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NGC 7089 (16,784 of 18,816)

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Messier 2

NGC 7089, C 2130-010, GCl 121, HD 205146, Bennett 127, Messier 2, h 2125, GC 4678

RA: 21h 33m 27s
Dec: −00° 49′ 24″

Con: Aquarius
Ch: MSA:1286, U2:255, SA:17

Ref: SIMBAD, SEDS

(reference key)

Type: globular cluster

Mag: B=?, V=6.3

Size: 16′
PA: ?

Image gallery

Photos  (1)

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History and Accurate Positions for the NGC/IC Objects (Corwin 2004)

NGC 7089. Shawl and White's position, though correctly copied from their 1986 list, is apparently 2 seconds of time too large. The cluster's image on both POSS1 and POSS2, though burned out in the center, is elongated and symmetric about a position 33 arcsec west of the Shawl/White position. I suspect a typo in their table.

Also see NGC 7088.

Historical observations

Maraldi

A fine bright globular, discovered in 1746 by Maraldi.

Messier, Charles

Catalogued in 1760 by Charles Messier.

NGC/IC Dreyer (1888, 1895, 1908)

The NGC records it as "very remarkable, bright, very large, gradually pretty much brighter to the middle, well resolved into stars, stars extremely small."

William Herschel (c.1784)

In the Philosophical Transactions, 1814, William Herschel wrote "September 4, 1799. 40 feet telescope, power 240; I examined the 2nd of the Connoissance des Temps. It appeared very brilliant and luminous. The scattered stars were brought to a good, well determined focus, from which it appears that the central condensed light is owing to a multitude of stars that appeared at various distances behind and near each other. I could actually see and distinguish the stars even in the central mass. The Rev. Mr. Vince, Plumian Professor of Astronomy at Cambridge, saw it in the same telescope as described."

In the Philosophical Transactions, 1818, William Herschel wrote: "1799, 7 feet finder of the telescope. It is visible as a star. 1810, it may just be perceived to have rather a larger diameter than a star. 1783, 2 feet sweeper. It is like a telescopic comet. 1794, 7 feet telescope. With 287 power I can see that it is a cluster of stars, many of them being visible. 1810, 10 feet telescope. A beautiful bright object. 1784, 1785, 1802, 20 feet telescope. A cluster of very compressed exceedingly small stars. 1805, 1810, large 10 feet telescope. Its diameter with 108 power is 4' 59 seconds; with 171 and 220 power it is 6'. 1799, 40 feet telescope. A globular cluster of stars."

Webb, T.W. (1893)

In the 5th edition of Webb's Celestial Objects for Common Telescopes it is described as "beautiful round nebula, diam. 5' or 6', showing with 3.7-inch a granulated aspect, the precursor of resolution. With 9-inch speculum, resolution evident the margin seems to diffuse itself away, probably in rays. John Herschel compares it to a heap of fine sand, and considers it to be composed of thousands of 15th mag stars. Smyth observes that 'this magnificent ball of stars condenses to the centre and presents so fine a spherical form, that imagination cannot but picture the inconceivable brilliance of their visible heavens to its animated myriads.' "

Published comments

Burnham's Celestial Handbook

Burnham notes that the visual diameter of about 7' is increased to about 11' on the best photographs. The total integrated magnitude is about 6.0 In large telescopes, Burnham calls the cluster a "wonderful sight", and he notes that John Herschel compared the distribution of stars to a heap of fine sand.

Doig, P. (1925)

Doig, P. (1925) Notes on the nebulae and clusters in Webb's 'Celestial Objects for Common Telescopes' (Sixth edition, Vol.ii). Part I. M.N.R.A.S., 35(5), 159.

Bailey, S.I. (1908)

"! globular cluster, condensed"

Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.

Remarks, p.218: "this globular cluster contains 10 known variable stars."

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a 7.5 mag globular cluster.

Harris, W.E. (1997)

RA 21 33 29.3 (2000) Dec -00 49 23 Integrated V magnitude 6.47 Central surface brightness, V magnitudes per square arcsecond 15.92 Integrated spectral type F4 Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 1.80 Core radius in arcmin .34. ["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) ]

Melotte, P.J. (1915)

A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.

Modern observations

Hartung, E.J. (1968) Astron.Obj.South.Tel

Hartung notes that "this very fine object is a mass of innumerable stars concentrated towards the centre and dispersing outwards into irregular wispy rays of outliers 5' across. Resolution is just evident with 15cm and with 10.5cm the cluster is conspicuous and granular, with outlier haze."

Walter Scott Houston

Houston says this cluster is an easy target even for small telescopes. Its stars shine with the combined light of a single 6th mag star, putting the cluster on the verge of naked eye visibility under clear, dark skies. Leslie Peltier reported that M2 was only a trifle more difficult for the naked eye that the spiral M33. Steve Coe notes that it has "lovely chains of stars meandering outward from the core, and several dark lanes are visible."

Tom Lorenzin

Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "6M; 7' diameter; bright and round; just resolved at 100x; 13M and dimmer members; 11M star 2' due N of core; 10M star 5' NNW of core."

Sanford (1989) Observing the Constellations

Sanford calls it "one of the better globulars in the sky", noting that it "becomes a ball of faint and very evenly bright stars of 13th magnitude and fainter in a 10-inch."

Harrington, Phil (1990)

Phil Harrington (1990, Touring the Universe through Binoculars) calls it "the brightest nonstellar object in Aquarius .. visible through nearly all binoculars as a not-quite-stellar 'star' . . large glasses will show that M2 is not perfectly round, but instead has a slightly oval disk."

Harrington, Phil (1986)

Harrington, P. (1986) An observer's guide to globular clusters. Sky&Telescope, Aug, 198.

a 4inch will show some of its stars but a 12inch is needed for complete resolution. .. it does not appear perfectly round.

Steve Coe

Steve Coe, using a 17.5" f/4.5, notes: "(M 2) this is the showpiece of the constellation. It is bright, very large and very bright in the middle at 100X. This globular is easy in the 10X50 finderscope. At 250X in the 17.5" f/4.5 there are 12 stars resolved in the central core region and a profusion of stars in the outer corona. All these stars are superimposed on an unresolved backround haze of stars. Lovely chains of stars meander outward from the bright core and several dark lanes are visible through the cluster. In the 13" from Cherry Rd. on a 8/10 nite I counted 41 stars at 220X. There are two dark areas on the SE side. The entire globular has a lot of backround sparkling stars. 13" Sentinel 9/10 just glimpsed naked eye, 20% of the time. 100X !!, bright, very large, very much brighter in the middle, many very faint stars, averted vision makes it explode with faint starpoints. 40 stars counted, with three levels of brightening, but it need higher power to really resolve this globe of stars. It looks like a globular, even in the 11X80 finder. 220X 200 stars estimated by counting 50 in NW quadrant, many lovely chains wind out from core. There is a star of about 8th mag on the north side. A thin dark lane is at the eastern edge of the core, where the compressed core meets the outer chains of stars. 440X not quite resolved to the core, dark marking more prominent, a great view on a steady night."

Bortle, John (1976)

John Bortle (Webb Society Quarterly Journal, January 1976) using 10x50 binoculars, estimates the visual magnitude as 6.5.

Gramer, Lew (IAAC)

Observer: Lew Gramer Your skills: Intermediate Date and UT of Observation: 1997-07-10/11, 04:05 UT Location: Medford, MA, USA (42N) Site classification: urban Limiting magnitude: 5.5 (zenith), 4.9 (in S) Seeing: 5 of 10 - mediocre Moon up: no Instrument: 50mm Simmons binoculars Magnification: 7x Filters used: None Object: M2 Category: Globular cluster Constellation: Aqr Data: mag 6.5 size 13' RA/DE: 21h34m -00o50m

Description: "An easy sweep about 1.5 binocular fields (6o) SW of the "Y" or Water Jar in Aqr, past the bright star alpha Aqr (Sadalmelik). M2 could be seen as a subtle, loose grey spot in an otherwise near-empty field. A pretty pair of white mag 7 stars about 1o NNE of M2, separated by about 30', point almost directly at it."

Observer: Lew Gramer Your skills: Intermediate Date and UT of Observation: 1997-07-5/6, 07:15 UT Location: Savoy, MA, USA (42N, elev 700m) Site classification: rural Limiting magnitude: 6.9 to 6.0 (in growing twilight) Seeing: 4 of 10 - medium good Moon up: no Instrument: 20" f/5 Tectron truss-tube dob Newtonian reflector Magnification: 210x, 420x, 630x Filters used: None Object: M 2 Category: Globular cluster [II] Constellation: Aqr Data: mag 6.6 size 12.9' RA/DE: 21h33m -00o49m

Description: "By far the best thing to look at during growing twilight (aside from the brighter planets) are GLOBULAR CLUSTERS! The Messiers and bright NGCs are especially satisfying, as a brightening sky provides a fascinating kaleidoscope of changing contrast effects. On this morning, I noted that the bright core of M2 was showing three strikingly BRIGHT "lobes" or pseudopods of unresolved haze at 210x. These lobes pointed NE, SSW, and E, each being about 2' long and all of them being arrayed in a pretty trefoil around the brightest center of the cluster. Switching epcs to 420x - racing against time - these 3 lobes appeared yet MORE prominent (despite the fact that the cluster was more completely resolved), while a mag. 12 star was noted directly opposite to and offsetting the E lobe. The outer, still-unresolved halo of the globular actually appeared "eagle-shaped" (or maybe "bomber-jet" shaped!), showing a distinct dark area W of the core; while the core extended to the E, tapering from 4' wide at center out to a much fainter 1' wide halo, before ending abruptly in dark field after 6'; while the halo spewed out LONG wing-shaped outliers extending 8' both to N & S symmetrically, with well-resolved stars then straggling outward to finally merge with the background field. At 630x, now well into twilight, many stars resolved throughout the cluster - even sparkling in dizzying swarms over the still hazy innermost core, which was now an unresolved irregular blob, less than 2' wide, brightening rapidly to a stunning, stellar nucleus. As the terrestial objects around me began to assume distinct shapes, I breathed a sigh, and then began writing my log furiously, trying to get this all down before swinging on to some planets. FUN!! :)"

Brian Skiff

ApJ Suppl 29:397 and AJ 93:856: V(tip)=13.1. br * NE @ 4'.43 radius,

V=10.2. thus 1988 15cm obs total diam ~9', main body ~5', core ~1'.25.

6cm - 5' diam. evenly-well [strong even?] concen w/o nuc. CBL, Slate Mtn.

- smooth, well concen. * 5' NE.

7cm - about as br as M15 @ 30x and nrly as hisfcbr, but not so sharply concen: strong-even rather than strong-sharp as w/M15. also easier to res: def grainy @ 50x, where halo reaches 2/3 way to m10 * NE. 110x shows a couple doz *s; concen pretty smooth and w/o zones. BS, 21Nov1992, Anderson Mesa.

- still looks better res than M15. smlr than M15, reaching 2/3 way to m10 * NE. BS, 25Nov1992, Anderson Mesa.

8cm - maybe a bit lgr than M15, but sl fntr and less concen. BS, 15Sep1982, Anderson Mesa.

15cm - seems brtr than M15. vbr, intense core and little surrounding haze. BS, 19May1971, FtL.

- almost *-like nuc. br inwards and fntr haze surrounding it. diam 7' w/no res. HM?

- vsharply concen haze @ 30x. res from 80x up. 165x/140x (latter preferred): seems sl elong ~SSE-NNW, still hazy but ~100 *s res. outliers extend NE to m9.5 * at 5' radius, perhaps sl beyond this radius to SSE & NNW ---> call it 12'x10'. concen mod sharp. main body sl lgr than distance to * NE, core one-fourth of this. not as well res as M15. BS, 8Sep1988, Anderson Mesa.

- sl smlr & a bit less well concen than M15, just obs'd @ 80x. 195x: reaches as far as m12 pair on SE side, and nrly to m9 * NE. strong even concen. part res @ 80x, 195x shows lots of *s w/strong unres haziness. wk Moonlight. BS, 17Nov1993, LCO.

20cm - distinct core w/fntr surrounding haze. even light and no res. FtL.

- part res @ 250x, core more dense than in M15. BS, 23Jun1971, FtL.

25cm - looks sim to M15 @ 45x. 179x shows a well-res oval mass w/broad center. 8'x6' w/extns to 12'. BS, 22Aug1971, FtL.

30cm - nice, br. good res w/haze to 4'.5. smoothly, well [strong even?] concen, smoothness due to even mags of *s: no prominent br ones. 7' overall in N-S oval, mostly expressed in halo. CBL, Roof.

Gross, Todd (IAAC)

Observer: Todd Gross Your skill: Intermediate Date and UT of observation: 08/02/97 0600 GMT Location & latitude: 22 miles west of Boston, Ma. 42.3N Site classification: Suburban Limiting magnitude (visual): 4.9 (estimated) 4.0(est) in vicinity of object Seeing (1 to 10 - worst-best): 5 Moon up (phase?): No Instrument: 16" Dob, 96%, 99% coatings Magnifications: 94x, and 233x w. Televue Binoviewer Filters used: Object: M2

Description: "Did not spend enough time with this fabulous object. It was moving closer to the horizon and into the trees and light pollution. However, even in light pollution, substantially resolved to pretty pinpoints at 94x, and quite substantially resolved at 233x. Very pretty red foreground star offset about 1/2 out from center. Globular is quite classic looking and symetrical. Highly resolved except for a broad, round, dense lumpy core."

Contemporary observations

Auke Slotegraaf

2016 October 30, Sunday

Location: Night Sky Caravan Farm, Bonnievale.

Date: 2016 Oct 30, Sunday.

Time: 23:16 SAST

Telescope: Little Martin (4-inch f/6.5 Celestron refractor)

11-mm Nagler Type6 (60x): Bright, pretty large globular cluster with a broad, bright centre and a very dim, large halo.

11-mm Nagler+ Powermate (150x): Mottled with averted vision.

1997 November 29

1997 November 29/30, Sat/Sun: Jonkershoek, seeing 3, transparency 3, sky darkness 4, lim.mag. at south pole 6.0 (naked eye), 10.7 (binoculars at pole) Strong SE wind. "a very bright, small globular cluster; looks like a bright star seen through mist. The brightest part is about 1 arcmin across. Very easy object, but not immediately obvious as a non-stellar object."

Magda Streicher

(no date)

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

Large, roundish, faint granular appearance with stars partly resolved. Much brighter to the middle, hazy fringes, and a star to the north east edge accompany with bright stars in the field. Fine object, about 10 arc minutes in size.

2007 Jul 14

Alldays

12-inch f/10 SCT (76x, 95x)

Good example of a nice halo of faint stars around a very dense core. Three 11-magnitude stars situated on the eastern side help to pin-point data around the globular. A very faint double star can be seen in the northern fringes of the globular, although I could not spit it.

(no date)

Alldays (22.50S, 20.12E, 770m).

16-inch f/10 SCT (EP: 2-inch 32mm SW 127x 32' fov; 2-inch 14mm UW 290x 17' fov)

Large, round swarm of flickering lights in thousands, working up to a broad soft core. It shows a soft hazy outer envelope. It is a magnificent view (290x) with star splinters across the whole surface and short star strings that differ in brightness, which extend into the field of view. Dark lines can be discerned with careful observation. In the northeast periphery, a 10th magnitude star is seen towards the very busy star-field. Reflects a fine lovely object. Evident the margin seems to diffuse itself away, probably in rays. Discovered by Maraldi in 1746. All been said, the outliers is very nice and span almost 6' outwards. The 11Mag star is to the north, and a 10 Magnitude star slightly further to the NW.

Richard Ford

2016, July, 2nd

Location:Perdeberg.

Time:11:15pm.

Sky Conditions:The fainter parts of the Milky Way are barely visible.Haziness only visible on the horizon.Atmosphere stable with little interference.

Instrument:12-inch Dobsonian.

In this globular cluster the stars are very well resolved and that this cluster is moderately large and condensed.The stars in this cluster is strongly concentrated towards each other and that the galactic nucleus is very condensed in this cluster.This globular cluster measures 4'x 3'.Chart No:32,NSOG Vol.1.

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