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RA: 17h 29m 20.44s
Dec: −23° 45′ 34.2″
Ch: MSA:1394, U2:338, SA:22
Type: planetary nebula
Mag: B=16.6, V=9.9
Synonyms: H IV-011
William Herschel observed it in 1784 with his newly completed 18.7-inch f/13 speculum telescope. He called it "pB, R, pretty well defined planetary disk, 30 or 40 arcseconds diameter."
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. Exactly round, pF, 12 arcseconds diameter, well-terminated, but a very little cottony at the edge, and with a decided darkness in the middle, = star 10m at the most. Few stars in the field, a beautiful specimen of the planetary annular class of nebulae (fig 4, Plate VI)."
Burnham, S. W. () "Measures of planetary nebulae with the 36-inch equatorial of the Lick Observatory", Pub. Lick Obs., vol 2, p159-167. "This is an annular nebula and very much like the well-known example in Lyra, except in brightness. The longer axis is in the direction of 33° and the extreme diaemter on that line is 31''. Herschel has a drawing in Cape Observations. I am not aware of the central star having been seen before."
pB, S, R, annular, fainter on south following edge; faint star in centre and several in ring; possibly nebulous in centre.
The RNGC (Sulentic and Tifft 1973) notes that this is a 14.0 mag planetary nebula.
Photo Index by Jim Lucyk: Deep Sky Monthly 2/82 p7, Deep Sky #23 Su88 p27.
Houston notes that this planetary is "one of the easier kind. About 28 arcseconds across, this 10th mag object lies in a sparse field, facilitating its identification." He recalls observing it from Mexico with 7x50's "and was surprised to find it easily. The greenish tinge characteristic of planetaries was obvious, and the seemingly starlike object looked brighter than its listed diameter, 10.
Steve Coe, in "SACNEWS On-line for July 1996", using a 13-inch reflector, notes: "NGC 6369 is at 17 29.3 and -23 46, which puts it within the ``Bowl'' of the dark Pipe Nebula, so there are few field stars surrounding this planetary. At 220X in the 13" it is bright, large and little elongated 1.2 X 1 E-W. This planetary is much brighter on the north side and is annular with averted vision at 220X. It was immediately obvious at 100X and was light green at all powers. On a great night in the Central Mountains, with 7/10 seeing and 9/10 transparency, I saw the annular hoop of this nebula easily and my notes say the north edge is brighter at 220X. Raising the power to 330X did not show off any new details, only made the light green color less obvious. I have never seen the 16th magnitude central star at any time. The SAC database says that the nickname for this object is the ``Little Ghost,'' I have no idea why this planetary would acquire that name.
Steve Coe, using a 13" f/5.6, notes: "Bright, large, little elongated 1.2 X 1 E-W. This planetary is much brighter on the north side and is annular with averted vision at 220X. It was immediately obvious at 100X and was light green at all powers. This object is located within the "Bowl" of the dark Pipe Nebula, so there are few field stars. Large scopes work well on this object. My old 18" f/6 Dobsonian at 175X will show a central dark spot and at 300X this object starts to look somewhat like the Ring Nebula. 13" Camp 613 7/10 see, 9/10 trans--100X nice planetary inside a dark nebula. 220X--pretty bright, pretty small, round, annular, north edge brighter, no star seen, light green. 330X--color much fainter."
Steve Coe: [amastro] Summer Planetaries
Well, the clouds went away for a while and I got out to do some real observing. What a nice break! Here are some of the notes of a few summer planetaries that I observed. For those of you still clouded out, have faith, for I have seen the Milky Way and it still exists, honest.
NGC 6369 in Ophiuchus Eagle
Eye site S=7 T=8 13" 100X--obviously non-stellar 150X--mostly annular "horseshoe" shape, a not quite complete ring of nebulosity. It is brighter on the north side and the south side is the opening in the horseshoe. Ken Reeve's 20" f/5 with the 8.8 mm EP a complete annulus with a central star held about 30% of the time. A light grey-green. Fills in the ring with faint nebulosity, more obvious with averted vision.
:"This is a moderately bright planetary nebula which is almost 1' in diameter. It appears as a grey puff of light which, with averted vision, has a darker center suggesting annularity (a ring shape). Try high powers on this object."
In Ophiuchus lies this 11th magnitude smoke ring about 30" in diameter. The surrounding starfield is rather barren, but the planetary should stand out well because of its relatively large size.
Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "13M; 30" diameter; 15M center star; faint halo doubles diameter; 30' WNW of 5M 51 OPH; S-shaped dark nebula B-72 1.3 degrees due W."
Instrument:12"Dobsonian Reflector Telescope.
Sky Conditions:The fainter parts of the Milky Way are barely visible.
Transparency of the Sky:Haziness only visible on the horizon.
Seeing:Atmosphere stable with little interference.
First Impression:Planetary Nebula.
Chart Number:No.18(Extract taken out of "Atlas of the Night Sky").
Brightness Profile:Medium Surface Brightness.
Challenge Rating:Difficult to observe in a small telescope,but noticeable in a large telescope under dark skies.
Overall Shape:Oval and well defined.
Is a disk seen? Yes,a medium disk is seen as a small smoke ring at 214 magnification.It almost resembles the Ring Nebula in Lyra but is somewhat smaller and fainter.
Is the edge sharply defined? No.
What colour is the nebula? Dark Green.
Is there a central star? No.
Observing site: Pinnacles overlook
[17h 29m 18s, -23° 46' 0"] Like a small, round version of M 57, the ring.
The Messier objects
The Bennett objects
The Caldwell list
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