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RA: 09h 16m 10s
Dec: −36° 37′ 6″
Ch: MSA:923, U2:364, SA:20
Ref: DAML02, Collinder (1931), Archinal&Hynes (2003)
Type: open cluster, 31mn
Mag: B=?, V=8.2
James Dunlop discovered this object from Paramatta, New South Wales, and included it as No. 564 in his catalogue of 1827. Using a 9-inch f/12 telescope, he described it as "a pretty large faint nebula of a round figure, 6' or 8' diameter; the nebulosity is faintly diffused to a considerable extent. There is a small nebula in the north preceding side, which is probably a condensation of the faint diffused nebulous matter; the large nebula is resolvable into stars with nebula remaining."
Discovered by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "A very curious object which reminds me strongly of Messier's 46 [NGC 2437] and IV.39 [NGC 2438]. It is a rich cluster of the VI class; stars 12..14th mag; about 8' diameter; gpmbM; all but a sort of vacuity, in which is situated a pB, R, neb; 40 arcseconds diameter; of a character approaching to planetary, having its edges shading off very rapidly, and being but very little brighter in the middle." On a second occassion he called it "pB, R, vgvlbM from the edge, where it fades off very suddenly; being all but a planetary nebula. Situtated in a sort of vacancy in the preceding part of a fine rich cluster of stars 11..15th mag, which nearly fills the field. It is a fellow object to Messier's 46, with its enclosed planetary nebula IV.39. Plate V, fig.8."
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 9' and the class as 2 2 m.
Raab, S. (1922) A research on open clusters. Lund Medd. Astron. Obs. Ser. II, 28, 1.
Discussed, based of F-A plates.
Doig, P. (1925) Notes on the nebulae and clusters in Webb's 'Celestial Objects for Common Telescopes' (Sixth edition, Vol.ii). Part III. Southern Objects. M.N.R.A.S., 36(3), 91.
Galactic and Extragalactic Studies, III. Photographs of thirty southern nebulae and clusters. Proc. N.A.S., 26, 31-36.
pB, S, not planetary, probably of the gaseous structureless variety. Herschel descrbied it as all but planetary.
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
The RNGC (Sulentic and Tifft 1973) notes that this is a 10.0 mag open cluster.
Harrington calls this a rather unimpressive 8th magnitude cluster of about 40 faint stars. He writes: "however, after careful examination, observers will find more than initially meets the eye. On the west-northwest edge of the cluster, casting a gray image, lies the dim planetary nebula NGC 2818A."
Houston notes: "This cluster contains about a score of stars in an area 9' in diameter.
Sanford notes that this 8.2 magnitude cluster is about 9' across and consists of "about 30 faint stars." He adds that at least an 8-inch telescope is needed to see the combination of cluster and planetary nebula (NGC 2818A) well.
Ostuno calls it a cluster of about 40 stars, including a planetary nebula believed to be an actual cluster member.
Steve Coe, observing with a 13" f/5.6, notes: "This same NGC number is applied to an open star cluster and a planetary nebula involved within that cluster. The cluster is pretty faint, pretty large, somewhat elongated, 16 stars were counted across a hazy backround at 135X on a night I rated 5/10, on a much better night (7/10) I called the cluster pretty bright and could resolve 34 members at 150X. The planetary nebula is easy at all powers on the Eastern edge of the open cluster. A few dark lanes are seen in the planetary at 165X, it is light green at all powers."
PLANTARY NEBULA AND CLUSTER
RA: 09h16m54s - DEC: -36o37'0" - Magnitude: 8.2 - Size: 9'
Tel: 16" S/C – 184x – 290x - Date: 25 November 2009 – Seeing 5.
NGC 2818 is a lovely stringy cluster, and appear to be in a slight oval shape from north-west to south-east. Around 35 members of between magnitude 12 and 13 made a standing impression against a sparse star field. A few brighter stars concentrate in the northern part of the star field. The beauty of this object however, is the proven planetary nebula situated near the eastern edge of the cluster. Planetary nebula PN G261.9+08.5. appears as a small round haze easily seen imbedded between the cluster stars. With real high power a divided pair of lobs can be glimpse from east to west, sport a typical dumbbell shape. The initial references indicate the planetary as NGC 2818 and the cluster as NGC 2818A, SIMBAD does agree; but in the NGC-IC catalogue they're are both listed as NGC 2818 without commentary.
1994-02-13 02:00 Die Boord, 11x80's tripod-mounted. I had expected this cluster to be much brighter, and was surprised when it was only clearly seen with averted vision as a soft, round glow.
Sky Conditions:The fainter parts of the Milky Way are barely visible.Haziness only visible on the horizon.Atmosphere stable with little interference.
At both 57*and 75*this open cluster is well detached and most of the stars are nearly as each other.All the stars in this open cluster are slightly concentrated towards each other.This open cluster measures 7.1'*2.3'.The central stars in this cluster is equally bright as the stars on the far outskirts of this open cluster.
The Messier objects
The Bennett objects
The Caldwell list
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