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RA: 18h 04m 49.61s
Dec: −30° 03′ 20.8″
Ch: MSA:1415, U2:377, SA:22
Ref: SIMBAD, SEDS
Type: globular cluster
Mag: B=12.12, V=10.65
Synonyms: H II-200
Discovered in 1784 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "F, pS, r, unequally bright." This globular lies about half a degree north-west of Gamma Sagittarii. It is described in the NGC as pretty faint, considerably small and round, gradually brighter to the middle, well resolved and consisting of stars of 16 mag. Just to its west lies the brighter globular NGC 6522.
Discovered by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "globular, pB, R, gbM, resolved into stars 16..17m, in a nebuloid of the milky way." On a second occassion he called it "globular, B, S, R, glbM, resolved into stars 16m. Both this and I.49 occur on a ground so astronishingly rich and stippled with stars 17m individually discernible, as hardly to admit a pin's point between the stars, and this fills more than the whole field or many fields."
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.
Doubtful whether these are glboaulr clusters, both, especially NGC 6528, may be spirals.
pF globular cluster, 0.75' diameter, both in a very rich field with lanes of absorption.
The RNGC (Sulentic and Tifft 1973) notes that this is a 11.0 mag globular cluster.
RA 18 04 49.6 (2000) Dec -30 03 21 Integrated V magnitude 9.60 Central surface brightness, V magnitudes per square arcsecond 16.91 Integrated spectral type G3 Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 2.29 Core radius in arcmin .09. ["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) ]
Houston notes that this globular "is well worth a look..."
Gerd Bahr-Vollrath (Noosa Heads, Queensland, Australia) observing with an 8-inch f/12 SCT, writes in the The Webb Society Nebulae and Clusters Section Report No. 10, July 1992: " [NGC 6522 & NGC 6528] Separated by less than 20', these two globular clusters can be viewed together in a medium power field of view. A rare 'double'! NGC 6522 is the brighter and larger of the pair and shows a gradual increase in brightness towards a prominent small core. NGC 6528 is a small round glow with only a slight increase in brightness towards the core. Both globulars were unresolved and are set in a very rich starfield, only four degrees from the galactic centre."
Observer: Scott Hogsten; Your skills: Intermediate (some years); Date/time of observation: 8-Jul-1999 5:30 UT; Location of site: West Jefferson, OH (Lat 40, Elev ); Site classification: Rural; Sky darkness: 5.5 Limiting magnitude; Seeing: 5 1-10 Seeing Scale (10 best); Moon presence: None - moon not in sky; Instrument: C-14 - F11 - GEM; Magnification: 100x, 120x, 200x; Filter(s): ; Object(s): NGC 6528; Category: Globular cluster.; Class: 5; Constellation: SGR; Data: mag 9.5 size 3.7'; Position: RA 18:05 DEC -30:03; Description:
This is a small dim globular cluster located just above the tip of the spout in Teapot. The cluster is very small, faint, and appeared to be slightly oval in shape. Adding power did not resolve any individual stars in the cluster but did reveal a gradual brightening starting just inside the edge of the cluster.
note NGC 6528 is just to the east of NGC 6522 and easily fits in the same field with NGC 6522.
Steve Coe, observing with a 13" f/5.6, notes: "Pretty bright, pretty large, bright in the middle at 100X. It is paired next to NGC 6522, two nearly matched globulars afloat in a rich Milky Way field just at the tip of the spout of the Teapot."
"Follows NGC 6522 in the same wide field. Faint, visible with medium and high power." Gabriel Giust, 1994 April 10, 8-inch f/6.7 reflector, 9.7mm Super Plossl, San Isidro, Buenos Aires.
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.
This small roundish globular cluster is starlike in appearance compressed with haziness around it in a medium to busy starfield. Both NGC 6528 and NGC 6522 are visible in my starfield and make a beautiful pair.
12-inch f/10 SCT (EP: 2-inch 40mm SW 76x 53' fov; 2-inch 14mm UW 218x 23' fov; 2-inch 8.8mm UW 346x 15' fov)
A small roundish globular cluster which looks like an out of focus star but with a very strong bright core. Very much compressed with soft haziness around it. I were looking for Baad's Window (346x) in the surroundings between the nearly twin globular's but it was not be found. Agree with John Herschel on this exceptional busy star-field. John Herschel has this to say about the star field around these globular clusters. "Occur on a ground so astonishingly rich and stippled with stars, individually discernible, as hardly to admit a pin's point between the stars".
Observing site: Pinnacles overlook
[18h 4m 48s, -30° 3' 0"] A small, faint cluster, not granulated. In the same field as N 6522, both of which are north of Gamma Sgr.
Location:Night Sky Caravan Park,Bonnievale.
Sky Conditions:Whole Milky is visible.The sky is clean.
Atmosphere stable with little interference.
This globular cluster has a somewhat granular appearance where some of the stars are resolved on the outskirts of this cluster.The central core of this cluster is very bright compared to the stars on the far outskirts of this globular cluster and that the central core of this cluster is compact and that it looks like a round snowball in space in a bright field of stars.This globular cluster measures 5.5'*5.5'.Chart:No.319,NSOG Vol.2.
The Messier objects
The Bennett objects
The Caldwell list
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