16x5 min; Namibia, Tivoli Southern Sky Guest Farm, 1360 m ASL; © 29. 8. 2016 Manuel Jung [45]

History

This object was first noted, but as a star and not a cluster in Bayer's Uranometria, which was published in 1603. In 1751-1752 the French astronomer Nicolas-Louis de Lacaille was on an expedition on the Cape of Good Hope, charting the southern constellations and observed the cluster with a 1/2-inch telescope at 8x magnification. He logged it as Lac I-1 and noted that it appeared «like the nucleus of a fairly bright comet». In Johann Bode's Uranographia of 1801 the «star» is listed as «47 Tucanae» originating from Bode's extension of Flamsteed numbers to the southern constellations. [364]

On 1 August 1826 Scottish astronomer James Dunlop observed with his 9-inch speculum reflector at his house in Parramatta in New South Wales. He logged the cluster as D 18 and noted: «(47 Toucan, Bode) this is a beautiful large round nebula, about 8' diameter, very gradually condensed to the centre. This beautiful globe of light is easily resolved into stars of a dusky colour. The compression to the centre is very great, and the stars are considerably scattered south preceding and north following.» [50]

John Herschel observing with his 18.25-inch reflector from Feldhausen, South Africa logged for h2322 the first note during sweep 441 (11 April 1834): «The great cluster preceding the Nubecula Minor. Estimated dia 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.)»

On 12 August 1834 Herschel wrote «A most glorious cluster. The stars are equal, 14th mag., immensely numerous and compressed. Its last outliers extend to a distance of 2 min, 16 sec 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 Herschel 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 sec 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.»

Herschels final recording was on 5 Nov 1836: «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" dia 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.» [11]

Physical Properties

Revised+Historic NGC/IC Version 22/9, © 2022 Dr. Wolfgang Steinicke [277]
Designation NGC 104
Type GCL (III)
Right Ascension (J2000.0) 00h 24m 05.2s
Declination (J2000.0) -72° 04' 49"
Diameter 50 arcmin
Visual magnitude 4.0 mag
Metric Distance 4.500 kpc
Identification, Remarks h 2322; GC 52; GCL 1; ESO 50-SC9; 47 Tuc

Finder Chart

The globular cluster NGC 104 can be found in the constellation Tucana and is visible to the naked eye west of the Small Magellanic Cloud. Unfortunately it is not visible from Europe. On 28 September it in opposition with the Sun and is therefore highest in the sky at local midnight.

Finder Chart 47 Tucanae (NGC 104)
47 Tucanae (NGC 104) in constellation Tucana. Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. [149, 160]

Objects Within a Radius of 30°

References

  • [11] «Results of astronomical observations made during the years 1834, 5, 6, 7, 8, at the Cape of Good Hope ... : being the completion of a telescopic survey of the whole surface of the visible heavens, commenced in 1825» Herschel, John F. W.; London : published by Smith, Elder and Co., 1847; DOI:10.3931/e-rara-22242
  • [45] Astro-, Landschafts- und Reisefotografie sowie Teleskopbau, Manuel Jung; sternklar.ch
  • [50] «VIII. A catalogue of nebulæ and clusters of stars in the southern hemisphere, observed at Paramatta in New South Wales, by James Dunlop, Esq. In a letter addressed to Sir Thomas Makdougall Brisbane, Bart. K. C. B. late Governor of New South Wales. Presented to the Royal Society by John Frederick William Herschel, Esq. Vice President» James Dunlop;Philosophical Transactions of the Royal Society of London, Volume 118, pages 113-151, published 1 January 1828; DOI:10.1098/rstl.1828.0010
  • [149] SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
  • [160] The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
  • [277] «Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; klima-luft.de/steinicke (2021-02-17)
  • [364] Steve Gottlieb's NGC Notes; astronomy-mall.com/Adventures.In.Deep.Space/steve.ngc.htm