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RA: 04h 14m 15.76s
Dec: −12° 44′ 22″
Ch: MSA:306, U2:268, SA:11
Type: planetary nebula
Mag: B=11.6, V=10.553
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Modern catalogues give it a magnitude of 9.6 with a 18 arcsecond diameter. The Vorontsov-Velyaminov description classifies it as exhibiting ring structure. The central star is of magnitude 11.6.
Synonyms: H IV-026
William Herschel discovered it on February 1, 1785 with his newly completed 18.7-inch f/13 speculum telescope. He called it "a very bright, planetary nebula, about half a minute in diameter, but the edges are not very well defined. It is perfectly round, or perhaps a very little elliptical, and all over of an uniform brightness: with higher powers it becomes proportionally magnified." and also as "vB, perfectly round or very little elliptical. Planetary but ill defined disk. Second observation, resolvable on the borders, and is probably a very compressed cluster of stars at an immense distance."
It was also observed by John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "Bright; small; round; first pretty suddenly, then very gradually brighter in the middle; 20 arcsec across. A mottled disc, but so hazy at the borders that I have no doubt of its being a very distant and highly compressed globular cluster. It is not a planetary nebula, though a near approach to one: does not bear magnifying. A power of 320 is of no use. A very remarkable and interesting object."
Lassell, W. (1854) Observations of the nebula of Orion, made at Valletta, with the twenty-foot equatorial. Memoirs R.A.S., 23, 53-62.
Sketched and described.
It is described in the NGC as "planetary nebula, very bright, small, round, pretty suddenly then very suddenly brighter in the middle, resolvable."
In the 5th edition of Webb's Celestial Objects for Common Telescopes it is described as "planetary, bright and round, with low powers of 3.7-inch, but not bearing magnifying. Lassell has described it as the most interesting and extraordinary object of the kind he had ever seen; an 11th mag star standing in the centre of a circular nebula, itself placed centrally upon a larger and fainter circle of hazy light. D'Arrest did not see this, but thought nucleus excentric, edges resolvable, and colour light blue, as E. of Rosse, who makes nucleus granular. Huggins finds the spectrum though, like that of several other nebulae, deficient at the red end, not gaseous."
Burnham, S. W. () "Measures of planetary nebulae with the 36-inch equatorial of the Lick Observatory", Pub. Lick Obs., vol 2, p159-167. "Besides the central star, there are other fainter stars within the nebula .The most prominent of these is near the northern edge of the circular disc. ... This nebula is H IV.26 It has been drawn by d'Arrest and by Lassell (Memoirs RAS, vols 23 and 36). The 14.5mag star [PA 324° 16.17arcsec] does not seem to have been seen by these observers."
Table IV: Not seen, but poss. a pB, R, neb. spot at 10.0m, -12°47'.
!! vB, pS, R, planetary. B central star surrounded by two slightly irregular rings, the inner one being much the denser. The appearance If gaseous 'shells', rather than rings, is caused by both rings being brighter on their outer edges, especially the inner ring.
Doig, P. (1925) Notes on the nebulae and clusters in Webb's 'Celestial Objects for Common Telescopes' (Sixth edition, Vol.ii). Part I. M.N.R.A.S., 35(5), 159.
The RNGC (Sulentic and Tifft 1973) notes that this is a planetary nebula.
Sanford notes that it is "half an arcminute in diameter and of 9th magnitude, bluish in colour. An 11th magnitude central star is visible in larger instruments."
From: "Neat Southern Planetaries - VII."
NGC 1535 / HD 26847/ VV 19/ Herschel IV 26 / PK206-40.1 (04144-1245) (Eridanus) is the most northern planetary that we will discuss in this series. Positioned in an attractive field, this slightly ovoid planetary is easily visible in a 7.5cm., and as a 'star' even in the telescope finder! Sir William Herschel discovered this object in 1785, and placed in his object Class IV; "Stars with burs [Nebulous disks; bur(r)s is now archaic], with milky chevelure [French for 'hair'], with short rays, remarkable shapes, etc." To find it, I used the red 2.8 magnitude Gamma ( ) Eridani (03580-1330), some 4.0O SWW of the planetary. Simply move 18'min.arc. north and then 4.0O west to find the field. Within the field, using a medium magnification, to the south-east is an 2'min.arc. trapezium of 11.4 to 12.3 magnitude stars. At medium magnification in a 15cm. the oval becomes apparent, estimated to be along about position angle 145O. The image bears reasonable magnification, however, I saw little improvement to any visual features in the Celestron-8. Rev. Thomas Webb, in 'Celestial Objects for Common Telescopes' pg.127 states;
"Planetary bright with low power in 3.7" [9.4cm.] but not bearing magnification. [Lalande] has described it as the most interesting and extraordinary object he has ever seen... D'Arrest...thought [that the] nucleus excentric, edges resolvable, and colour light blue, as Earl of Rosse, who makes the nucleus granular."
I suspected a hint of mottling toward the centre, and an O-III did little to improve this. According to the "Webb Society Deep Sky Observer Handbook: Volume 2 - Planetary and Gaseous Nebulae." pg.58, a 42cm. (16.5") telescope will see;
"Blue irregularity round nebula; 351X star surrounded by dark mottling enclosed by a bright ring in slightly elongated shell."
To quote from the apt description of NGC 1535 in AOST2; "In an effective field of scattered stars this bright pale blue planetary nebula stands out conspicuously." or as Burnham's states "[A]..pale bluish disc..."
The photographic magnitude is stated as 9.6, while the visual magnitude is 10.55 and the 'B' magnitude is 11.6. Visually, it subtends an angle some 21.0"sec.arc. Some sources, like Sky Catalogue 2000.0 claims a size of 18"sec.arc. and 44"sec.arc., while Burnham's states 20"x17"sec.arc. Classed as '4+2c', to me this is a bit confusing - Ring structure, with a smooth disk and traces of ring structure. For a 25cm. or less this doesn't describe the object adequately. I could only assumed this meant a ring with a inner ring-like disk. If the Webb Society's description is correct, a 30cm. or 40cm. should be able to see this inner ring. Figure 3 shows an overexposed image of the nearby 5'min.arc. field. while insert shows the telescopic image using a 30cm.
The white dwarf PNN (HD 26847) is an O5 star of magnitude 12.1, but it is invisible for telescopes below 25cm. I am certain the star is particularly difficult to see in poor seeing because it merges into the planetary's nebulosity. Californian Jack Marling in an article in June's 1986 S&T (pg, 633) claims in a 50cm. (17.5"); "The 12th magnitude star is easy to see." David Frew also claims to have easily seen the PNN using a direct-vision prism, that reveals a stellar 'streak' within the planetary. I attempted this with a C8, and admit I could not see it, though others might have some better luck. Spectrally the white dwarf is stated as '?npe' - suspected nebulous lines and a peculiar spectra.
Radial Velocities were first measured in 1952, at a small 1.2kms-1. By 1993, the latest measure is about 3.2kms-1. The distance of 2.14 kiloparsecs was first proposed by Cahn and Kaler in 1971. More recent estimates suggest a closer 1.65 kiloparsecs.
A good 'honest to god' planetary!
Photo Index by Jim Lucyk: Sky&Tel. 6/86 p632.
Terzian Y (1980) Q.J. R.astr.Soc vol 21, p82-92 [09.16.1] notes that this planetary shows multiple shell structure.
Hartung writes: "In an effective field of scattered stars this bright pale blue planetary nebula stands out conspicuously; it is about 30 arcsec across and well defined with fairly even light. No central star is visible..."
Houston notes that this 9th mag nebula lies in Eridanus. With a magnification of 100 on a 4-inch refractor, he did not need averted vision to see it.
Houston calls it a "bright planetary nebula .. which swims like a celestial jellyfish. Its 9th mag oval disk is about three-quarters arc minute long and surrounds a 12th mag central star."
Steve Coe, observing with a 13" f/5.6, notes: "Bright, pretty large, round, easy to spot at 100X. Going to 180X shows two concentric rings, one bright near the center, the other ring dimmer and larger that forms the outer edge of this planetary. The central star is easy at high power and the nebula is light blue at all powers."
04 14.3 -12 44 17.5: very bright, fairly small, high surface brightness, mag 12.5 central star visible, blue color. This planetary has a double shell structure with inner shell slightly elongated and a faint rounder outer shell. Small dark gaps are visible around the central star.
13: at 360x the central star visible surrounded by two shells; a bright annular inner shell and a fainter outer halo.
8: bright, greenish, fairly small, round.
Listed by the Herschel Club, described as "small, circular, almost stellar, definite blue tint noticed. 6-inch, 40x."
Mullaney writes: "This is a small pale blue-green planetary in Eridanus .. shining at about 9th mag and measuring 44 arcseconds by 18 arcseconds, NGC 1535 has a faint central star and disk structure that can be glimpsed in an 8-inch or larger telescope."
Observer: Chuck Layton Your skills: Intermediate (some years) Date/time of observation: 1 Feb 98 0330 UT Location of site: Roy, WA (Lat 47 N, Elev 200ft) Site classification: Suburban Sky darkness: 6 1-10 Scale (10 best) Seeing: 8 1-10 Scale (10 best) Moon presence: Minor - crescent or far from object Instrument: 8" f/6 Newtonian Eq. Magnification: 38X, 177X Filter(s): none Object(s): NGC 1535 Category: Planetary nebula Class: 4 + 2c Constellation: Eri Data: mag 9.4 size 20" x 17" Position: RA 04:14 DEC -12:44 Description:
Another relatively easy to locate planetary neb. Large enough at low power to differentiate from nearby stars. At high power the central star is hard to serperate from the small angular bight portion of nebulosity. Surrounding this central section was a "seperate", dimmer oval of gas, uniform in bightness, with a slight extention to the SW. This gave the appearance of a small bright nebula floating on top of a larger dimmer one. Interesting to observe.
Shortly after this observation the clouds closed in again. Living in the Pacific NW sure makes you appreciate ANY clear night sky!!!
Marling, J.B. (1986) In pursuit of planetaries. Sky&Telescope, Jun, 631.
Observer: Jeff Medkeff; Your skills: Advanced (many years); Date/time of observation: Oct 4, 1997; Location of site: Rockland Observatory, Sierra Vista, Arizona (Lat +31.5, Elev 4550 ft.); Site classification: Rural; Sky darkness: 6 Limiting magnitude; Seeing: 6 1-10 Seeing Scale (10 best); Moon presence: None - moon not in sky; Instrument: 4.5" f/7 Dob; Magnification: 32 53 68; Object(s): NGC 1535
NGC 1535 pn in Eridanus. Small. Very bright, takes magnification well. No hint of annular appearance. [I later learned that this pn is often called the "Strawberry Nebula", allegedly because of its strong red color. Subsequent observations do not show color with the 4.5".]
William P. Clarke (San Diego, California, USA) writes in The Webb Society Nebulae and Clusters Section Report No. 10, July 1992: "A small round ghostly patch with a central star and blurred outer edge (21-inch f/20, x140)." In Report No. 11, January 1993, he writes: "The bright inner disc is easily visible and is about 20 arcseconds in diameter. The outer disc is hazy and gradually fades away; it is about twice the diameter of the inner disc. This shell structure is very much like that of NGC 2392. Contrast greatly improved with an OIII filter. (21-inch, x350)"
Observer: Lew Gramer; Your skills: Intermediate (some years); Date/time of observation: 9/10 Feb 1999 04:00 UT; Location of site: MIT Haystack Obs., Westford, MA, USA (Lat 43N, Elev 30m); Site classification: Exurban; Sky darkness: 6.6 Limiting magnitude; Seeing: 4 1-10 Seeing Scale (10 best); Moon presence: None - moon not in sky; Instrument: 17.5" f/4.5 dob reflector; Magnification: 55x, 225x; Filter(s): None, OIII; Object(s): NGC 1535
Description: After Steve Clougherty & I finished setting up the ATMs of Boston 17.5" Club scope, we had to wait out a brief threat of cloud-over. As bands of cirrus and cirrocumulus obligingly dissolved or swept off to the S, we began this evening's observing in earnest. First target was the bright n1535 in Eri, easily found by sweeping ENE of gamma Eri just about exactly 4o, stopping just a wide field E of a beautiful equilateral trio of mag 9 late spectral-type stars.
At lowest power n1535 was distinctly non-stellar, with a yellowish coloring. Jumping immediately to 9mm (225x), the bright, seemingly smooth face of the nebula became more yellow-green, with a fairly obvious irregularity to the N, either the edge of a lobe of nebu- losity or perhaps a dark obstruction. Also, the face showed a non- symmetric flattening on the W, probably indicating more structure. The central star was neither strikingly obvious nor very difficult once looked for. Surprisingly, even without any filter there was a hint of a faint outer halo, or at least of much fainter nebulosity surrounding the central disk. This "second tier" of the nebula (if it was not in fact the actual halo) was only subtle, and was best seen to the ESE of the center. Finally, with the idea of enhancing this outer haze, we blinked the view at 225x with an OIII filter. Strangely, the central star was neither more nor less visible than it had been. But suddenly, the annular (ring-like) nature of n1535 became apparent, with just the suggestion of irregularities in the inner darkened area to averted vision. As expected, the outer halo could be clearly seen to SE, but now actually showed up as brighter and more elongated W of the disc, reaching out to perhaps twice the radius of the bright inner disk, roughly per cataloged sizes.
Last night (11-10-99) I viewed NGC1535 with a 16", and was taking time to compare it with various photos and images (DSS, Doug Snyder's, Vickers). Not terribly impressive in the 16" and none of the images available made me salavate. However, I was feeling energetic, so I cranked up the 36" (suffering from truss sag...and therefor collimation) and used a 12mm Nagler.(that's 390X for those who can count). The following are excerps from my notes, partially readible between slobber spots:
"HOLY COW! WOW! WHAT'S THIS? GOOD GRIEF! IS THIS THE SAME OBJECT? WOW..........X33"
I'm not sure at what aperture the transition takes place at, but NGC1535 takes on a whole different view in a 36".......the central star is bright and has a bluish tinge to it, with an inner circle distincly dark grey and with a very distinct circlular boundry. An outer shell surrounds the inner and presents a hint of copper copper. This, too, has its own boundry, but is subtley more diffuse and lighter than the inner shell. All the images that I had available to me, paled in comparison to the visual image. Obviously not true with most objects, but true in this case with what was available.
I would be interested in hearing from any members of the group that have instruments in the 20" - 30" size, as to their visual views relative to prints or digital images. I would guess that NGC1535 becomes a different animal somewhere in that aperture range. Neal
I just revisited this object, this time with my 25" f/5. The view in my 16" previously was good, but the 25" at 300x really displayed this object as quite knotty, with a very bright, blue central star. I selected it to view at the recent Virginia Association of Astronomical Societies meeting this past Saturday. Unfortunately I didn't get too much chance to study it as there was always a long line. A stunning planetary nebula, as is N1501 in Camelopardalis. To see is N1501 in a 25" at 1,000x is awesome. Planetaries are often forgiving of less-than-ideal seeing conditions. Put lots of power to them and enjoy. Kent Blackwell
Tom Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "9M; 20" diameter; 11.5M center star; distinct bluish discus!."
= PK206-40 1 = HD 26847 = BD-13 842
PK: three *s 2'.5 W.
6cm - vis as m9 * 20' E of equilateral triangle of *s on AE.
7cm - just discernable from a * @ 30x. 75x: circ spot that seems to have sharp center w/averted vis. no other details, too sm! BS, 26Nov1992, Anderson Mesa.
15cm - fairly br well-def ellipse w/distinctly *-like point at center. 20" long. good object. HM/BS, 15Oct1971, FtL.
- evenly br inner circle and incompl narrower outer shell. cen * perhaps. greenish. HM.
25cm - br & vlg. 180x: cen * seen. br well-def core 20" across w/fntr halo 35" across. creamy blue.
30cm - neat! elong pa10, 25"x18". has two distinct zones @ 220x: 12"x8" inner zone around sparkling cen *; br fuzzy halo fades pretty abruptly at its outer edge. 440x: inner `core' has definite br edge, and sfc of core is mottled w/holes. three m13.5-14.2 *s 1' W. one of the neater pn's. CBL.
[amastro] posting, Sat Nov 25, 2006
82" telescope, McDonald Observatory near Fort Davis, Texas, USA
f/13.7, 35mm Televue Panoptic (5' fov, 812x)
Bright dual-shelled PNe, both shells aqua in color. The bright inner shell has a ropey, intricate outer edge, while the dimmer outer shell is featureless and has a nice sharp outer edge. Bright central star. Very dramatic at this aperture.
12-inch f/10 SCT (EP: 2-inch 32mm SW 95x 42' fov; 2-inch 14mm UW 218x 23' fov)
Small, bright and well defined round planetary nebula with a definite blue hue and sharp edges. The northern portion is well defined where as the southern side appears fuzzy. With higher magnification (218x) it appears cloudy at the edges. The central star can be seen with averted vision. This planetary is outstanding against the background stars. The two galaxies NGC 1538 & IC 2048 are situated 27' arc minutes to the south outside the field of view. Discovered by William Herschel in 1785. He stated that it is a remarkable and interesting object.
Location: Pietersburg South 23o 53. East 29o 28.
Sky conditions: Clear.
Date: 4 Julie 1997.
Field of view: 52.7 arc minutes.
ASSA-DSO - Report J
NGC 1535 P/n Mag 10 size 42
Small, bright, well defined, round planetary nebula with a definite blue even colour, and sharp edges. Beautiful object.
Sutherland (Ouberg Quarry)
11x80 tripod mounted binoculars
Conditions: NELM: fainter than 6.0 at the S.pole
Appears stellar in binoculars, like a 9.5mag star.
Observing site: Little Tycho Observatory
[4h 14m 12s, -12° 44' 0"] A pastel blue planetary nebula, looking like an out of focus star in the 24.5. The sky was becoming cloudy, a clear sky might have shown more detail.
Instrument:12-Inch 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.
This planetary nebula is seen as a bluish oval disk at high magnification and is well defined.At low magnification this nebula looks like a fuzzy out of focus star.
It measures 1'*0.3'.
Telescope: 12 Dobsonian f4,9. Eyepiece 15mm. FOV- 36
Sky conditions: Seeing 3/5 (intermittent high cloud cover)
Actual dimensions: 0.7' x 0.7'(Cartes Du Ciel)
Planetary nebula in Eridanus
Very dim disk. Hazy bluish colour. With higher magnification seeing conditions did not reveal a central star .
Arc of dim stars just W of the nebula. Four stars in diamond shape to SW. a line of two bright , two dimmer stars to N. Four stars in kite formation to E
Now that I realize Ive found the eye of Cleopatra I will have to set up a meeting in really dark skies with good seeing.
The Messier objects
The Bennett objects
The Caldwell list
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