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RA: 13h 51m 3.27s
Dec: −51° 12′ 20.6″
Ch: MSA:971, U2:430, SA:21
Type: planetary nebula
Mag: B=11.5, V=10
Discovered by John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "A very singular object. At first I thought it an ill seen double star; 12..13 = 12..13 mag; distance 2 arcseconds; but not being able to get it into focus I applied 320 power; which showed it as a hazy, rather elongated, planetary nebulous disc, as if a double star all but obliterated. It is positively not a star. The field is full of stars, two of which ... are equal to this object in light, but 320 shows them both quite sharp. It is a difficult object to find, and unless in a good night for definition (this is superb) it could not be recovered. The place is well taken. The stars in the neighbourhood (laid down in a diagram made at the time) are - 1 the neb, 2=3=4 nearly equal, and 14th magl 5=15th mag; 6=7 12th mag. It is the smallest and most difficult planetary nebula I have ever seen ... (N.B. By this figure [figure 15, plate VI) it would seem rather to belong to the class of double nebulae or double stellar nebulae of the utmost remoteness, than to that of planetary nebulae, properly so called.)"
A photographic survey of bright southern planetary nebulae. M.N.R.A.S., 110(5), 429-439.
The RNGC (Sulentic and Tifft 1973) notes that this is a 12.0 mag planetary nebula.
From: "Neat Southern Planetaries - III."
NGC 5307 / PK 312+10.1 (1351.0-5112) (Centaurus) can be found lying 0.8O east and 0.1O slightly south, of the 4.7 magnitude star M Centauri. (2.3O NE of Epsilon ( ) Centauri and next to the Globular Star Cluster; NGC 5286). A telescope as small as 10cm. will identify it with some certainty, although David Frew (UNIVERSE June 1986 pg.14) states that he thinks it could be seen in a good 75cm. The photographic magnitude of the nebula is measured at 12.1, but is brighter in visual magnitude.
Telescopically, this small but slightly oval-shaped planetary can be observed as a 12th magnitude bluish 'star', that on closer inspection appears as a small disk. AOST2 states that in good seeing condition it appears as hourglass, which I admit I have never seen visually. Faint structure are revealed with high magnification and especially with an OIII filter. Its diameter is c.10"-12"sec.arc., with a high uniformity of brightness across the entire disk. Much larger telescopes do not add to its apparent diameter. The actual PNN is not visible in small to medium apertures, having a visual magnitude of 14.6.
Distance is estimated by Hartung as 2 400 pc. or 7 800 ltys., though the minimum distance upon recent calculations makes it perhaps as close as 1 900 pc. The entire mass of the nebulosity is estimated to be ~0.45 Solar Masses.
Nearby Fields of NGC 5307.
Burnham calls this a 12th mag planetary in Centaurus, 15 x 10 arcseconds, pretty faint, small and slightly elongated.
Hartung notes that "in a profuse star field is a small planetary nebula elliptical in PA 160 about about 10 arcseconds across ... with a 3-inch .. the object looks merely like a small star. The light is even with rather diffuse edges and no central star."
QBS: OX, but there does seem to be a * on the NW edge. need lg scale photo.
15cm - fairly br non*ar neb @ 80x, m10-10.5. dramatic [OIII] enhancement,
vstrong w/UHC. 195x: seems circ 15" diam and annular, but there is a
m13.5(?) * vclose to NW edge, and a consp *-like spot in S side of ring.
cen * not obvious. BS, 23Feb1990, LCO.
1995-05-28: 11x80.Technopark. 20:15 SAST. Hazy sky, thin clouds. Not visible in binoculars.
Sky Conditions:The fainter parts of the Milky Way are barely visible.Haziness only visible on the horizon.Atmosphere stable with little interference.
This planetary nebula's tiny oval like disk is visible at 214x which is fairly bright and illuminated.This nebula has a pale bluish green structure which has a hazy soft glow at 167x and is well defined.This planetary nebula measures 1.2'x 1.2'.
The Messier objects
The Bennett objects
The Caldwell list
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