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Helix Nebula

NGC 7293, ESO 602-22, PK 036-57 1, PK 036-57, PN G036.1-57.1, Sunflower Nebula, Bennett 129, Caldwell 63, Helix Nebula, GC 4795

RA: 22h 29m 38.55s
Dec: −20° 50′ 13.6″

Con: Aquarius
Ch: MSA:1355, U2:347, SA:23

Ref: SIMBAD

(reference key)

Type: planetary nebula

Mag: B=13.158, V=13.524

Size: ?
PA: ?

Image gallery

Sketches  (3)

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Photos  (5)

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Historical observations

NGC/IC Dreyer (1888, 1895, 1908)

The NGC notes that it was observed by Harding, and describes it as "remarkable, pretty faint, very large, elongated or bi-nuclear."

Wood, H.E. (1910)

Wood, H.E. (1910) Great ring nebula in Aquarius. Transvaal Observatory Circular, No 5, 59.

R.T.A. Innes, 1910 October 3: "A very remarkable object, nearly circular, with a diamter of 11'. It looks like a ring nebula super-imposed on a planetary nebula or like a disk of nebulosity with the outer halves of the north and south segments brighter, with an opening in the ring north preceding.

This object was first seen with the 2-inch finder, in which it was so conspicuous that it was further scrutinzed through the 9-inch. IT was also independently seen and noted on a photographic chart by Mr H E Wood some weeks ago. Hence the description in the NGC "vF" is either incorrect or the nebula is variable; probably variable, for it si not easy to see how such a conspicuous object should have been missed by Messier and the Herschels."

H.E. Wood: "The nebula was first seen on 19th September on casually examining a plate which was being dispatched to England. A rough measurement of its position was made, and the nebula was photographed on 4th October with 60 mins exposure. It appears on the photograph as a broad continuous ring, a little fainter at 135° and 315° than at other parts. It extends across 52secs in RA and 12.6' in Dec. There are three stars within the anchor-ring, clear of the nebula and six on the annulus itself. None of these stars are given in the CPD the brightest of them (the central star) is about 10.5 mag. The postioin of this star, which lies almost exactly at the centre of the nebula, is: [1875.0 RA and DEC given]

The stars CPD –21°,8132,8135 (coarse double) and 8139 form a triangle around the ring."

Innes, R.T.A. (1917)

Innes, in Union Obs. Circ., 1-44, p 345, notes: "Seen in both the 3-inch and 9-inch telescopes. Large, but no detail. Helix or ring not seen. 1917, September 13."

Published comments

Helwan Obs. Bulletin No 9 (1912)

!! pB, 15' in diameter. Wonderful helix.

Helwan Obs. Bulletin No 22 (1921)

!! Planetary. This beautiful object has been already described and illustrated in HOB 9, also in Pub.Lick.Oby., Vol 13. A recent plate shows an additional much fainter loop in n.f. portion, which extends to 15' from the centre of the nebula.

Knox Shaw, H. (1915)

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 7293 is not a spiral; it is also included in Class III [diffuse nebulae], where it properly belongs [earlier authors had listed in as Class I.(c) – Known to be spirals.]

Burnham's Celestial Handbook

Burnham calls it "remarkable, pretty faint, very large, very slightly elongated, annular, diam. 12' with 13th mag central star." He notes that despites its large size (12' x 16') it is faint and has a low surface brightness. He estimates the total magnitude as 6.5.

Burnham adds, "it is said that this nebula was never observed by either of the Herschels with their giant telescopes!" The annular appearace, notes Burnham, similar to the Ring Nebula in Lyra, is not clearly seen visually, but is well shown on long exposure photographs. The general structure resembles a coil with two turns; a much smaller planetary in Draco (NGC 6543) has a very similar pattern.

Terzian, Y. (1980)

Q.J. R.astr.Soc vol 21, p82-92 [09.16.1] notes that this planetary shows multiple shell structure.

Sulentic & Tifft (1973)

(Sulentic and Tifft 1973) notes that this is a planetary nebula.

Photo index

by Jim Lucyk: Sky&Tel. 5/82 p449, Sky&Tel. 6/75 p402, Sky&Tel. 6/84 p581, Sky&Tel. 6/86 p632, Sky&Tel. 7/69 p12, Sky&Tel. 10/68 p270, Sky&Tel. 10/69 p273, Sky&Tel. 10/83 p367, Sky&Tel. 11/69 p308, Sky&Tel. 12/77 p460, Sky&Tel. 12/79 p509, Astronomy mag. 9/74 p24-25, Astronomy mag. 11/79 p81, Deep Sky #6 Sp84 p17, Burnhams V1 p193, 195.

Modern observations

Walter Scott Houston

Houston notes it has a very low surface brightness because of its unusually large quarter degree diameter. "Nevertheless there are reports of it being seen in 7x35 binoculars and 6x30 finders." He notes that it has a total magnitude of 6.5, but because of its great size it has a low surface brightness; "its pale hazy disk is often missed by amateurs who are accustomed to seeking much smaller objects. Averted vision is needed, and the eyepoiece field should be at least half a degree in order to surround the nebula with some contrasting dark sky."

Hartung, E.J. (1968) Astron.Obj.South.Tel

Hartung writes: "This remarkable object ... is a large rather faint annulus about 14' x 12' with a dark centre about 6' across and a 12th mag central star. The brightest parts of the ring as N.f. and S.p., and the faintest part is N.p. where the luminous haze is broadest and four small stars are involved ... the nebula may be seen as a faint round haze with a 3-inch telescope."

Harrington, Phil

According to Phil Harrington, it is a real challenge for a 2- to 3-inch binocular. It has, however, been found easily with a 10x40 binocular, appearing as a faint spherical glow with direct vision.

Phil Harrington (1990, Touring the Universe through Binoculars) notes that "under prime conditions, this celestial smoke ring looks like a round, hazy patch of dim gray light. Giant binoculars hint at the cloud's subtle texture, but the central star will remain unconfirmed. Due to its low surface brightness and large expanse, NGC 7293 is frequently much easier to pick out in the wider fields of binoculars than with comparatively narrow-field telescopes."

Sanford (1989) Observing the Constellations

Sanford notes that it is "large (15' diameter) but faint ... This wonderful object appears like a large, dim smokering in 20x80 binoculars. A dark, clear night is necessary to view it well, when it can be seen in steadily held 7x50 binoculars. In a rich-field telescope with an O-III filter, the contrast is increased, and the object becomes easy to see."

Marling, J.B. (1986)

Marling, J.B. (1986) In pursuit of planetaries. Sky&Telescope, Jun, 631.

Bortle, John (1976)

John Bortle (Webb Society Quarterly Journal, January 1976) using 10x50 binoculars, estimates the visual magnitude as 7.4.

Kaler, James B

James B. Kaler ("The Amateur Scientist", Scientific American, May 1992) notes: "The closest known planetary nebula to the earth, it is a mere 500 light years away. Because it is so old, the nebula is enormous. Furthermore, because it is so close, it covers a region of sky almost half the angular diameter of the full mon . . even with binoculars, Wyrick picked it out as a 'grayish blob' and saw a hint of its ring structure. Using 10-inch scopes, Cadle and Mitchell clearly saw its ghostly ring set among the stars."

Tom Lorenzin

Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "7.3M; 13' diameter; N-filter helps greatly on this!; four faint stars on W side (two NW and two SW); N-filter shows center more rarefied though 13M enter star not visible in interior glow; visible in binoculars!."

Martin, N.J. (IAAC)

(IAAC)Object:- Helix nebula NGC7293 20" Dob-Newt Observer:N.J.Martin Your skill:intermediate Date and UT of observation:03/04 September 1997 02.00 Location & latitude:near Ayr South West Scotland lat 55 24'56" Site classification:bright rural Limiting magnitude (visual):6 (zenith) 4 at altitude 11 degree of nebula Seeing (1 to 5 - best to worst):2 Moon up (phase?):no Instrument:20" f4.4 Dobsonian Magnification:X86 Filters used:Lumicon UHC Object:NGC 7293 Helix Nebula Category:Planetary nebula Constellation:Aquarius Object data:mag 6.5 15'X12' RA/DE:22hr 27' -21 06' "Description: The magnitude is a con trick. The object is half the diameter of the moon and so has a very low surface brightness. Only just visible in binoculars as a featureless disc and looks similar in telescope without the UHC filter. With filter is clearly a planetary nebula with darker centre and broad perimeter ring. The ring is clearly double in the north west and south east quadrants with some evidence of doubling in other parts. The low altitude at my latitude does not help visibility.

Steve Coe

Steve Coe, using a 17.5" f/4.5, notes: "Pretty bright, Very large, annular at 100X. The UHC filter helps the contrast very much. Seen as uniformly illuminated disk in 10X50 finder or binocs. The central hole can be held steady at times, but is generally more prominent with averted vision. There are 5 stars involved within the Helix shape. If you are looking for a real observing challenge for your next observing session, the Helix can supply a toughie! The picture of the Helix on page 195 in Burnham's Celestial Handbook shows a very faint edge-on galaxy at the edge of the Helix Nebula. It is located at the end of the Helix that opens up near a pretty bright star. Using the 17.5" on a night I rated 9/10 at 8000 ft. in the Central Mountains of Arizona, I could just pick it out at 300X. 13" Sentinel 8/10 11X80 easy, bright, large, round, several stars near and involved. 60X nice view, 5 stars involved and nice double star at south edge, center darker, but no "hole". 100X 7 stars involved, still no hole in middle, adding UHC filter makes it a very contrasty view, much darker middle, only 5 stars involved, but nice view. 150X best view, neby is about 60% of the field of view, 11 stars involved, several very faint, north side of nebulosity is brightest. Adding the UHC at 150X shows the middle as very dark, but not completely free of nebulosity at any time."

(unknown)

(PK36-57.1) Mag=7.3. "Helix" Nebula in Aquarius: 22h, 29.6m; -20° 48' The spectacular "Helix" nebula is shown above, as photographed by Dr. David Malin with the 150- inch aperture Anglo- Australian Telescope, and included by permission. We skipped this huge (12 arcminute diameter) object during our overview of Ferguson's planetaries, since we had made a careful study the previous year, while examining objects in order to create "eyepiece view" images for our Waldee-Wood program LUMIVIEW. If we may quote the file written for the program:

Dreyer Summary (NGC): Remarkable Object, Pretty Faint, Very Large, Extended or Bi-Nuclear.

The telescopes that were used by NGC contributors were generally not perfectly suited for visually examining the details of such an enormous object as the helical shell of ionized oxygen and hydrogen gases that comprise the "Helix" nebula. However, some of the visual character of NGC 7293 is described above, although with modern Lumicon O-III and UHC nebular- line filters, even a modest 8- inch telescope is capable of showing about as much detail as a photograph, PROVIDED that: (1) the ocular employed can fit an object half the diameter of the Moon into a comfortable visual field; (2) the eyepiece exit pupil is as large as practical for efficient retinal sensitivity to H-Beta radiation at 4861 Ångstroms; (3) the sky limiting magnitude approaches 6.0 stellar limit or better; and (4) the viewer has fully dark-adapted eyes.

Under less optimal conditions, either due to scope aperture and field of view, or skyglow from light pollution, the nebula's appearance will range from utterly invisible to pale and indistinct. Filters are an essential aid for viewing this challenging object. Indeed, until the availability of Lumicon Nebular Filters, few deep- sky observers had much opportunity of clearly discerning this faint and extremely large object. The best photographs could register the helical shape of the overlapping rings of hydrogen gas, but the eye is not sensitive to the dim levels of H-beta light radiation. Now thanks to nebular filters, the actual shape of the "Helix" can be traced.

In his guide OBSERVING THE CONSTELLATIONS, Professor John Sanford explains: "Planetary nebulae are expanding shells of gas which surround a central star in the final stages of its evolution...They were named by Sir William Herschel in 1785 because of their telescopic similarity to planets...The central star is usually blue and hot...and heats up the surrounding gas shell...as the star fades the gas shell expands...The large (15 arcminute diameter) but faint, Helix is located in southern Aquarius. This wonderful object appears like a large, dim smoke-ring in 20 x 80 binoculars. A dark, clear night is necessary to view it well...with an Oxygen III filter, the contrast is increased, and the object becomes easy to see."

The "Helix" looks different from typical planetary nebulae like the round and fairly even M-97 or NGC-7662. Sanford notes that the broken filamentary structure indicates a rapid movement of expanding gas. Deep photos reveal a faint irregular disk with striations leading outward from the center. The old brightness figure was an integrated visual magnitude of 6.5 (equivalent to a 6.5 magnitude star defocused to a diameter of half the full Moon!) Dr. Jack Marling's new and improved rating is 7.3; yet due to the enormous angular diameter, and the fact that the brightest nebulosity is visible at the outer edges of the rings, the overall surface- brightness is a very low value, calculated at about 11.3 mag/sq. arcminute.

Thus to get a clear eyepiece view: (1) use a very wide-field scope at the lowest magnification; (2) view when the "Helix" is nearest the meri- dian, since its declination is relatively low; (3) use a dark sky site; and (4) be sure to employ a nebular filter. The Lumicon UHC (tm) model accentuates the h-beta radiation line; the O-III filter improves the overall faint background shell of doubly- ionized oxygen. Employ standard broadband LPR (light pollution rejection) filter -- such as the Lumicon DEEP-SKY (tm) model -- for photography.

We are positively shocked and amazed that Ferguson could detect this object with such a low surface brightness using a 3.5" Questar in the light- polluted sky of Houston. Surely only the oxygen- nebula filter permitted this observation to be made: in the Santa Cruz mountains, we have often found the "Helix" to be nearly invisible without the filter, using an 8" aperture scope. Only in a very dark-sky site does this object clearly show up without a contrast-enhancing filter as a broken smoky oval: in such a sky, adding the filter permits examination of the actual apparently-helical coils of nebulosity.

Maloney, Patrick (IAAC)

Observer: Patrick Maloney; Your skills: Advanced (many years); Date/time of observation: 02/Aug/1998 0810UT; Location of site: Palisades-Dows Observatory, Nr Cedar Rapids, Iowa (Lat , Elev ); Site classification: Rural; Sky darkness: 6.0 Limiting magnitude; Seeing: 7 1-10 Seeing Scale (10 best); Moon presence: None - moon not in sky; Instrument: 10" Starsplitter Newtonian; Magnification: x38; Filter(s): OIII filter; Object(s): NGC 7293; Category: Planetary nebula.

Description: Enormous! Totally invisible without the OIII filter, unmissable with it in place. A slightly flattened ring with gaps at the extremities. A brighter patch is visible in the north east quadrant. Central star not seen.

Brian Skiff

PASP 85:224 (Dahn et al.) has UBV for superposed *s. 15cm stars: Dahn #1, #9, #6; others not meas.

8cm - easy @ 20x, no annularity. consp *s N, SE, and SW edges. BS, 15Sep1982, Anderson Mesa.

15cm - f, about 15' diam w/*s embedded in neb and a sl dkning in center.

- lg ,br, & easy @ 30x, obviously annular. sev *s nrby incl pair SW. all filters show improvement: DS wk, UHC & [OIII] give sim but dramatic contrast enhancement. appearance of neb sl different in these two filts: [OIII] seems to give sl fuzzier impression compared to UHC, and outer periphery not so sharp, perhaps an illusion owing to the high contrast here. using filters at 80x for nebula: oval, elong ESE-WNW w/sl tapering at ESE end, which has ill-def border; WNW end fuzzy also, but not so obviously as opposite end. NNE side sl brtr than rest. annulus seems circ w/in oval neb; is dimmer but not as dk as surrounding sky. cen * (m13) obvious at 80x. 140x w/o filts for embedded/assoc *s: m13 * E/sl S of cen * just beyond annulus in neb; m11.5 * NNW two-thirds the way out the ring; m11.5 * SW in ring, not far outside annulus; three *s (m12, 13, m13.5) W & NW of this *. perhaps a few others at threshold, but no others in neb as br as these six (plus cen *). BS, 20Nov1989, Anderson Mesa.

- br lg annular pn @ 50x w/sev *s sup. cen * vis. steady contrast improvement going from DS to UHC and [OIII] filters, but annulus becomes gradually washed out, so halo is most obvious w/DS filt. oval brtst on NNE & SSW periphery. BS, 17Nov1993, LCO.

25cm - oblong w/fairly distinct hole in center. close dbl* on S side of neb. some indistinct detail. BS.

30cm - 149x: vlosfcbr. stars: ten *s in neb incl cen * and companion. brtr band of neb (N-S) on E side btwn two *s. br spots on NW and SW. annularity not distinct. compares w/photo. CBL, Roof.

Contemporary observations

Auke Slotegraaf

2016 October 30, Sunday

Location: Night Sky Caravan Farm, Bonnievale.

Date: 2016 Oct 30, Sunday.

Time: 23:22 SAST

Telescope: Little Martin (4-inch f/6.5 Celestron refractor)

Nice in the 45-mm Celestron Plossl (15x) but better with 19-mm Panoptic (35x). Large irregular nebula, wide pairs of stars outside, several stars inside.

1997 October 02

6-inch f/8.6 Newtonian: 1997-10-02, Franschoek Pass viewing site. Obvious haze and thin clouds, sky fairly bright around horizon. "What an amazing sight! At least 10 arcmin across, it is a large, round ghostly glow of light. There are several small stars enveloped in the nebulosity. A unique and charming object."

1997 October 09

11x80: 1997-10-09, 02:30, Jonkershoek, seeing 3, transparency 3, darkness 5-6 "Ill-viewed, since the portion of sky was setting, in the light-pollution glow of Stellenbosch, behind the mountain. The nebula showed as a delicate smudge, round in shape. The nebulosity is unaffected by stars, and appears even; the 6-inch shows several small stars involved. The nebula was readily seen, even on a bright ligh-polluted background. Just to the north of the nebula lies an 8th mag star, which is the start of a 4-star trail, ending in a 7th mag star to the west; these stars are useful for estimating the size of the nebula; with averted vision, I see it as about 17' across."

1997 November 3

1997 November 3/4, Jonkershoek. 11x80 tripod-mounted, seeing 4, transparency 3, darkness 3, lim mag = 6.0 (naked eye, pole) "Remarkable! A bright glow, some 20' across. Small star nearby on the north-western edge, another on the south-western edge. Had a look, also, at M33, and saw it as a bright, round glow; just like a larger version of NGC 7293 - a formless nebulous glow."

Kerneels Mulder

2008 October 25

Date and Time: 25 October 2008, 20:30
Location: Prince Albert (Western Cape, South Africa).
Instrument: Orion XT10 10" f/4.7 Dobsonian Reflector
Eyepieces: 10mm (120x, 26′ FOV), 25mm (48x, 1° FOV)
Sky Conditions: Clear. Seeing: 7/10. Transparency: Good

At 48x: O-III filter used: Very distinct with O-III filter. The nebula appears circular in form with very slight elongation at the western and eastern edges and is around 15′ in size. The nebulosity is slightly dimmer towards centre and brightens towards the edge. The edge is diffuse. With averted vision three faint stars can be seen within the western edge of the nebula.

At 96x: The three faint stars visible within nebulosity becomes more distinct and easier to see.

Magda Streicher

(no date)

Location: Campsite (South 23 16 East 29 26).

Sky conditions: Clear, steadiness good.

Instrument: Meade 8 inch, Super wide-angle, 18mm eyepiece; 36.2' fov

DSO Report N

Extremely large, very faint, roundish gracious disk. Darker to the inside with some stars, a bright one just off center to the south. Nebula shades out brighter, with a fading north west side. Very low surface brightness. I estimate this nebula about 20 arc minutes. At last the Helix, what a pleasure!

(no date)

16-inch f/10 SCT (EP: 2-inch 32mm SW 127x 32' fov; 2-inch 14mm UW 290x 17' fov; 2-inch 8.8mm UW 462x 11' fov)

Extremely large, very faint roundish ghostly glow known as the Helix nebula. Extremely low surface brightness but could detect the slightly darker area towards the middle section. With (462x) a few stars can be seen embedded, the central star, and on the outskirts of the nebula. The eastern and western periphery of the Helix is relatively well defined. An outstanding close visual double star rounded off the nebula beautifully to the south. The northwestern side is slightly faded out, as the southeastern side which appears lighter with a 9.9 magnitude star in the extreme edge. Very close and just to the west of this star a 16th magnitude galaxy is position at (RA: 22h29m16s en DEC: –20°44'). Search my heart out for this faint little galaxy but with no reveal (462x).

Richard Ford

2016, July, 3rd

Location:Perdeberg.

Time:12:10am.

Sky Conditions:The fainter parts of the Milky Way are barely visible.Haziness only visible on the horizon.Atmosphere stable with little interference.

Instrument:12-inch Dobsonian.

This very large planetary nebula has a very low surface brightness and that this nebula's shape is clearly seen with the aid of an OIII filter where it has the shape of an embroiled coil at both 57x and 75x all over this nebula. To me this diffuse nebula looks like an Helix. This planetary nebula measures 19.5'x 15'.Chart No:33,NSOG Vol.1.

2009 August 15th Saturday

Location:Perdeberg.

Instrument:12"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.

Limiting Magnitude:4.9.

First Impression:Planetary Nebula.

Location:Aquarius.

Time:9:45pm.

Chart Number:No.13(Extract taken out of "Atlas of the Night Sky").

Brightness:Faint.

Brightness Profile:Low Surface Brightness.

Challenge Rating:Easy to observe in dark skies with an aperture of 12-16"inch telescopes.

Overall Shape:Oval and well defined.

Is a disk seen? Yes,a large disk is seen.The Helix Nebula is seen as a large oval embroiled like disk which resembles a helix.By making use of my OIII filter threaded onto my 20mm ultra wide angle eyepiece,the light of this large helix like structure of this large planetary nebula is spread over a large area at 75*.Through the OIII filter the helix like structure of this large planetary nebula is seen.

Is the edge sharply defined? No.

Is there a central star? No.

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