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RA: 23h 57m 24s
Dec: +56° 42′ 30″
Ch: MSA:1083, U2:35, SA:3
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 22r
Mag: B=7.68, V=6.7
Discovered by Caroline Herschel.
Synonyms: H VI-030
Recorded on October 18, 1787 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a beautiful cluster of very compressed small stars, very rich. C.H. [Caroline Hersche] discovered it in 1783."
In the 5th edition of Webb's Celestial Objects for Common Telescopes it is described as "beautiful large faint cloud of minute stars 'A most superb cluster.' 'A mere condensed patch' as Smyth remarks, 'in a vast region of inexpressible splendour, spreading over many field;' including the whole Galaxy through this and the adjacent constellations. A beautiful group in a rich field lies about 3/4 degrees following Delta Cas. Glorious region between Pi and Omicron Cas."
Raab, S. (1922) A research on open clusters. Lund Medd. Astron. Obs. Ser. II, 28, 1.
Discussed, based of F-A plates.
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.
Burnham calls it an unusually rich cluster. "To the observer with binoculars, it is a hazy patch of unresolvable star dust; in a good 3-inch glass a rich sprinkling of star points begins to appear across its surface, and the view grows steadily more impressive with every increase in the size and quality of the telescope. Sir John Herschel described it as a most superb cluster which fills the field and is full of stars, gradually brighter in the middle but without a nuclear condensation. T. W. Webb refers to it as a 'large faint cloud of minute stars' and Smythe speaks of the surrounding area as a 'vast region of inexpressible splendor'. The whole group covers an area nearly half a degree in diameter, and the stars range from the 11th to the 18th magnitudes ... at least a 1000 stars are probably actual members of this cluster ... the brightest members are orange giants of type K4 III ... "
"cluster, fairly condensed"
Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.
Vorontsov-Velyaminov, B. (1925) "Catalogue of integrated magnitudes of star clusters", Astron. Nach. 226.195. Comparing the brightness of the cluster with the extrafocal images of stars, he estimates the magnitude as 8.13.
Photo Index by Jim Lucyk: Sky&Tel. 11/81 p509, Sky&Tel. 12/79 p601, Astronomy mag. 1/79 p48, Astronomy mag. 5/85 p60, Deep Sky #8 Fa84 p27, Burnhams V1 p532.
The RNGC (Sulentic and Tifft 1973) notes that this is a 9.5 mag open cluster.
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 19' and the class as 3 1 r.
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
Houston calls this cluster "particularly attractive" and about half a degree across. He notes that it can be found easily as a hazy patch between Rho and Sigma Cassiopeiae. Sagot and Texereau in Revue des Constellations notes that a 6-inch shows it as "a splendid swarm of about 200 stars of magnitude 10 to 12." Houston writes: "Lookiung at this cluster, one may gain the impression of a knot of bright stars superimposed on a larger mass of faint points of light."
Harrington notes that the cluster is famous as one of the richest open clusters north of the celestial equator. Current estimates put the total population at 300 suns crammed into a 16' circle. "This great density, coupled with the fact that none of the cluster stars shine brighter than magnitude 10.7, makes NGC 7789 difficult to resolve in small backyard telescopes. A 6-inch instrument reveals about five dozen stars sprinkled across a moderately bright background glow. An 8-inch increases the star count to about 100. Resolution steadily increases as aperture grows, with close to 200 stars visible in 12- to 14-inch instruments. My 13.1 inch Newtonian shows the cluster's few bright stars set in a loose arc. Curiously, I didn't notice the effect when viewing with my 8-inch reflector."
According to Sanford "there are roughly 1,000 members of the group and it's a striking sight in a 10-inch at 70x. There is a wide double on each side of the cluster, adding interest to this field."
Listed by the Herschel Club, described as "a large cluster, circular in shape, stands out well. Hint of nebulosity evident, bright and rich. 8-inch, 48x."
Mullaney calls it a "ghostly open cluster .. glowing softly at about 7th mag and spanning some 30', this cosmic jewel box contains at least 300 suns (some estimates put the count as high as 900), making it among the richest objects of its class. Users of small telescopes often pass over this object at first glance since the individual stars are relatively faint and blend in with the rich Milky Way background. In 6-inch and larger instruments having at least a one degree field of view, it is a fascinating sight. Most of the members of this distant stelllar commune are remarkably uniform in lustre, looking like diamond dust against a black velvet sky."
Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "10M; 20' diameter; extremely rich (many hundreds of 11M and dimmer members), large and condensed! 1 degree to S and a little E is DBL ST Sigma CAS."
Observer:Steve Coe Your skills: Expert Date and UT of Observation: 28 Nov 97 Location: 100 miles SW of Phoenix, AZ Site classification: rural desert Limiting magnitude: 6.7 Seeing: 7/10 very good Moon up: no Instrument: 13" f/5.6 on Bigfoot German EQ. with 11X80 finder Magnification: 60X, 100X, 150X, 220X Filters used: none Object: NGC 7789 Category: OC Constellation: CAS Data: 6.7 mag 16' RA/DE: 23 57.0 +56 44
Description: This magnificent object is obviously a cluster, even in the 11X80 finder. Only 2 stars are resolved but the cluster is bright, large and brighter in the middle. With the 13" at 60X it is rich and much compressed, I can resolve 32 stars even at the lowest power and there are 2 dark lanes winding through the cluster. 100X with a 22mm Panoptic is a great view, I counted 76 stars of mags 10 and fainter. The cluster is about one third of the field of view. There are lots of curved chains of stars within the cluster. Going to 150X with the 14mm Meade UWA provides what I considered to be the best view, the cluster is about half the field and so many stars are resolved that I counted 63 in the NE quadrant alone, so I estimate over 250 member stars at this power. There are many dark lanes now seen within this compressed cluster and the lovely winding chains of stars are very prominent. At this power and at 220X there are 9 faint, delicate binary stars that are seen within the cluster. All the stars are white or very light yellow, little color seen; but wow, what a field full of stars. A long-time favorite.
7x35mm - fairly br circ cloud, broad concen. just barely grainy. brtr * on NW just off edge. BS, 28Jun1992, Hutch Mtn.
6cm - med br glow w/o res.
7cm - beautiful rich cl with many *s res @ 30x. 75x shows about 60 *s w/o much difficulty in well-def main body 12' diam. lots more @ threshold, however, leading to mildly hazy appearance w/inattention. BS, 25Nov1992, Anderson Mesa.
15cm - 20 diam, 60 *s. not much haziness. some brtr *s on the N side.
- excellent vrich cl well res in rich fld @ 50x. outliers to 25' diam, or roughly radius of m9.5-10 * at 12' in pa170 from center (brtr of two *s there). core 10' diam is well def and unconcen. 140x shows 300 *s here (one quad counted). sev f pairs, e.g. m10.5 * nr S edge of core has two comps (wider one on W, other closer on S) and 2' NE of this is roughly= m13.5 pair of 8" sep. more outliers in NE quad, perhaps due to patchy absorption. BS, 26Sep1990, Anderson Mesa.
20cm - lg f cl of about 100 *s of m10+. quite round. averted vis needed for best view. BS, 26Jun1971, FtL.
25cm - fine @ 80x w/about 100 mod br *s in 30' area. BS, 22Aug1971, FtL.
30cm - 149x: nrly fills 22' fld: 20' diam. uneven scattering w/150 *s to m14.
Alldays (22.50S, 20.12E, 770m).
12-inch f/10 SCT (76x, 218x)
NGC 7789, displays a swarm of faint splinter stars, somewhat elongated in a SW to NE direction, and more condensed towards the NW. On the far NE edge of the cluster is a prominent short string that merges with the busy star field. I paused a moment during this late night, feeling relatively warm with my jacket and beanie. I wondered whether Caroline would also have worn three pairs of socks over each another.
The Messier objects
The Bennett objects
The Caldwell list
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