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RA: 17h 48m 52.67s
Dec: −20° 21′ 34.5″
Ch: MSA:1369, U2:338, SA:22
Ref: SIMBAD, SEDS
Type: globular cluster
Mag: B=12.01, V=10.1
Synonyms: H I-150
Discovered in 1786 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "cB, R, vgmbM, about 1.5' diameter."
1.5.x1.5', pB globular cluster, central portion not resolved, some indication of the stars being in spiral formation.
RA 17 48 52.6 (2000) Dec -20 21 34 Integrated V magnitude 9.20 Central surface brightness, V magnitudes per square arcsecond 17.02 Integrated spectral type G4 Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 1.70 Core radius in arcmin .13. ["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) ]
The RNGC (Sulentic and Tifft 1973) notes that this is a 12.0 mag globular cluster.
A study by W. W. Morgan of Yerkes Observatory indicates this globular cluster to have a spectral type of G5.
Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "10M; 1' diameter; bright, small and round with little center brightness; unresolved; planetary N6445 20' N and a little E."
Coe, observing with a 13" f/5.6, notes: "Pretty bright, pretty small, compressed and much brighter in the middle at 135X. Raising the power to 220X brings out ragged edges with 10 stars resolved."
Donald J. Ware:"This is a small, highly concentrated globular cluster with an almost stellar core. I was not able to resolve it in my telescope, but it makes a fine low power eyepiece pair with the next object."
Location: Pietersburg South 23 53. East 29 28.
Sky conditions: Fair.
Instrument: Meade 12 inch.( Eyepiece super 40mm).
Date: 1997 August 05
Field of view: 52.7 minutes.
Very very small, roundish and faint globular cluster, gradually brighter towards the middle. Fringy-like with no structure in very hazy and nebulous surroundings.
12-inch f/10 SCT (EP: 2-inch 32mm SW 95x 42' fov; 2-inch 14mm UW 218x 23' fov; 2-inch 8.8mm UW 346x 15' fov)
Rather small ball of cotton wool that slowly brightens towards the centre that gives the globular cluster the appearance of it being moulded together. No structure and very hazy out of focus feeling. With (346x) it appears mottled although no stars resolved. Discovered by William Herschel with an 18.7-speculum telescope.
Observing site: Pinnacles overlook
[17h 48m 54s, -20° 22' 0"] A small, faint cluster, not granulated.
Location:Night Sky Caravan Park,Bonnievale.
Sky Conditions:Whole Milky Way is visible.The sky is clean.
Atmosphere stable with little interference.
This globular cluster looks like a very small round halo of faint light and that the appearance of this cluster looks like a snowball.No resolution of stars in this cluster is seen and that the core of this cluster cluster is very condensed.The nucleus of this cluster grows slightly brighter compared to the far outskirts of this globular cluster.This globular cluster measures 2.5'*2.5'Chart:No.315,NSOG Vol.2.
The Messier objects
The Bennett objects
The Caldwell list
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