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NGC 6101 (13,718 of 18,816)


oc gc pln bn dn gx gxcl ast aka lost




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NGC 6101

NGC 6101, Dunlop 68, C 1620-720, GCl 40, Bennett 74, Caldwell 107, h 3623, GC 4175

RA: 16h 25m 48.61s
Dec: −72° 12′ 5.6″

Con: Apus
Ch: MSA:1534, U2:454, SA:26

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

(reference key)

Type: globular cluster

Mag: B=10.9, V=10.21

Size: 5′
PA: ?

Historical observations

Dunlop, James (1827)

James Dunlop observed it from Paramatta, New South Wales, and included it as No. 68 in his catalogue of 1827. Using a 9-inch f/12 telescope, he described it as "A pretty large rather faint round nebula, about 3.5-4' diameter, a little brighter in the middle. There is a very small nebula on the N.p. side joining the margin of the large nebula."

John Herschel (1847) Cape Observations

Observed by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "Globular cluster, large, faint, round, very gradually a little brighter in the middle, all resolved into stars 15..18th mag, 4' diam, with stragglers. A delicate and beautiful object." On a second occasion he called it "pretty bright, large, irregularly round, gradually brighter in the middle, resolved into stars 13..16th mag; pretty compressed, diam 5' or 6' by estimation, approx. 50 seconds in RA. A fine object." His final observation was recorded as "faint, large, irregularly round, very gradually brighter in the middle, 7' or 8' diameter, all resolved into stars."

Published comments

Hinks, A.R. (1911)

Hinks, A. R. (1911) On the galactic distribution of gaseous nebulae and of star clusters. MNRAS, 71(8), 693-701.

List 6: "NGC numbers of clusters classed as globular, not in Bailey's catalogue"

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

Melotte, P.J. (1915)

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

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a 10.0 mag globular cluster.

Harris, W.E. (1997)

RA 16 25 48.6 (2000) Dec -72 12 06 Integrated V magnitude 9.16 Central surface brightness, V magnitudes per square arcsecond 20.12 Integrated spectral type F5: Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster .80 Core radius in arcmin 1.15. ["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) ]

Modern observations

Sanford (1989) Observing the Constellations

Sanford calls it a "faint but rich globular cluster ... worth a look with larger amateur instruments (10-inch and up). It is about 3 arcminutes in diameter and begins to resolve well in an 8-inch telescope."

ASV Journal (1971)

ASV Journal Vol 24 No 3 June 1971: "at limit in 4-inch at 64x. Dispersed in 12.5-inch at 150x."

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

Hartung notes: "In fine contrast with a field sown profusely with stars is this rather faint but very rich globular cluster; it is regularly round, rising broadly to the centre, about 3' across with rays of faint stars emerging. Resolution is apparent with 20cm while 10.5cm shows plainly an unresolved haze."

Brian Skiff

15cm - mod br broadly concen cl @ 80x; grainy. 140x: 4' diam w/strong broad concen. brtst *s m13.5-14 res over cottony diffuse ground. a grp of brtr fld *s NW edge suggest res @ lox, but are surely in fgrnd of cl. BS, 24Feb1990, LCO.

Contemporary observations

Auke Slotegraaf

1994 February 21

1994-02-21 03:00 Jonkershoek 11x80 tripod-mounted. This gentle object lies near a bright triangle of stars which aid in locating it. Although faint, it is readily seen when sweeping as a soft, pretty large gentle glow.

1997 April 05

1997 April 05, 01:00 SAST, Coetzenburg, 11x80 tripod-mounted binoculars. Extended circular glow, quite faint, no peaked concentration. Slightly easier than the galaxy NGC 6744. Needs some concentration.

1998 April 23

1998-04-23/24, 11x80 tripod-mounted binoculars, Die Boord. Seeing good, transparency below average, dew. "What a wee one! Exact copy of a 9th magnitud e star. Bright stellar nucleus, with an ever-so-tiny smudge surrounding it, which at times is not apparent - just one of a field of stars. Strange?!"

1993 April 30

30/04/93: Observing with a 6-inch f/8.6 Newtonian, this globular is very challenging in bright moonlight. After careful, sustained study with various eyepieces I picked it out at 65x by tapping the telescope tube. It shows as an extremely faint but surprisingly large nebulous patch which can be held once its position is pinpointed.

Magda Streicher

2010 April 28

Location: Alldays

12-inch f/10 SCT (95x 218x 346)

A relatively large glow is seen with a triangle of three magnitude 12 stars on the north-western edge. A magnitude 8 star situated 5 north is linked in a way together with a string of faint stars. Higher magnification reveals a sandpaper impression with a well outstanding core. The longer I observe the object more faint stars made their presents known. The hazy outer unresolved edge seems to mingle well with the faint field stars.

14 June 2009


RA: 16h25m48s - DEC: -72o12' - Magnitude: 9.2 - Size: 5'

Tel: 12" S/C - 218 - 346x - Date: 14 June 2009 Vis: 5.6

Impressive bright very round glow of intense unresolved star light. With higher power faint stars can be glimpse on its surface which gives a glittering sandpaper effect. The core is compact but not defines against the rest of the globular impression. Faint stars which spray out on the north western periphery that given it a slightly elongated impression.

(no date)

12-inch f/10 SCT (EP: 2-inch 32mm SW 95x 42' fov; 2-inch 14mm UW 218x 23' fov) and 16-inch f/10 SCT (EP: 2-inch SW 32mm 127x 32' fov; 2-inch 14mm UW 290x 17' fov)

Very large, soft round haze of light, gradually very much brighter to the middle. Reveal a granular appearance with very faint stars going out in flimsy flares to the edges. On the northwest edge of this globular cluster a group of four stars that strongly reminds me of the well-known trapezium in the Orion Nebula (290x) can be seen. In the heart of the globular an outstanding pair of stars seen with ease. Fainter stars to the north running out in curls.

Richard Ford

2013 May 12th, Sunday



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 looks like a misty glow of faint light which has the resemblance of an oval out of focus cloud.In appearance NGC 6101's stars are somewhat granular whereby I have noticed that some of the stars in this cluster are just being resolved in the central core of this object.The nucleus of this globular cluster is moderately condensed and that the stars are strongly concentrated towards each other.This globular cluster measures 8.2'x 6.3'.

Favourite lists

Lacaille's catalogue

The Messier objects

Dunlop's catalogue

The Bennett objects

The Caldwell list

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