Globular Cluster NGC 6397

NGC 6397
NGC 6397: Image taken with ESA's Euclid space telescope [730]

History

This globular cluster was discovered by French astronomer Nicolas-Louis de Lacaille (also: de la Caille) in 1751-1752 with a 1/2" telescope at 8x, during his expedition to the Cape of Good Hope. He listed it as Lac III-11 and noted: «Small star involved in a nebulosity.» [8]

Scottish astronomer James Dunlop independently found this globular on 28 June 1826 using his 9-ich speculum reflector. He made four observations, listed it as Δ 366 and noted: «A pretty large nebula, extended nearly in the parallel of the equator, brightest and broadest in the middle; a group of very small stars in the middle give it the appearance of a nucleus, but they are not connected with the nebula, but are similar to other small stars in this place which are arranged in groups. The nebula is resolvable into stars.» [50]

John Herschel listed the cluster as h 3692. He observed it three times. His first observation was on 8 July 1834 (sweep 468) and he noted: «Globular cluster; fine; large; bright; round; gradually brighter to the middle; not very compressed; 5' diameter, but stragglers extend a great way. In the middle is a more compact group of much smaller stars. The stars at circumference are larger than in the middle; at north following border is a double star.» [11]

Physical Properties

Revised+Historic NGC/IC Version 22/9, © 2022 Dr. Wolfgang Steinicke [277]
DesignationNGC 6397
TypeGCL (IX)
Right Ascension (J2000.0)17h 40m 41.3s
Declination (J2000.0)-53° 40' 23"
Diameter31 arcmin
Visual magnitude5.3 mag
Metric Distance2.300 kpc
Dreyer Descriptionglobular, B, vL, Ri, st 13
Identification, Remarksh 3692; GC 4311; GCL 74; ESO 181-SC4

Finder Chart

The globular cluster NGC 6397 is located in the constellation Ara. Unfortunately it is not visible from Europe. On 17 June it in opposition with the Sun and is therefore highest in the sky at local midnight.

Ara: Globular Cluster NGC 6397
Finder Chart Globular Cluster NGC 6397
never
21:56 | -10.5°
always
Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. Times are shown for timezone UTC, Latitude 46.7996°, Longitude 8.23225°, Horizon height 5°, Date 2025-07-11. [149, 160]

Objects Within a Radius of 20°

References

  • [8] Sur les Étoiles Néebuleuses Du Ciel Austral; l'Abbe de la Caille; Mémoires de l'Académie Royale Des Sciences, 1755, page 194; gallica.bnf.fr/ark:/12148/bpt6k35533
  • [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
  • [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; Dr. Wolfgang Steinicke; klima-luft.de/steinicke; 2021-02-17
  • [730] Euclid’s view of globular cluster NGC 6397; esa.int/Science_Exploration/Space_Science/Euclid/Euclid_s_view_of_globular_cluster_NGC_6397; 2025-07-02