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RA: 01h 46m 18s
Dec: +61° 12′ 54″
Ch: MSA:47, U2:16, SA:1
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003), Skiff20080430-s
Type: open cluster, 23r
Mag: B=7.78, V=7.1
Synonyms: H VI-031
Discovered in 1787 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a beautiful cluster of pretty large stars near 15' diameter, considerably rich."
In the 5th edition of Webb's Celestial Objects for Common Telescopes it is described as "visible in finder; field very good at 64x; 80x showed Smyth's little pair, Struve 153 : 8.5, 9.7 mag; 69.2 degrees, 7.5 arcseconds, but not his ruby, 8th mag."
Phelps and Janes give the outer cluster radius as 4.42arcminutes and list the minimum number of cluster members as 413. They include a plotted image of the cluster. [Phelps, R. L. & Janes, K. A. (1994) "Young Open Clusters as Probes of the Star Formation Process. 1. An atlas of open cluster photometry" Astrophys. J. Suppl. Series, 90:31-82.]
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 7.69.
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
Raab, S. (1922) A research on open clusters. Lund Medd. Astron. Obs. Ser. II, 28, 1.
Based of F-A plates: "very well defined and fairly regular in form. Contains 2 rather dense accumulations of stars, sep byu a thin region (2'-3' wide). Besides, there appear a couple of offshoots with fairly bright stars."
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.
Journal BAA, 35, p159
open cluster with two aggregations of stars separated bvy an almost vacant space; angular diam. 20'.
Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.
"A Catalogue of Estimated Parallaxes of 112 Nebulae, Open clusters and Star Groups", Vol 36 (4), p 107-115.
"Fairly well defined loose cluster with two centres." He gives the approx. diameter as 15 arcmin.
Trumpler (Lick Obs Bulletin, Vol 14, No. 420) gives the diameter as 14' and the class as 4 2 m.
Photo Index by Jim Lucyk: Deep Sky #8 Fa84 p25, Burnhams V1 p526.
The RNGC (Sulentic and Tifft 1973) notes that this is a 7.5 mag open cluster.
Harrington notes that "in most finderscopes this cluster appears as a faint smudge just southeast of the midpoint between Delta and Epsilon Cassiopeiae. Despite its relatively bright magnitude of 7.1, NGC 663 remains unresolved in small amateur telescopes. Through 8- to 10-inch instruments the brightest stars .. barely begin to shine through the warm glow of fainter cluster members. My 13.1 inch reflector reveals about two dozen 11th and 12th mag points as well as several dozen dimmer ones. Most are asymmetrically dumped into two regions inside the cluster's 16' diameter. Several form close pairs."
Listed by the Herschel Club, described as "a real pretty rich grouping of stars, counted up to 80 stars. Hint of nebulosity with star magnitudes varying. Easily resolvable, scattered and irregular. 6-inch, 48x."
A 6-inch shows this cluster to be a big, fully resolved, elongated lozenge oriented northwest-southeast, with a dark gulf in its middle. It has 80 stars in an area a quarter degree across, and a total magnitude of 7.1. This cluster, along with NGC 581 and possibly NGC 654, is involved with the Cas OB8 association.
WDS: Srn * in triangle W = ADS 1381: 10.7,11.2; 7".1; 38.
Ern * in triangle W = ADS 1384: 9.4,10.9; 9".3; 105.
Ern * in pair N = ADS 1390: 9.7,10.9; 7".6; 69.
7cm - lgr cl thgan M103 but still br w/mod concen of *s @ 30x. 75x: 70 *s in 15' diam. concen somewhat irreg, and dk lane 2' wide nrly splits cl; this comes in from NW and goes btwn the two wide pairs that are the four brtst cl *s. Nmost of these is a decently close un= pair [ADS 1390]. BS, 25Nov1992, Anderson Mesa.
8cm - lg cl of 15 *s incl wide E-W (Wrn * brtr) pair in N side. outliers all about same mag spread S to oc N659. BS, 17Oct1982, Anderson Mesa.
15cm - avg cl of 30 *s w/cen condens. 15' diam. BS, 25Oct1970, FtL.
- a circlet of five m7-8 *s enclose fntr *s. some haze.
- richest cl so far tonight, biggest, too. 80x shows it 15' diam w/rich fld SW, and dk area starting on NE and extending out that direc. 140x: 100 *s w/mod concen across center, but irreg patchiness, notably an oblong area elong SSE-NNW cutting in from NW into W side of cl. consp pairs with br primaries are: on W (pa110, dm2.5) and NNE (pa75, dm1.0). others fntr, such as nrly = pair not far SW of first mentioned pair. all these res @ 80x. BS, 10Dec1990, Anderson Mesa.
20cm - nice cl of 75 *s in 15' area. well rounded and smoothly condensed at center. * m9+.
25cm - mod lg, br. 20' diam w/60 *s. sev dbls and sl colored *s. mod condensed.
30cm - lg, sl concen, 15' diam. five m9.5 *s w/60 fntr ones. the brtst partic on N. three concens, N lgst.
The Messier objects
The Bennett objects
The Caldwell list
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