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RA: 03h 33m 14.6473s
Dec: −25° 52′ 17.984″
Ch: MSA:356, U2:312, SA:18
Type: planetary nebula
Mag: B=10.99, V=11.2
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This planetary nebula, although bright, was mysteriously missed by both Dunlop and John Herschel. It was found in 1857 by Lewis Swift and later by August Winnecke.
Observations of southern nebulae. Transvaal Observatory Circular, No 2, 13.
Innes, 1909 December 8: "An oval nebula, large but faint, surrounding the 8.9mag (9.4photo) star CPD -26°389. The longer axis is 45°-225°. This diffused nebula is as easily seen in the 2-inch finder as in the 9-inch."
F, L, 9'x5', central star not nebulous, but immediately surrounded by dark absorbing matter. Probably planetary like the 'Owl' nebula.
Knox Shaw, H. (1915) Note on the nebulae and star clusters shown on the Franklin-Adams plates. M.N.R.A.S., 76(2), 105-107.
Comments on papers by Harding (MNRAS, 74(8)), and Melotte (MemRAS 60(5)) describing objects foundon the Franklin-Adams plates; compares with plates taken with the Reynolds reflector (Helwan Obs Bull. 9-15):
NGC 1360 is not a spindle; it is 6' x 3' and probably like the Owl. [previously included in Class II-Spindle-shaped Nebulae]
(Sulentic and Tifft 1973) notes that this is a planetary nebula.
Q.J. R.astr.Soc vol 21, p82-92 [09.16.1] notes that the central star of this planetary is a spectroscopic binary.
Marling, J.B. (1986) In pursuit of planetaries. Sky&Telescope, Jun, 631.
by Jim Lucyk: Sky&Tel. 12/86 p669, Burnhams V2 p904, Galaxies (Ferris,1982) p102, Astronomy mag. 11/87 p106.
From: "Neat Southern Planetaries - VII."
This month we move away from the Milky Way to the realm of the galaxies. Two bright and interesting planetaries, NGC 1360 and NGC 1535 are particularly easy to find. Both show something different regardless of the aperture in use. I have also selected some galaxies in the Fornax II cluster that are not commonly observed by amateurs.
NGC 1360 /Mink 1-3/ VV10/ PK 220-531 (03332-2552) is located in the northeast corner of Fornax, close to the Eridanus border. It is among a very few planetaries well beyond the galactic plane. This planetary is both large, bright and unusual, and is clearly visible in a 7.5cm. telescope. Visual magnitude is measured at 11.6, with a 'B' Magnitude of 11.5. Burnham's Celestial Handbook Vol.2 (See Photo. pg. 904.) and AOST1 both incorrectly state that NGC 1360 planetary nature is uncertain. The description in AOST2 is shorter than AOST1, since the recent discoveries since 1968 has made most of Hartung's original text irrelevant. An O-III filter does wonders for this object, as most of the light emitted is at this wavelength. The coloured AAO slide, also featuring in AOST2 on pg.242, is a source of wonder - especially for the greenness of the object. To quote from the slide set 'Stars and Galaxies IV' produced by the AAO;
"For reasons that are not understood , NGC 1360 defies all these conventions, yet its colour still clearly identifies it as a planetary nebula. The green hue is oxygen, excited by the hot central star, and to the north east of the nebula is a faint red smudge, probable traces of material ejected before the star became a true planetary nebula."
NGC 1360 lies in a particularly spartan field. At first glance it appears as a large but brightly elongated nebulosity along PA 25O -205O. Using an O-III filter it looks much brighter, but unfortunately reveals little structure. Nearer the centre, and slightly following, is a 9th magnitude star (Photo. Mag. 9.6) that is not the central star. In size the planetary is larger than most. Observations by to Scott Mellish (Universe 43,12 & 44,1 pg.5.) states clearly;
"NGC 1360 is a good example of what an [O-III] filter can do to bring out detail in most planetary nebulae. In sketch! (pg.22.) the oval shaped object sports two lobes either side... which are a touch brighter than the central regions of the nebula. .... This is an exquisite object deserving of close observation even without an [O-III] filter for it is brighter than you would expect it to be. .... A large and splendid object."
Most of the literature states a size about 390"sec.arc., though photographically it appears as a 'football' structure some 6.0'x4.5' (360"x270"sec.arc.). Visual diameter of the outer edge I estimated to be closer to 200"x170"sec.arc., but this is likely aperture dependant because the brightness only gradually fades when approaching the edges. Visually, the northern portion is slightly brighter away from the 9th magnitude star. Throughout the nebulosity is evidence of darker matter covering most of the brighter nebulosity - especially in a north-south direction. This can be easily seen in a 30cm. Using adverted vision, I thought I could detect a small dark knot about 90"sec.arc. to the NNW. The 'reddish' ejecta mentioned in the AAO quote is located at about 100"sec.arc. from the planetaries centre at PA345O (NNE), and is listed as a galaxy within Mitchell's catalogue of faint galaxies - MAC 0333-2548. This object is invisible to all amateur telescopes, though some may wish to try to see it! Another galaxy lies along the same position angle, but twice the distance from the northern edge of the planetary. Known as MAC 0333-2547, this 15.7 magnitude object should be visible in a 40cm. or 50cm. Dobsonian as a tiny inglorious smudge. (An image of the object can be seen in the photography on pg.242 of AOST2 in the top left hand corner.)
Until the early 1980's the classification of NGC 1360 was uncertain, but later it was classified as a Class III - defined using the Volrontov and Velyaminov scheme as an 'irregular disk'. This object is similar in structure to NGC 3195 in Chameleon or even NGC 2610 in Hydra. Dennis di Cicco described the planetary in S&T June 1986 (An exposure taken by Dennis di Cicco also appears on pg.632 of the same S&T using Fujichrome 400 and a 17.5" telescope.) His description follows;
"NGC 1360 is about as large as M27, though much fainter. Its large diameter and relatively high integrated magnitude make it visible in a 12x80 finder. It appears quite elongated and the 11th magnitude central star stands out well."
Within the nebulosity are four stars - the 9th magnitude field star, two 11th and 12th magnitude stars to the south, and one white star toward the west at PA 110O. The 11.35 magnitude ('B' Mag.=10.96) western star is the Planetary Nebulae Nucleus or PNN, and listed in the Hipparchos Catalogue as HIP 16566. Eleven reputable reference sources, state this PNN has a visual magnitude ranging between 11.0 and 11.6, so it is possible that the PNN is a suspect variable. Obviously, the star is not central to the nebulosity. This star has a spectra was sdO - indicating a spectroscopic binary from the observed duplication of the spectral lines. Later spectra determine the PNN to be a DA-type white dwarf with a mass of 0.55 Solar Masses. In 1982, the IUE (International Ultra Violet Explorer) observations showed NGC 1360 was more energetic in its UV flux than normal planetaries and in the same year, the first published temperature was given as 88 000OK. Further observations in 1983, from both the ESO and La Silla in Chile, determined from the (very low) helium abundance a Zanstra temperature 66 000OKą 15 000O. By 1989, further observation of the HeII emissions, produced a hotter 77 000OK. Oddly, the calculated absolute magnitude is given as +3.6 (twice that of the Sun), while similar references state the luminosity is about 1 000 times more luminous than the Sun.
In regards the gas shell - the planetaries' inner gas is expanding at 27kms-1, while the bulk of the visible nebulosity is expanding at a more pedestrian 7kms-1. Radial velocity measures show that the object is moving towards us between +43kms-1 and +53kms-1. Recent estimates of distance, using the most accurate result to date by Tylenda and Stasinska (1994), places the planetary as close as 300pc. (980 light years). This value is also quoted in AOST2. If this is so, the actual size of NGC 1360 subtends a true diameter of some 0.33 parsecs or 1.1 light years.
Overall, this planetary is really worthy of a glance.
Surrounding Field of NGC 1360.
Within several degrees of NGC 1360 are a 'fist-full' of galaxies visible for medium to large apertures in dark skies. I have selected a few interesting ones that observers may like to have a look at. All are in the eastern portion of the Fornax II Cluster. This cluster name is really a misnomer, as most of the galaxies are in the constellation of Eridanus. NGC 1395, in Eridanus, is an interestingly bright elliptical galaxy that rarely gets a mention most amateur text. All my descriptive texts never mention them - likely just because they are not as bright nor as famous as the more southern Fornax Cluster some 10O further south! (Note: None of these objects are contained in the Fornax Cluster.)
James B Kaler writes: "It is a most unusual object, one of the few known large, high-excitation planetaries .. analysis of the spectrum sets a lower limit for the central star's temperature of 85,000° K, and the luminosity is at least 540 times that of the Sun. .. from its brightness and angular diameter (over 6 arc minutes) I estimate that NGC 1360 is 1,100 light years away. Its diameter is over 2 light-years, roughly twice as big as the famous Ring Nebula in Lyra and about half the size of the largest planetaries known."
Houston notes that from a light-polluted site he could not see it with his 4-inch refractor, but glimpsed it with a fast 5-inch refractor.
Houston calls this "the sole planetary nebula in Fornax suitable for amateur telescopes. It's readily accessible at northern latitude since it lies at the same declination as Antares ... 'Medium brightness, large, oval, unconcentrated. Quite a glowing cloud' wrote Californian Todd Hansen. 'Must be 7th or 8th magnitude overall, and a noteworthy object.' " Houston searched for it with his 4-inch fich-field reflector from Southern California, and was "amazed by how easy it is to spot this 6' diameter planetary." In 1972 he wrote: "This dim glow surrounding a 10th mag star was discovered about a century ago by a couple of famous comet hunters, Lewis Swift and August Winnecke. This nebula is oval, being about 7' by 10' and elongated in a north-south directiojn. I have not been able to see NGC 1360 in my 4-inch though a tantalizing glimpse was had with a 5-inch moonwatch scope. Yet, Sagot and Texereau state that NGC 1360 has been seen in a 2.2-inch refractor. About 0.4 degrees to the northeast and the same distance to the northwest are 6.5 magnitudes stars."
William P. Clarke (San Diego, California, USA) writes in The Webb Society Nebulae and Clusters Section Report No. 10, July 1992: "Oval object with a major/minor axis ratio of slightly less than 2:1; elongation in approx. PA 15 degrees. The northern end is brighter than the rest of the nebula. The central star is about mag 11. Very large object, about 8' long. (10-inch f/4.5, x63)."
Tom Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "6'x 4.5' extent; surrounds 9M star; large, faint and TOUGH! 50' to NNE is SP GAL N1371 (12M; 5'x 3.5' extent) soft ellipse with brighter center; 90' to NE is SP GAL N1385 (12M; 2'x 1' extent) a soft, centerless blur."
Steve Coe, observing with a 13" f/5.6, notes: "Faint, pretty large, no detail seen at 100X. The UHC filter helps provide some contrast with the backround in my 17.5" f/4.5 Dobsonian. Using the 13" f/5.6 on a driven mount, this planetary is pretty faint, large, elongated 1.5 X 1 in PA 45, the central star in always visible at about 11th magnitude and several dark markings are seen with the UHC filter installed at 100X. This object can be seen without the UHC, but it helps quite a bit."
Observer: Yann POTHIER (France) Your skill: advanced (many years) Object: NGC 1360 (PK 220-53.1; PN G220.3-53.9; M1-3, ARO 208) Category: planetary nebula Constellation: FOR Object data: Vmag=9.4; 460"x320"; type III; central star of Vmag=10.4 (PPM 246372); discovered by Swift in 1857; ELCAT: [OIII, 496+501nm] = 8.5 x [Hbeta, 486nm]. RA/DE: 03h33.30m, -25°51.' (2000.0) Date and UT of observation: 02 November 1991 Location & latitude: La Clapiere Obs. (France, latN44 40 00, longE06 27 36) Site classification: rural, alt.1650m (5500ft) Limiting magnitude (visual in UMi): - Transparency (1 to 5 - best to worst): 1 Seeing (1 to 5 - best to worst): 3 Moon up (phase?): no Instrument: Meade SCT 8" (203mm), F/10 Magnification: 87-100x Filters used: -
Description: at 87x, easy, centered on a mag10-11 star, large nebula somewhat elongated SW-NE; at 100x, very large, about 8' (480") in extent.
PK: pa15 in notes, pa~25 in photo.
Lick: pa20-25, asym, fntr on S. * 4'.1 N m~13.5. no * WNW? nrst are 1'.6 SSW (m14.5) and 3'.4 NW, fntr than m14.5.
8cm - consp haze elong NE-SW that is uniformly br. cen * clearly vis. BS, 29Jan1984, USNO.
13cm - big, br, elong pa30. cen * consp. fairly smooth texture. BS, 23Jan1984, USNO.
15cm - fairly br oval @ 50x w/consp cen *. gradual contrast improvement with filts DS ---> [OIII], which make edge more def and enhance brtness asym btwn NE & SW halves (NE brtr). 80x/140x: 6'.5x3'.5 in pa20, somewhat rectang oval. m14.5 * in SW side. BS, 17Nov1993, LCO.
30cm - 7'x4', delimited by m13 * due N of cen * just off edge, and m14 * on WNW edge. sl dkr patch S on cen *, vsl brtr twd cen, poss vl brtr rim. 125x. BS, 23Jan1984, USNO.
03 33.3 -25 51
17.5: very bright, elongated 3:2 SSW-NNE, 6'x4' diameter, very bright central star mag 10.5-11, almost even surface brightness. Very impressive planetary with or without OIII filter.
1997 Sept 02, Die Boord, 11x80 tripod mounted. Seeing average-good.
Rating: very difficult - impossible. Not sure if seen. Low down, perhaps?
12-inch f/10 SCT (EP: 2-inch 40mm SW 76x 53' fov; 2-inch 14mm UW 218x 23' fov; 2-inch 8.8mm UW 346x 15' fov)
This is a large irregular bright eye-catching planetary nebula. Displays an oval glow in a north south direction. The southern region is slightly brighter. With careful observation it seems to have an uneven texture imbedded and a pale washed out grey colour (218x). This planetary nebula hosts a 10'.5 magnitude star visible with careful observation (346x). A lovely 6th magnitude white star is situated approximately 20' arc minutes to the north west of this planetary nebula.
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 light is lit up by a bright central 9th magnitude star where pale is oval in form and well defined as a whitish mist of light at 75x.This planetary nebula measures 5.7'x 4.7'.Chart No. 198, NSOG Vol.1.
Instrument:12-inch Dobsonian Reflector Telescope.
Sky Conditions:The fainter parts of the Milky Way are barely visible with the naked eye.
Transparency Of The Sky:Haziness only visible on the horizon.
Seeing:Atmosphere stable with little interference.
Object Type:Planetary Nebula.
First Impression:This object looks like a planetary nebula.
Chart Number:No.14(Extract taken out of "Atlas of the Night Sky").
Size:26mm Eyepiece:Field Of View:57'/7= 8.1'.
20mm Eyepiece:Field Of View:50'/6= 8.3'.
8.1'+ 8.3'= 16.4'.
Size in Arc Minutes:8.2'.
Planetary Nebula is 8.2'* 4.1'.
Brightness Profile:From the central nucleus of this planetary nebula this nebula grows brighter.
This planetary nebula's round oval shape is lit up by a 9.4 magnitude star in the center of this nebula.This nebula however has a pale-white structure in appearance.
The Messier objects
The Bennett objects
The Caldwell list
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