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NGC 6522 (14,887 of 18,816)


oc gc pln bn dn gx gxcl ast aka lost




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NGC 6522

NGC 6522, NGC 6551, C 1800-300, Cl VDBH 256, GCl 82, ESO 456-60, ESO 456-43, Bennett 101, I 49, h 3720, GC 4359

RA: 18h 03m 34.08s
Dec: −30° 02′ 2.3″

Con: Sagittarius
Ch: MSA:1415, U2:377, SA:22


(reference key)

Type: globular cluster

Mag: B=10.68, V=9.48

Size: 5.6′
PA: ?


This globular lies about half a degree north-west of Gamma Sagittarii. Just to its east lies the smaller globular NGC 6528.

Historical observations

William Herschel (c.1784)

Synonyms: H I-049

Discovered in 1784 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "B pL bM resolvable."

John Herschel (1847) Cape Observations

Discovered by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "globular, B, R, gvmbM, in a nebuloid portion of the milky way; resolved; stars 16..17m." On a second occassion he called it "globular, pB, S, R, 80 arcseconds, resolved into stars 16m (See the remark on II.200 [NGC 6528]."

NGC/IC Dreyer (1888, 1895, 1908)

It is described in the NGC as bright, pretty large and round, gradually very much brighter toward the middle, well resolved and consisting of stars of 16 mag.

Published comments

Morgan, W.W

A study by W. W. Morgan of Yerkes Observatory indicates this globular cluster to have a spectral type of F8.

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.

Helwan Obs. Bulletin No 21 (1920)

Doubtful whether these are glboaulr clusters, both, especially NGC 6528, may be spirals.

Helwan Obs. Bulletin No 30 (1924)

B globular cluster, 1.25' diameter.

Sulentic & Tifft (1973)

(Sulentic and Tifft 1973) notes that this is a 10.5 mag globular cluster.

Harris, W.E. (1997)

RA 18 03 34.1 (2000) Dec -30 02 02 Integrated V magnitude 8.27 Central surface brightness, V magnitudes per square arcsecond 16.14 Integrated spectral type F7/8 Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 2.50c: Core radius in arcmin .05. ["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

Walter Scott Houston

Houston writes that this globular is "well worth a look ... it is about 5' in diameter and magnitude 8.6."

Bahr-Vollrath, Gerd (1992)

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."

Hogsten, Scott (IAAC)

Observer: Scott Hogsten; Your skills: Intermediate (some years); Date/time of observation: 08-Jul-1999 5:30 UT; Location of site: West Jefferson, Ohio (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 - GEM; Magnification: 100, 120x, 200x; Filter(s): ; Object(s): NGC 6522; Category: Globular cluster.; Class: 6; Constellation: SGR; Data: mag 8.6 size 5.6; Position: RA 18:03 DEC -30:02

Description: This is a small globular cluster located just above the tip of the spout in Teapot. The cluster is very small, round, pretty bright, with a few of the outlying stars resolvable. The seeing was poor so adding more power above 120x did not aide in resolving individual stars. As a side note NGC 6528 is just to the east of this cluster and easily fits in the same field with NGC 6522.


Tom Lorenzin

Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "10.5M; 2' diameter; round and unresolved; GLOB N6528 (11M; 1' diameter) 10' to ESE; 0.5 degree NW of Gamma SGR- the 3M star at the tip of the spout of SGR's Teapot asterism."

Steve Coe

Coe, observing with a 13" f/5.6, notes: "Pretty bright, pretty large, and much brighter in the middle, round and very grainy at 135X."

Contemporary observations

Gabriel Giust

1994 April 10

"Precedes NGC 6528 in the same wide field. Very bright, visible with low power." Gabriel Giust, 1994 April 10, 8-inch f/6.7 reflector, 9.7mm Super Plossl, San Isidro, Buenos Aires.

Magda Streicher

1997 August 05

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 small globular cluster in size, brighter towards the middle and mottled around the edges. This globular cluster reveals a granular look embedded in haziness. A faint star visible right on the edge.

(no date)

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)

Very small unresolved globular cluster, brighter towards the middle and mottled around the edges. This globular cluster reveals a granular look embedded in haziness. The globular NGC 6528 (smaller) is 16' arc minutes east and share the field of view (76x). NGC 6522 is the brighter one of the two with a very small core in comparison. Only 4 degrees distant to the galactic centre.

Tom Bryant

2008-07-03 00:00:00

Observing site: Pinnacles overlook

Telescope: C-8

[18h 3m 36s, -30 2' 0"] A small, faint cluster, not granulated. In the same field as N 6528, both of which are north of Gamma Sgr.

Richard Ford

2012 September, 14th

Location:Night Sky Caravan Park,Bonnievale.

Sky Conditions:Whole Milky is visible.The sky is clean.

Atmosphere stable with little interference.

The shape of this globular cluster looks like a roundish mottled snowball and that the stars are partially resolved and that this clusters stars are clearly resolved on the outskirts of this cluster.The nucleus of this cluster is tightly concentrated towards each other.The central core grows very bright compared to the stars on the outskirts of this cluster.This globular cluster measures 5.5'*5.5'Chart:No.318,NSOG Vol.2.

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