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NGC 7023 (16,524 of 18,816)

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Iris Nebula

NGC 7023, Ced 187, DG 167, LBN 487, LBN 104.08+14.21, VDB 139, Bernes 39, Magakian 846, V380 Cep, Caldwell 4, Iris Nebula, IV 74, GC 4634

RA: 21h 01m 35.5s
Dec: +68° 10′ 11″

Con: Cepheus
Ch: MSA:1061, U2:33, SA:3

Ref: NGC/IC, [2003A&A...399..141M], Archinal&Hynes (2003)

(reference key)

Type: bright nebula

Mag: B=?, V=?

Size: 20′ x 18′
PA: ?

Image gallery

Photos  (4)

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

NGC 7023 is an impressive diffuse nebula in Cygnus, made more so by the obscuring dark cloud surrounding it. It makes a fine sight in a six-inch which will not see deeply enough to pick up what faint stars there are scattered around the nebula -- it appears to stand alone in a large void in the sky.

There is no difficulty with the identification, though I am curious as to why JH did not pick it up. The NGC entry is based on a single observation by his father.

Historical observations

William Herschel (c.1784)

Synonyms: H IV-074

Discovered in 1794 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a star 7m very much affected with nebulosity, which more than fills the field. It seems to extend to at least a degree all around; smaller stars, such as 9 or 10m, of which there are many, are perfectly free from this appearance. A star 7-8m is perfectly free from this appearance."

NGC/IC Dreyer (1888, 1895, 1908)

Noted in the NGC as a star of 7th magnitude in an extremely faint, extremely large nebulosity. Dreyer notes that the star is Fedorenko 3684, and adds that he has seen the nebulosity as particularly distinct north and south of the star.

Published comments

Hardcastle, J.A. (1914)

Hardcastle, J.A. (1914) Nebulae seen on the Franklin-Adams plates. MNRAS, 74(8), 699-707. [commentary in Shapley, H. & Ames, A. (1932) A survey of the external galaxies brighter than the thirteenth magnitude.]

Classified as "probably spiral."

Notes: "Crossley 65."

Cederblad, S. (1946) [VII/231]

Ced 187 (NGC 7023)

Position (1900): RA 21 0.6, Dec + 67 46

Star: +67 1283 (Mp=7.10, V=7.20, SpT=B5se)

Spectrum of nebula: continuous spectrum (observed)

Classification: Neb associated with mainly one star (which may be multiple) - star surrounded by a neb envelope with conspicuous structure (eg. IC 5146)

Size: 18'x18'

Notes: "NGC 7023 = GC 4634 = H IV 74. Disc. 1792. (114, 196, 216, 294, 337, 366, 409 Pl 65, 410, 411, 482, 486, 547, 549, 550, 578, 615 Pl 24, 630 Pl 22, 691, 715, 813, 820, 821). R. +67-1283 = HD 200775 = Boss 29401."

Dorschner & Gürtler (1963)

Untersuchungen uber Reflexionsnebel.

DG 167

= NGC 7023, Ced 187

Pos (1950.0) 21:01.3, +67:58

Size: 20x18 (blue), 13x11 (red).

Lynds, B.T. (1965)

Beverly Lynds (Astrophysical Journal Supplement, No 105, 1965) in her Catalogue of Bright Nebulae notes that this nebula is very bright, more prominent on the blue POSS plate and has a maximum size of 10' x 8'.

Bernes, C. (1977)

Bernes, C. (1977) A catalogue of bright nebulosities in opaque dust clouds.

The nebula is also catalogued as Bernes 39 in his Catalogue of Bright Nebulosities in Opaque Dust Clouds. He describes it as a reflection nebula 8' across, appearing very bright on the blue plate. Bernes notes that the object is also included as No. 167 in the 1963 catalogue by Dorschner and Gurtler. He notes that the nebulosity is seen in the centre of an approximately circular dust cloud, made up of Lynds 1170, 1172, 1173 and 1174, which together span 55' x 30' (north-south by east-west.)

Doig, P. (1926)

"A Catalogue of Estimated Parallaxes of 112 Nebulae, Open clusters and Star Groups", Vol 36 (4), p 107-115.

"bright and dark nebulosity with seventh magnitude star." He gives the approx. diameter as 12x10 arcmin; obscuration is about 35 arcmin diameter.

Magakian T. Yu. (2003)

= DG 167, [RK68] 105, VdB 139, Bernes 39, N7023, GN 21.01.0, Ced 187, Other designations: V380 Cep

Class: C (reflection neb)

Sulentic & Tifft (1973)

(Sulentic and Tifft 1973) notes that this is a 7.0 mag cluster associated with nebulosity.

Photo index

by Jim Lucyk: Sky&Tel. 9/85 p210, Astronomy mag. 4/82 p103, Deep Sky #7 Su84 p27, Burnhams V1 p620, Deep Sky #20 Fa87 p22, Vehrenberg's Atlas of Galactic Neb-2 p113.

Modern observations

Walter Scott Houston

Houston notes that this is "one of the brightest reflection nebula ... it is centered on a 6th magnitude star that is easily seen in binoculars. From my earliest days as an observer I have notes that refer to the nebula as "real bright" and question why it is not plotted on Norton's Star Atlas. I suspect it is an easy object for big binoculars."

Sanford (1989) Observing the Constellations

Sanford notes that it is a medium-bright glow, which begins to show some dark material silhoutted against the glow with a 10-inch or larger telescope.

Harrington, Phil (1990)

Harrington, P. (1990) An observer's guide to diffuse nebulae – II. Sky&Telescope, July, 97.

Tom Lorenzin

Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "7.1M; 18' diameter; bright reflection nebulosity surrounds 7M star; P-filter enhances detail in nebula; 3 degrees SW of 3.5M DBL ST Alfirk (Beta CEP)."

Brian Skiff

15cm - lg losfcbr neb around m7 *. neb fades smoothly from * and consp-br only in ~8' diam. 35' diam around * is notably blank of fld *s, best shown in 50x/1.2-deg fld, but this is not merely blank or blacker than surroundings, but faintly luminous like patches of hi-lat 'cirrus' on POSS prints. most consp * nr m7 * is m13 * at ~2'.5 in pa165. no cluster as per U2000. 195x shows maybe close comp to br * in SW quad at 5"(?). rich flds N, E, & W, but not S. BS, 8Sep1991, Anderson Mesa.

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The Messier objects

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