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RA: 20h 16m 23.97s
Dec: +30° 33′ 53.2″
Ch: MSA:1171, U2:119, SA:9
Type: planetary nebula
Mag: B=?, V=?
Synonyms: H IV-013
William Herschel observed it in 1784 with his newly completed 18.7-inch f/13 speculum telescope. He called it "exactly round, of an equal light throughout, but pretty faint, and about 1' in diameter...the edges are pretty well defined." and also as "pF, exactly round, of equal light, the edges pretty well defined, 1' diameter."
Burnham, S. W. () "Measures of planetary nebulae with the 36-inch equatorial of the Lick Observatory", Pub. Lick Obs., vol 2, p159-167. "Considerably darker in the middle, and apparently belongs to the annular class. The faint star within is not central but is near the preceding side. There are many stars nearer the nebula than the 11m comparison star.."
The RNGC (Sulentic and Tifft 1973) notes that this is a 14.5 mag planetary nebula.
Photo Index by Jim Lucyk: Deep Sky #7 Su84 p9.
Houston notes that this nebula in Cygnus should be invisible in scopes smaller than about 10 inches. He notes that it is bright and easy in a 12-inch, and has even glimpsed it in a 4-inch on a good night. He adds: "This nebula is considered to be as bright as mag 12 by some amateurs."
Hartung notes "William Herschel . . did not notice the annular character, which indeed is not easy to see, although 30cm will show it in good conditions. It is faint, round, about 45arcsec across in a field sown with stars . . this object needs care in finding with a good aperture."
PK: spot sup NW side (pa330) is almost certainly a star.
15cm - fairly f puff w/o filters @ 80x. gradual enhancement going from DS to [OIII], although UHC and [OIII] are not dramtically different. 140x: annular w/hole about 1/4 total diam, which is 30". ring brtst along NW periphery, which shows both direct and w/filters, so seems to be nebulous and not sup *. no cen *. BS, 15Oct1990, Anderson Mesa.
25cm - 180x/240x: fairly f, circ. smooth grey disk well-def. indef annularity. no nrby *s of note.
30cm - modlosfcbr, fuzzy annulus 45" diam. N side brtr, w/perhaps * on outer edge in pa330. greyish. 149x/238x.
The Messier objects
The Bennett objects
The Caldwell list
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