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Type: supernova remnant
Mag: B=?, V=?
Size: 60′ x 8′
NGC 6992 is part of the Veil Nebula. See NGC 6960 for a discussion.
Synonyms: H V-014
William Herschel observed it in 1784 with his newly completed 18.7-inch f/13 speculum telescope. He called it a "branching nebulosity of about a degree and a half in right ascension and about 48' extent in polar distance. The following part of it is divided into several streams and windings, which, after separating, meet each other again towards the south." In the Philosophical Transactions, 1811, Herschel describes it as follows "extremely faint branching nebulosity; its whitishness is entirely of the milky kind, and it is brighter in three or four places than in the rest; the stars of the milky way are scattered over it in the same manner as over the rest of the heavens. Its extent in the parallel is nearly 1.5 degree, and in the meridional direction about 52 minutes. The following part of it is divided into several streams and windings, which after separating, meet each other again towards the south."
In the 5th edition of Webb's Celestial Objects for Common Telescopes it is described as "large nebulosity in curve. Wolf's photo shows that this and NGC 6960 are probably one large nebula."
Ced 182b (NGC 6992)
Position (1900): RA 21 52.2, Dec + 31 19
Spectrum of nebula: emission spectrum (observed)
Classification: Nebulae without definite relation to certain stars - Detached nebula with discernible structure (eg. NGC 6992)
Notes: "Ced 182 The nebulous wreath in Cygnus. Ced 182 b = NGC 6992 = GC 4616 = h 2092 = H V 14. Disc. 1784."
Bailey, examining a Bruce plate (Harvard Annals, Vol 72, No 2), notes: "NGC 6960, NGC 6979, NGC 6992 and NGC 6995 are parts of the Great Cygnus Nebula."
(Sulentic and Tifft 1973) notes that this is a diffuse nebula.
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.
writes: "[NGC 6992 and NGC 6960] are the brightest portions of the often-pictured Veil or Loop Nebula in Cygnus. ... NGC 6992 lies about two degrees east and slightly north of NGC 6960. Both are thin curved arcs of faintly glowing gas over one degree in length and are best seen in rich-field telescopes on nights of excellent sky transparency. We can only marvbel at how Herschel ever found this extensive nebulosity is his long-focus, narrow-field reflectors."
Notes that European observers "seem fond of the title Cirrus Nebula" instead of the Loop or Veil Nebula. He calls it "fascinating and beautiful. It can be seen quite well in binoculars of at least 50mm aperture ..." He notes using a "22-inch f/8 Cassegrain reflector, with a Daystar 300 filter and a 32mm ocular, and the nebula looked exactly like it does in photographs. It appeared at its best above 52 Cygni [NGC 6960] where the nebula narrows and looks tubular, and over in its eastern portions [NGC 6992], where the loop could be followed for about a degree."
Forbes (Stoke, St. Mary Bourne, Hampshire) observing from Puimichel, France, writes in the The Webb Society Nebulae and Clusters Section Report No. 11, January 1993: "Both nebulosities appear purplish in colour, bright and show much detail. NGC 6992 is smaller, and the UHC filter on NGC 6960 darkens the nebula slightly but reveals more detail. It shows as being long and strandlike with thin strings. (42-inch, x185/x310)"
Bushnall (Hartlepool, Cleveland) observing with a 8.5-inch f/6, writes in the The Webb Society Nebulae and Clusters Section Report No. 11, January 1993: "The western part of the Veil Nebula, visible as a very long arc filling the 70' field. At low power and using the UHC filter, filamentary structure could be seen crossing the whole area."
Notes that NGC 6992 and NGC 6995 "are portion of a great nebulous region including NGC 6960. In rich surroundings there is a broad luminous band crossing the starry field from np to sf, and extending far beyond; it is 5' to 6' wide at the broadest parts, not bright but quite plain and with irregular streaks in it. It is better defined along the north edges and involves many stars and star groups. The nebulous region is evidently complex and varied in brightness, and tails out to a very faint curved thin ribbon south and south-following; the brightest parts may be seen with 20cm."
(e-mail: email@example.com, web: http://www.west.net/~jbc/)
Instrument: 8-inch Dobsonian reflector Location: Carpinteria, CA, USA
Light pollution: light Transparency: good Seeing: fair
Time: Wed Jul 2 09:20:00 1997 UT Obs. no.: 185
As with NGC 6960, I needed to use peripheral vision at 49x to even detect it. It was thicker and shorter than NGC 6960, the Veil Nebula's other major component.
Harrington, P. (1990) An observer's guide to diffuse nebulae – II. Sky&Telescope, July, 97.
Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "7M; East portion of big bubble; includes N6995, N6979 and N6960; all are filaments of glowing gas, the remnant of a supernova; the spawn of minds to come; also visible are other shards of this ill-fated star, between N6992 and N6960; brightest and largest of which is the "ASCOT" 1.75 degrees due W of the N-most part of N6992; use N-filter to gather all the details."
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