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RA: 13h 46m 26.58s
Dec: −51° 22′ 24.5″
Ch: MSA:971, U2:430, SA:21
Ref: SIMBAD, SEDS
Type: globular cluster
Mag: B=?, V=7.4
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James Dunlop discovered this cluster from Paramatta, New South Wales, and included it as No. 388 in his catalogue of 1827. Using a 9-inch f/12 telescope, he described it as "a bright exceedingly well-defined rather elliptical nebula, about 1' diameter, exceedingly condensed almost to the very edge, and gradually a little brighter to the centre. This is about 6' north of M Centauri - I have a strong suspicion that this is resolvable into stars."
Observed by John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "very bright; gradually much brighter to the middle; 2.5' or 3' diameter; resolved into 15th mag stars; has one star 12th mag S.f.; the centre near the edge. It is in the field with Brisbane 4618 a star of 6th mag." His second observation records it as "bright; round; very gradually brighter to the middle; resolved; diam. 2'; stars of 16th mag; a bright star 7th mag in field."
The NGC records it as "very bright, pretty large, round, clearly resolved into stars of 15th mag."
Burnham calls this a 9th mag globular cluster in Centaurus, 4' diameter, "very bright,pretty large, round, stars of 14th mag and fainter."
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
"! globular cluster, fairly condensed"
Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.
From: "Neat Southern Planetaries - III."
NGC 5286/ 388(13465-5122) is a Globular Star Cluster some 0.8O SSW of NGC 5307. It was first observed by James Dunlop from Parramatta Observatory in May 1827. Easily found on top of M Centauri (Mag. 7.6), it is an easy object for a 7.5cm., though a 15 cm. in needed to start to reveal the internal stars. Appearance-wise, this is a very condensed - given as Shapley class of Type III, though most of the latest data suggest it is Type V (As in Sky Catalogue 2000.0). The globular subtends and angle of some 10'min.arc, and is slightly ovoid at position angle 170O.
Both AOST1&2 state that the distance is some 9.0 kpc., though more recent measures suggest that it is perhaps closer to 10 kpc.. Sky Catalogue 2000.0 states the distance is 8.9 kpc. For the larger Dob's note the 15th magnitude red star within the GSC some two-thirds the way out from the centre of the globular.
M Centauri / HDO 225 (SAO 241157) (13467-5126) is a bright yellow 4.7 magnitude star which is also the double star some 4.5'min.arc. SE. This pair is tough, though it can be seen easily in a 20cm. using high power. Magnitudes are 4.7 and 11.0, separated by about 4" sec.arc at PA 54O. The colour of the star I observed as yellow and white. The primary is a known spectroscopic binary (Boss 3547) with a period of 437.0 days. Discovered in 1922, the first orbital parameters were determined by Jones in 1927. (Published 1928). Velocities vary by ±5 km.sec-1, and is a likely candidate. for future interferometry measures. True separation between the stars is 73 million kilometres - or about half the distance between the Sun and the Earth. Little observational data has been achieved in the last six decades.
From NGC 5307, 1O north-west, is a trapezium shaped set of 5th to 8th magnitude stars. There is also two additional stars to the north. Using a power of 60X or so, in a small telescope, this asterism makes a very pretty field. The region, to about 1O, also contains a number of 'S' spectral class stars. Spectral analysis of the all stars indicate high interstellar absorption.
The RNGC (Sulentic and Tifft 1973) notes that this is a 9.5 mag globular cluster.
RA 13 46 26.5 (2000) Dec -51 22 24 Integrated V magnitude 7.34 Central surface brightness, V magnitudes per square arcsecond 16.07 Integrated spectral type F5 Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 1.46 Core radius in arcmin .29. ["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) ]
Hartung writes that "this bright globular cluster shows faint star points with a four-inch. It is a fine object about 2.5' across with many scattered outliers and broad concentration to the centre, but is far outshone by a bright deep yellow star 4' N.p.; this is the spectroscopic binary M Centaurii..."
Bennett observed it with a 5-inch short-focus refractor, including it in his list of cometary objects as number 64.
QBS: M Cen 3'.9 SE (Harris et al 1976: V=4.64/0.94). m12 * ~40" NE.
15cm - fairly br cl NW of yelsh M Cen, vfine grained @ 80x. 195x: 3' diam,
reaching halfway to M Cen. strong even concen to 45" core; no sharp nuc,
although a * nr center occas stands out. m12 * in NE side well w/in brtr
part. cl *s m14.2+. BS, 23Feb1990, LCO.
A two-inch refractor at 20x shows it as a bright, very small, almost point-like object. It appears evenly illuminated having no distinct point-like nucleus. It lies at the tip of a Scorpio-like asterism. The tip of the asterism is marked by a pretty bright reddish star, and the globular lies to its north north-west.
Observing with a 6-inch f/8.6 Newtonian at 52x the cluster appears bright, regularly round and much compressed. The bright orange M Cen lies to the south-east and makes an attractive, contrasting companion. Within the cluster on the edge lies a 10m star, which is seen at 144x but not at 52x. At 325x I suspect it is resolvable, the cluster appearing mottled. I also suspect another star in the outer regions. It seems irregular in shape at this power.
1994-01-19: 11x80's, The Boord, 02:00 SAST Always a pleasant sight: the bright M Cen with its ghostly after-image. Breathtaking contrast with Omega Cen, just over a field away.
1995-05-28: 11x80.Technopark. 20:15 SAST. Hazy sky, thin clouds. A quite surprising little object. Easy to miss if you casually sweep the area. A slightly closer look at the star M Cen shows that it has a pretty large round hazy companion, which is the cluster. Quite a surprising object for binoculars.
Location: Camp Site: ( South 23 16 East 29 26 )
Sky conditions: clear fair about 6 magnitude.
Instrument: 8 inch Meade ( super wide-angle 18 mm. Eyepiece ).
Date: April 1997.
Bright round large globular cluster with nice pinpoint stars visible. The dense middle is a bit hazy with random outliers. The bright orange star (M. Centaurus) to the edge standing out beautifully.
12-inch f/10 SCT (EP: 2-inch 32mm SW 95x 42' fov; 2-inch 14mm UW 218x 23' fov)
Bright round large globular cluster with nice faint pinpoint stars randomly visible. Displays a very dense and large core, which is slightly hazier towards the edges with stars forming random outliers (95x). It shows an elongated impression in a northeast to southwest direction. The bright orange star (M Centaurae) 4.56 magnitude is 5' arc minutes to the south of this cluster and overwhelms the field of view. Few stars can be seen in the west of the field of view.
Sky Conditions:The fainter parts of the Milky Way are barely visible.Haziness only visible on the horizon.Atmosphere stable with little interference.
This globular cluster has the shape of a compact bright mottled snowball where all the stars in this cluster are partially resolved.This cluster is strongly condensed as a halo of soft white light.The central nucleus of NGC 5286 is very compact.This globular cluster measures 4.3'x 3.5'.Chart No.81,NSOG Vol.3.
12-inch Dobsonian f5 (EP: 20mm UW, 7mm UW)
Conditions: The fainter parts of the Milky Way are barely visible. Haziness only visible on the horizon. Atmosphere stable with little interference. Limiting Magnitude: 4.9.
NGC 5286 is an extremely bright globular cluster, oval in shape, with a mottled appearance as a compact snowball. It is easy to observe in city skies. In the central structure of this cluster individual stars are partially resolved. The stars are centrally concentrated towards the nucleus. The nucleus measures 12' and the halo measures 7'.
The Messier objects
The Bennett objects
The Caldwell list
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