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RA: 17h 22m 15.66s
Dec: −38° 29′ 3.5″
Ch: MSA:1439, U2:376, SA:22
Type: planetary nebula
Mag: B=?, V=?
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Discovered by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "annular nebula. A delicate, eF, but perfectly well-defined annulus 15..20 arcseconds diam. the field crowded with stars, 2 of which are on the neb (See fig 3, plate VI)." On a second occassion he called it "a beautiful, delicate ring, of a faint ghost-like appearance, about 40 arcseconds diam; in a field of about 150 stars, 11 and 12m and under. In it is one star 12m very conspicuous, and one 15m much less so. Near it are 2 stars 14 and 15m, and s of it at dist 1' is another." His third observation was recorded as "eeF and difficult object, among a crowd of milky way stars. My attendant JS saw the darkness in the centre and the stars as described."
"Extract of a letter from Sir John Hershel to Francis Baily, Esq., dated Cape of Good Hope, October 22, 1834", Monthly Notes RAS, 3, 75-77.
"... A brief recapitulation of a few of the more interesting objects and remarks which have fallen under my notice may not be unpleasing to you. ... On the 28th of June I discovered an annular nebula in RA 17h 10m 36s, NPD 128° 18' (all the above places are for January 1830). It is exactly round, and perfectly well-defined, diameter 15 arcseconds, very faint, like that in Cygnus, and situated among an immense crowd of stars."
Sketched and described.
Observations of southern nebulae. Transvaal Observatory Circular, No 2, 13
"Cometary nebula, nearly round, 9.2 mag. Stars involved. Diameter 40''. Nucleus is N.f. H's place is good" (R.I., 1909, July)
"A ring nebula with nebulosity within ring, slightly elliptical, 135°-315°, brightest in about 45° A star 11.0 mag is situated just within ring in direction 60° and a very faint star (13.0m) appears to be on the ring in about 225°. (W.M.W.)
F, pS, R, an annular nebula with two stars in the ring; one or more very faint stars in centre of ring, but no nebulosity is shown, such as was drawn by Lassell (Mem. RAS 36) and observed at Johannesburg (T.O.C. 2).
Planetary. A well defined and narrow ring, with a central star of 16-17 magnitude. Along a diameter of the ring in PA 25deg is a line of stars, so straight as to suggest some connection with the nebula rather than a chance superposition. The two brightest stars are at opposite ends of this line, that to the n. being just inside the ring and the s. one on the ring itself. Between the central star and this s. star is first (distant 5'' from the former) a star 17-18mag, and then either a still fainter star or possibly a small piece of nebulosity. The ring is about 40'' in diameter, and the background inside appears quite dark with an exposure of 60 min.
by Jim Lucyk: Sky&Tel. 10/69 p227, Deep Sky #15 Su86 p13.
(Sulentic and Tifft 1973) notes that this is a planetary nebula.
Observer: Scott Hogsten; Your skills: Intermediate (some years); Date/time of observation: Aug 19,1998 10:15 EDT; Location of site: McConnelsville, Ohio (Lat 39N, Elev ); Site classification: Rural; Sky darkness: 6.5 Limiting magnitude; Seeing: 8 1-10 Seeing Scale (10 best); Moon presence: None - moon not in sky; Instrument: 12.5" f5 Dob; Magnification: 125x, 150x; Filter(s): ; Object(s): NGC 6337; Category: Planetary nebula.; Class: ; Constellation: SCO; Data: mag 12.3 size 38"x22"; Position: RA 17:22.3 DEC -38:29
Description: Small and faint PN, no detail seen. This nebula was seen using averted vision and noticing it blinking in and out of view
Coe, observing with a 17.5" f/4.5 at 100X, notes: "Pretty faint, large, annular planetary nebula that demands high power to see fine detail. At 320X there are two stars involved, the stars straddle a dark area in the center of the object. The UHC filter helps a little. This nice planetary does not seem to get observed often.
16-inch f/10 SCT (127x, 290x)
What a lovely planetary nebula with a lot of detail. It displays real round in figure. The ring shows that the NE and SW sides are thinker. Inside the ring it is small dark halo. A 12.5 magnitude star can be seen inside close to the northern inner ring. The Southern side shows a unique knot or thickening of the ring structure. Less than 1' in size. The field west of the planetary is very busy with faint stars extended for more than 8'.
The Messier objects
The Bennett objects
The Caldwell list
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