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RA: 17h 36m 17.05s
Dec: −44° 44′ 5.8″
Ch: MSA:1458, U2:408, SA:22
Ref: SIMBAD, SEDS
Type: globular cluster
Mag: B=7.4, V=6.72
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James Dunlop discovered this object from Paramatta, New South Wales, and included it as No. 457 in his catalogue of 1827. Using a 9-inch f/12 telescope, he described it as "a beautiful round nebula, about 5' diameter, with a bright round well-defined disk or nucleus, about 15 arcseconds diameter, exactly in the centre; this has the appearance of a planet surrounded by an extremely faint diluted atmosphere; there is a small star involved in the faint atmosphere: the atmosphere is at least 6' diameter."
Observed by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "globular, vB, R, first p g, then psvmbM, 4' diam, easily resolved with left eye into stars 17th m, more difficulty with right eye into 18m, ecessively close and comp; shading off insensibly in borders into the general ground of the heavens." On a second occassion he called it "globular, vB, R, at first pg, then psvmbM to an intense almost nuclear light. The right eye does not resolve or barely makes it resolvable; the left resolves it completely into stars 17..20m. A superb object on a rich ground of milky way."
Journal BAA, 36(3), Dec, p91
about 2.5' diam., brighter part.
"globular cluster, extremely condensed."
Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.
The RNGC (Sulentic and Tifft 1973) notes that this is a 8.5 mag globular cluster.
RA 17 36 17.0 (2000) Dec -44 44 06 Integrated V magnitude 6.72 Central surface brightness, V magnitudes per square arcsecond 14.55 Integrated spectral type G2 Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 1.70 Core radius in arcmin .12. ["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) ]
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
Steve Coe, observing with a 17.5" f/4.5 at 100X, notes: "Bright, pretty large much brighter in the middle, 6 stars resolved at 165X. This globular was seen in the finderscope.
Last night I had a good look at NGC6388 with the 15.5" reflector. There was dew early in the night, but a light breeze later improved the situation so I could have a look to see if I could resolve it.
NGC6388 is a small bright globular cluster. At first it appears very granular in a 32mm eyepiece. There is a definite nucleus becoming suddenly a lot brighter giving the nucleus a crisp sharp edge. The nucleus covers half of the 5' wide cluster.
No star colours were visible in the cluster, and oddly the stars in the fringes were all the same brightness, but in the nucleus there were a few stars brighter than the others in the nucleus (they are most probably not members).
I got glimpses of stars resolved almost all the way to the center. The stars in the nucleus were more easy to see than in the much dimmer fringes, which usually appeared no more than a haze. They were both seen readily in the 17mm.
The cluster has an overall round shape, fading into the background, except on the eastern edge where a dark nebula cuts off a small strip of the fringe. Because of this the nucleus does not appear to lie in the middle of the cluster, but just a bit off to the east.
The nebula was visible in both the 17 & 32mm. It is quite easy to spot the dark nebula as it has a bright 9,5 mag star on its eastern edge (7' away from the center of the cluster). The nebula lies in a N-S elongation with an elongation of just over 2:1. It has a sharp boundary on the cluster side and on its other boundaries are clearly dimmer than the background sky glow outside them. It is cigar shaped except for a small bud going NE. More dark patches with star chains are visible north, outside of the cluster within 15' of its center.
The nucleus of the cluster appears to be in a small equilateral triangle shape, with base running N-S. It has a very sharp SW edge and its N point is a bit fainter than the rest. The 17mm clearly shows a collection of close brightish stars around the apex: a equal brightness pair S of the apex, lying E-W of each other; a single star of similar brightness lies N of the apex and he has a fainter companion lying E of him; another star lies E of the apex.
With enough imagination the fainter background combine with these five making an arced chain almost like a neclace. The triangle nucleus is well positioned to look like the amulet on the neclace. Overall the nucleic area, at least, stands out well from the dim, but star studded background. 20' SW of the cluster lies a bright pale yellow 8th mag star.
I clearly saw more this time than during the weekend when the mirrors and eyepieces were getting wet. That time I did not even resolve stars.
So it may be just the conditions that did not allow Constant to see enough stars resolved or maybe the eyepieces need cleaning. Clear, Dark, Dry Skies
ASSA DSOS: Ed Finlay, observing with a Meade 4-inch ED APO refractor from Johannesburg, 1992 May 30, notes "small, about 3', mag about 7. Quite easy to see. Whitish patch with bright centre. Best at 102x."
"Bright, clearly seen in a wide field ocular. Not resolved into stars." Gabriel Giust, 1994 April 10, 8-inch f/6.7 reflector, 9.7mm Super Plossl, San Isidro, Buenos Aires.
This globular cluster just shows in 11x80's, lying near a pretty large equilateral triangle of stars. About as bright as these stars, it clearly has an extended surface.
24/09/93: 11x80 binoculars, strong moonlight: Midway between Theta Sco and Sigma Ara within a very busy field lies this small, distinct globular, not washed out by the strong moon. It has two 'atennae' stars, so the south-east and north-east.
1998-04-23/24, 11x80 tripod-mounted binoculars, Die Boord. Seeing good, transparency below average, dew. "Like a dewed-up 8th magnitude star, one of a number of 7th-8th mag stars around. The cluster is B, 5' across, R, like a typical globular in binoculars. Has almost no fringe and an even brightness distribution; just like a fuzzy planet. Easy to see."
Location: Campsite (South 23 16 East 29 26).
Sky conditions: Clear, steadiness good.
Instrument: Meade 8 inch, Super wide-angle, 18mm eyepiece; 36.2' fov
DSO Report N
Very bright, large round globular cluster, with a sudden compressed bright core. Well-resolved clear stars up to the fringes. A bright star taking side out to the north and another one to the south in the starfield. Excellent object in a beautiful starfield. A little smaller than NGC 6362.
16-inch f/10 SCT (EP: 2-inch 32mm SW 127x 32' fov; 2-inch 14mm UW 290x 17' fov; 2-inch 8.8mm UW 462x 11' fov)
Very bright, frosty-like round globular cluster, with a core that suddenly broadens. Careful attention reveals splinters of stars on the outer edge. Through the 16" S/C and 127x magnification an 8th magnitude star appears on the south side whilst a 9th magnitude one can be located towards the north. Excellent object nestle in a beautiful star-field. Oblong ring of stars can be seen to the southwest.
Observing site: Pinnacles overlook
[17h 36m 18s, -44° 44' 0"] Bright, but barely granulated.
Telescope: 12" Dobsonian – f4,9. Eyepiece 15mm. FOV- 36'
Sky conditions: Seeing 3/5 (gibbous Moon)
Actual dimensions: 8.7' x 8.7(Cartes Du Ciel)
Globular cluster in Scorpius
Bright fuzzy ball. Dense nucleus. Looks like a bright torch in the mist.
A triangle of stars surround the cluster, two of very bright to the W and NE. One dimmer to the SE.
To the NE triangles of stars, dainty doubles and a few bachelor’s waltz in a circle.
Location:Night Sky Caravan Park,Bonnievale.
Sky Conditions:Whole Milky Way is visible.The sky is clean.
Atmosphere stable with little interference.
In this globular cluster the stars are well resolved and that there are plenty of star chains towards the outskirts of this cluster.This globular cluster has a comparitively round shape which looks like a medium sized soft snowball.In this cluster there is a lot of condensation because the stars are neatly concentrated towards each other.This globular cluster measures 5.6'*5.6'Chart:No.348,NSOG Vol.2.
The Messier objects
The Bennett objects
The Caldwell list
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