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RA: 18h 51m 0s
Dec: −06° 16′ 0″
Ch: MSA:1318, U2:295, SA:16
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 12r
Mag: B=6.32, V=5.8
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This rich open cluster in Scutum was discovered by Gottfried Kirch of the Berlin Observatory in 1681, who described it as a "small, obscure spot with a star shining through and rendering it more luminous".
In 1715 it was included by Halley in his short list of "nebulous stars".
The Rev. Derham, notes Burnham, seems to have been the first to resolve it into a cluster, his 1732 description reading: "It is not a nebula but a cluster of stars somewhat like that which is in the Milky Way".
Le Gentil, in July 1749, saw it as a "prodigious cluster of very small stars, forming a large, white cloud; six of the principal stars form a large letter V somewhat similar to the Hyades but with the opening towards the south".
Messier, in May 1764, described it as "a cluster of a great number of small stars which can be seen in a good telescope. In a 3-foot instrument it looks like a comet. The cluster is mingled with a faint light; 8 mag. star in cluster."
In the Philosophical Transactions, 1818, William Herschel wrote: "1799, 10 feet finder. The cluster is visible, and, directed by neighbouring stars, it may be seen by the eye. 1783, 1799, 10 feet telescope. Power 300. With 3 inches of aperture, the small stars are not to be distinguished; with 4 inches I can see them. 1803, 1810, large 10 feet telescope. The cluster is of an irregular form, from 9 to 12' in diameter."
Herschel noted that it was "divided into 5 or 6 groups noted independently in a 5.5-inch. An 8 mag. star is a little within the apex."
In the 5th edition of Webb's Celestial Objects for Common Telescopes it is described as "noble fan-shaped cluster, 'magnifica innumerabilium stellarum coacervatio' (d'Arrest); at the upper edge of the broad luminous cloud which marks the shield of Sobieski. Smyth compares it to a flight of wild ducks. William Herschel, stars 11th mag divided into 5 or 6 groups, noted independently with 5.5-inch. An 8th mag star is a little within its apex; an open 8th mag pair S.f. beyond it. According to William Herschel, just visible to the naked eye. Sometimes placed in Scutum Sobieskii."
D'Arrest called it "A magnificent pile of innumerable stars... Irregular and as if divided into several agglomerations".
Admiral Smyth saw the main group as "resembling a flight of wild ducks".
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 12.5' and the class as 2 2 r.
Burnham calls it "an exceptionally fine cluster... one of the outstanding objects of its type for telescopes of moderate aperture." He notes that "it is one of the richest and most compact clusters. In binoculars or a low-power telescope it at first resembles a globular, but with increasing magnification the stars begin to draw apart, finally revealing M 11 as a rich swarm of glittering star points, somewhat triangular in shape with one brighter star near the centre, but no real central nucleus. Barnard thought the extreme diameter to be about 35' and the "wild duck" group about a third of this; Walter Scott Houston confirms this estimate with a 10-inch reflector and describes the cluster as a "carpet of sparkling suns to the very centre with outliers swarming on all sides. A good 10-inch shows hundreds of glittering star point all over the field of view."
The RNGC (Sulentic and Tifft 1973) notes that this is a 7.0 mag open cluster.
Vorontsov-Velyaminov, B. "Integral magnitudes of south star clusters", Astron. Nach. 228, 325. Comparing the brightness of the cluster with the extrafocal images of stars, he estimates the magnitudes as 6.13
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.
Doig, P. (1926) "A Catalogue of Estimated Parallaxes of 112 Nebulae, Open clusters and Star Groups", Vol 36 (4), p 107-115.
"almost globular cluster of fairly bright stars; contains two long-period variables." He gives the approx. diameter as 10 arcmin.
"! globular cluster, rather open, somewhat irregular"
Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
Walter Scott Houston reports observing it with the 12-inch Porter turret telescope at Stellafane, which has a 200-inch focal length (f/17), and notes that the dark nebula Barnard 112, which is located to its south, seems to run right to the edge of this cluster. He writes: "Visually, M11 is rather triangular in shape, but this feature does not record well on long-exposure photographs. In a low-power finder the group looks somewhat like a comet. However, telescopes with apertures as small as four inches will resolve individual stars right to the centre of the cluster. M11 is particularly impressive in long-focus refractors and reflectors. Indeed, the best view I have had of the cluster recently was with the 12-inch f/17 Porter turret telescope." He notes that under good conditions it can be seen with the naked eye. In 1972 he wrote about this cluster which is "immersed in the famous Scutum starcloud. In a small low-power scope the cluster spreads out at least half a degree, and the stars seem to form an arrow-head, but this resemblance lessens as the aperture is increased. Small telescopes will reveal individual stars only at the edges of M11, but a 12-inch can resolve the glittering centre. Within area 12' in diameter, Wallenquist has found about 600 cluster members brighter than 15th mag."
Harrington notes that this cluster is "among the richest and brightest open clusters in the heavens ... if you look at M11 through a small telescope, only a lone, 8th mag sun will be seen amid a nebulous glow. Larger instruments resolve the glow into an amazing crowd of fainter stars shining between 11th and 14th mag. While M11 may appear symmetrical at first, most observers eventually note a blunt V pattern."
Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "6M; 12' diameter; bright, large, irregular in shape; very, very rich for an cluster; brightest star is 9M; 200-plus 11 thru 14M members; truly a beauty! the "WILD DUCK" cluster; cluster N6704 is 1 degree due N."
John Bortle (Webb Society Quarterly Journal, January 1976) using 10x50 binoculars, estimates the visual magnitude as 5.9.
Observer: Lew Gramer; Your skills: Intermediate; Date and UT of Observation: 1997-07-4/5, 03:00 UT; Location: Savoy, MA, USA (42N, elev 700m); Site classification: rural; Limiting magnitude: 7.1 (zenith); Seeing: 4 of 10 - medium good, intermittent cumulus; Moon up: no; Instrument: Naked eye, 50mm Simmons binoculars; Magnification: 1x, 7x; Filters used: None; Object: M11; Category: Open cluster; Constellation: Sct; Data: mag 5.8 size 14'; RA/DE: 18h51m -06o16m; Description:
Visible to the naked eye in these skies, M11 was easily found in binoculars in its accustomed spot, off the tail of Auilla, at the end of the chain of stars lambda & iota Aql and Eta Sct. Even in binocs in this sky though, M11 was still only visible as a broad, slightly irregular haze, SE of a pretty grouping of 7 stars mags. 7 to 9. Near the S end, the well-known mag. 9 orangeish star was fairly prominent. But only with concentration was even a hint of any other resolution seen. Having a binocular mount would probably help to begin resolving this cluster at 7x.
Steve Coe, observing with a 17.5" f/4.5 at 100X, notes: "(M 11) Very bright, very compressed, large, very rich at 135X. "V" shape seen in finder. Orange star of 9th mag is easy at all powers. This cluster is sliced into several pieces by curving dark lanes. It is unique and has always been a favorite.
Johnson: pair SE V=9.2,9.3; 43".
POSS: line of three *s 14'.5 NNW. m8 *s SE = SAO142702/3 5'.5 from center;
pair NE of these: 10.5,12; ~10"; ~25; this lies 9' due E of cl
center. E-W line of f *s in core ~1'.0 N of br `cen *.'
naked eye - difficult due to br Sct *cloud bkgrnd. BS, 29Apr1992, TSP.
6x30mm finder - vis as hazy patch. HM/BS, 2Jul1970, FtL.
7x35mm - gc-like appearance w/mod-strong concen to *ar center (prob br sup *). br m8 pair on SE are single here. BS, 29Apr1992, TSP.
6cm - a haze in the shape of three-fourths of a pie, cen * shining out. BS, 23Jun1971, FtL.
- res @ 80x w/20 *s and haze. cen * seen along with pair to S. BS, FtL.
7cm - 30x: in br cloud elong NW-SE twd trapezoid of *s incl R Sct. cl gran w/dir vis, part res w/averted vis. m9 cen * prominent in SE side of core. 75x: ~100 *s counted out to radius of m10 pair SE. strong broad concen w/a few irreg dk lanes wandering among *s, partic in W side. BS, 23Jun1996, Mars Hill.
15cm - the best cl in sky; extremely rich. on S edge is m7 pair about 40" apart. twd center is m7 * outshining all others. mottled w/dk lanes on on N & W sides showing no *s, resulting in out-of-round appearance. 180x: 150 *s m9+ with some threshold haze in 10' diam. mesmerizing. HM/BS, 2Jul1970, FtL.
- neat view @ 101, well res. HM/BS, 23Jun1971, FtL.
- beautiful object @ 80x, fully res. outliers reach N to line of three m10-11 *s @ 15' radius, which is also nr the border of the lg dk cloud N. concen of *s over bkgrnd evident to same radius in all other direcs except pa~165-180, where another dk cloud is vis (Barnard 112) that is elong N-S and seems to intrude on fringes of cl. main body of cl reaches irreg to radius of two m8 *s SE. m8 * nr center is SE of center. a sm dk patch lies NE of wide pair SE, patch 5' across. on E side of this (beyond its border) is pair: 10.5,12; 10"; 15. inner well-def region is 5 across, about 200 *s here @ 165x (one quadrant counted). total w/in 30' diam ~500 *s. this core has irreg, almost polygonal outline, and big embayment with rel few *s opening W. about 1'.5 N of br cen * is line of three m11-12 *s aligned E-W co-aligned w/a sim-br pair: these form a little `dash' nr E edge of squarish core. sev sm well-def dk clouds are vis S&E...have to do these another time. BS, 9Jun1988, Anderson Mesa.
20cm - vcompact @ 62x. astounding @ 250x. *s seem bunched in segments surrounding cen *. an awe-inspiring sight---makes one wonder. BS, 19May1971, FtL.
- impressively rich. stars and stars and stars. BS, 23Jun1971, FtL.
- gorgeous mass. 62x: a *ry spot w/shining cen *. `flock of wild ducks' effect can be visualized here. 250x: * are grouped in disorganized segments something like a nest of insect larvae. dark lanes abound, winding btwn the grps.
30cm - core 15' across. two dk spots on NW and center w/dk lane btwn. egg of *s, elong N-S. like tapioca pudding. CBL, Roof.
Observing from Stellenbosch, 1983, I used a 2-inch refractor at 30x and wrote: "Severe averted vision -- stars seem to sparkle out. At 48x, the general impression is that of a subtly mottled cluster with 1 bright star near."
A 15.5-inch reflector shows this loose, well spread out cluster to have a bright star lying slightly off-centre. This star, and the pair of bright stars to the southeast of the cluster, are shown on the Uranometria 2000.0 charts. The stars in the central region of the cluster form a distinct rectangle, and this rectangle itself contains a brighter, well-defined square. This square contains smaller groupings of stars, which brings more structure into the image, which lead to an earlier perception of a swastika. However, the gestalt is that of a square.
1995-06-01: 11x80. Kelsey Farm. 23:00 SAST. A brilliant knot of stars. Very much like a globualr cluster. Has a small stellar companion. There is a bright distorted parallelogram just to the north-west, useful in finding the cluster. The star nearest M11 is pale orange.
1997 July 6, Sunday, 21:00 - 23:00 Jonkershoek. 11x80's tripod-mounted. Impressive bright fuzzy object. Massively bright cluster, like a globular cluster, but with a pin-point sharp nucleus, offset to the south-west. A small double star lies further south-west; U2000 shows it inside the cluster.
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
Rich, Large, bright fine open cluster. Bright stars running out in extended trails with dark patches in between. Very busy starfield. About 15 arc minutes in size. The wild duck cluster resembles its name beautifully, with two bright leaders follow the flock in flight.
12-inch f/10 SCT
Rich, large, bright fine open cluster of multitude magnitude stars mingles well with a very busy star field. Bright stars running out in extended trails with dark patches and several lanes in between. Towards the centre a relatively yellow 9th magnitude star overwhelms the cluster. There is a starless patch just off-centre in the western part. A short string of stars circling out to the west, is visible amongst the stars. This wild duck cluster resembles it name well, with two bright 9th magnitude leaders that follow the flock in flight. It might also be described as a tri-angular swarm with the top point to the north. This cluster was discovered by Gottfried Kirsch of the Berlin Observatory in 1681.
Sky Conditions:The fainter parts of the Milky Way are barely visible.Haziness only visible on the horizon.Atmosphere stable with little interference.
This open cluster has the shape of wild ducks swimming in a starry lake of 11th to 12th magnitude stars.M11 is a fairly large open compact cluster which consists of 11th to 13th magnitude stars which is well detached and I have counted 180 stars in this cluster within a fixed diameter.In this cluster the stars are concentrated towards each other while around this cluster there are some starless patches being seen.This open cluster measures 7.3'x 5.2'.Chart No.358,NSOG Vol.2.
Instrument:12-inch Dobsonian Reflector Telescope.
Sky Conditions:The fainter parts of the Milky Way are barely visible.
Transparency of the Sky:Haziness only visible on the horizon.
Seeing:Atmosphere stable with little interference.
Object Type:Open Cluster.
First Impression:This object looks like an open cluster.
Chart Number:No.12(Extract taken out of "Atlas of the Night Sky").
Size:26mm Eyepiece:Field Of View:57'/7=8.1'.
20mm Eyepiece:Field Of View:50'/6=8.3'.
Size in Arc Minutes:8.2'.
Open Cluster is 8.2'*2.7'.
Brightness Profile:Right from the central outskirts of this open cluster it grows equally bright all over.
Challenge Rating:Breathtaking Sight.
This open cluster is well detached and the shape of this cluster looks like a tight swarm of wild ducks.I have found a bright O star which powers this cluster in the centre.I have counted 42 stars in this cluster within a fixed diameter.In overall most of the stars is nearly the same brightness as each other.The stars in this open cluster is strongly concentrated towards each other.On a final note I have found some starless patches around the outskirts of this cluster.
The Messier objects
The Bennett objects
The Caldwell list
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