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NGC 598 (1,161 of 18,816)


oc gc pln bn dn gx gxcl ast aka lost




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Triangulum Pinwheel

NGC 598, LEDA 5818, MCG+05-04-069, UGC 1117, Triangulum Galaxy, Messier 33, Triangulum Pinwheel, V 17, h 131, GC 352

RA: 01h 33m 51.02s
Dec: +30° 39′ 36.7″

Con: Triangulum
Ch: MSA:146, U2:91, SA:4


(reference key)

Type: galaxy, Sc

Mag: B=6.26, V=?

Size: 66.06′ x 39.81′
PA: 23°

Image gallery

Sketches  (1)

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Photos  (3)

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Historical observations

William Herschel (c.1784)

Synonyms: H V-017

Observed on the night of 11 September 1784 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it a "milky nebulosity not less than half a degree broad, perhaps 3/4 degree long, but not determined." He later described it as a "faint, extended milky Ray of about 17' in length and 12' in breadth. It is brightest and broadest in the middle, and the ends lose themselves. It has a small, round, very faint nebula just north of it; and also, in another place, a spot, brighter than the rest, almost detached enough to form a different nebula, but probably belonging to the great one. The Ray precedes Alpha Trianguli 18.8' in time, and is 55' more north. Another observation of the same, in a fine evening, mentiones its extending much further towards the south, and that the breadth of it probably is not less than half a degree; but being shaded away by imperceptible gradations, it is difficult exactly to assign its limits." In the Philosophical Transactions, 1818, William Herschel wrote: "1799, 10 feet finder, it is visible as a faint nebula. 1783, 1794, 7 feet telescope, with 75 power it has a nebulous appearance; it will not bear 278 power and 460, but with 120 power it seems to be composed of stars. 1799, 1810, 10 feet telescope, the brightest part is resolvable, some of the stars are visible. 1805, 1810, large 10 feet telescope, the condensation of the stars is very gradual towards the middle; but the the four powers 71, 108, 171 and 220, some nebulosity remains. the stars of the cluster are the smallest points imaginable. The diameter is nearly 18 minutes."

Birr Castle/Lord Rosse

Observations with the 72-inch f/8.8 speculum telescope at Birr Castle noted "Sept 13, 1850. Large spiral full of knots; to nf is a small nebula [NGC 603?], bright, which on a very good night might appear attached to spiral, than which it is brighter. Oct 11, 1850. Spiral arrangement not clearly seen. Nov 27, 1850. Arms of spiral clearly see; fog. Nov 30, 1850. Spiral form very indistinct; wind very high from south. Oct 22, 1851. Viewed for drawing, I should not have seen the spiral arrangement had I not observed it before. Oct 25, 1851. Nebulosity extends for several minutes all round, perhaps for half a degree in radius. Oct 29, 1851. Observed for drawing. Dec 14, 1851. Sketched. Dec. 26, 1851. Drawn. Dec 7, 1855. This neb. reaches in length through at least a field and a half of finder eyepiece. Mr. Stoney's drawing leaves out a great deal of the nebulosity about the centre, and a star suspected to left of centre of the trapezium of stars, perhaps others also. Nov 15, 1857. There are three stars about the principal nucleus. Dec 7, 1857. Carefully observed, with a view to a new sketch. Dec 18, 1857. Carefully observed, and my sketch proceeded with."

Published comments

Doig, P. (1925)

Doig, P. (1925) Notes on the nebulae and clusters in Webb's 'Celestial Objects for Common Telescopes' (Sixth edition, Vol.ii). Part V. M.N.R.A.S., 36(3), 89.

Burnham's Celestial Handbook

In the "Celestial Handbook" by Robert Burnham, he writes: "In the majority of cases of failure [to find M33], the observer is looking for a much smaller and brighter object, rather than a dim glow comparable in apparent size to the Moon" John Herschel and other great observers have remarked that the key to finding M33 is to use a very low magnification. Includes NGC 604.

Bailey, S.I. (1908)

"nebula; oval, faint, two or three stars involved; spiral?"

Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.

Ancient City Astron.Club (1980)

Listed by the Herschel Club, described as "though the mag states as being an easy object to observe through the telescope, the overall galaxy has a low surface brightness making it harder to observe. Use low power to help bring this galaxy into sight with well adapted eyes, use averted vision also. 6-inch, 43x."

Schmidt, K.-H. et al. (1993)

Schmidt K.-H., Priebe A. & Boller T. (1993) Nearby galaxies. Revised machine-readable version of the catalogue. Astron. Nachr., 314, 371. [1993AN....314..371S]

Other names: "U1117,M33". Inclination: (face-on, in degrees) 56 Total photoelectric blue mag 6.27 Total colour index .55 Logarithm of the angular diameter D25 (arcminutes) 2.85 Blue photographic magnitude 6.21 This galaxy is included in a sample of galaxies with velocity less than 500km/s with respect to the centroid of the Local Group. [Nearby Galaxies. Schmidt K.-H., Priebe A., Boller T. (Astron. Nachr. 314, 371 (1993))]

Ashbrook, J. (1968)

Astronomical Scrapbook: Spiral structure in galaxies. Sky&Telescope, June, 366.

Sulentic & Tifft (1973)

(Sulentic and Tifft 1973) notes that this is a 7.0 mag galaxy. Their coded description reads S,LGB,SEV KN ARMS.

Sandage, A. (1961) The Hubble Atlas of Galaxies

This galaxy appears on page 36 of "The Hubble Atlas of Galaxies" by Allan Sandage (1961, Washington, DC).

Clark, R.N. (1990)

See also "Visual Astronomy of the Deep Sky" by Roger N. Clark (1990, Sky Publishing Corporation) page 77.

Gordon, K.J. (1969)

A thorough review is given by Gordon K J (1969) "History of our understanding of a Spiral Galaxy: Messier 33" Q.Jl.R.astr.Soc (1969) vol 10, 293-307. 14.15.6

Anon (1986)

Showing NGC,IC and anon objects in M33, see Sky&Tel. 10/86 p424

Anon (1981)

?...,... (1981) Viewing the Triangulum Galaxy [M33]. Sky&Telescope, Dec, 623.

Corder, J.A. (1986)

Corder, J.A. (1986) Observer's Page: Messier 33 - An amateurs galaxy. Sky&Telescope, Oct, 422.

[amastro] M33 atlas?

It certainly is nice to see the "Atlas of the Andromeda Galaxy" on the NED site! Does the same sort of resource exists for M33 either in print or on the web?


Visit my website at: http://www.dakotacom.net/~jaleblan/index.html


There is an atlas of sorts in the Observing handbook and catalogue of deep sky objects on page 327 by Christian Luginbuhl and Brian Skiff.

The original articles can be found in the ApJ sup series 44 p319 1980 and ApJ 191 p63 1974

I hope this helps

Clear skies

Andrew Murrell


I agree with Andrew that the best "atlas" of M33 is the Humphreys and Sandage paper in 1980 ApJ Suppl 44, 319. Looking just now at the ADS, it appears that that volume is scanned in, so you can have a look at it there.

A long time ago, when the Andromeda atlas was published, Art Hoag said that he took another set of plates with the Kitt Peak 3.8-m so that Hodge could do something similar for M33, but it never came about.



I came up against this problem earlier this fall, and first turned to Christian Luginbuhl and Brian Skiff handbook (Thanks Brian!), an old issue of Deep Sky, an old issue of S&T, and finally the ApJ on the web. Between all of these I was able to observe most of the brighter H II regions. Guess I was lucky, about 10 years ago I found a copy of the Hodge M31 Atlas in a used book store for $3.50! -Jay-

Visit my website at: http://www.dakotacom.net/~jaleblan/index.html


Modern observations

[amastro] M33's Globular Clusters

Has anyone successfully visually observed any of M33's globular clusters? With M31 having so many globulars visible in amateur scopes (Jim Failes and Gary Seronik even spotted G1 with Gary's 6-inch) one would expect that some of M33's globulars should be amateur targets, but I've never seen any mentioned in an observing article. MSA plots two globulars in M33, labelled C39 and U49, but a much more detailed chart would be required to identify them.

[The reason that I'm looking at M33 on a chart at this season is that I'm planning another crack at a Messier Marathon this weekend and I expect that M33 will be so low that the HII region NGC 604 may be the only detectable part of the galaxy. So I was preparing a starhopping chart to NGC 604, using MSA. Clouds caused problems on all three of my previous marathon attempts this year -- I'd sure like to get a cloudfree crack at the 106, possibly 107 Messiers visible from latitude 49. (M74 and M77 are long gone for the year while M30 still is not observable from this far north. There may be a snowball's chance with M55 by this weekend -- I may have seen a hint of a glow touching a ridge in twilight last Sunday morning, but didn't count it. This Sunday M55 is on the horizon as astronomical twilight begins and climbs to an altitude of 2.2 degrees by twenty minutes into twilight!]


Alan Whitman


As I recall from a thread from several months ago, Alan Goldstein found out from Paul Hodge that an M33 atlas similar to the Hodge Andromeda atlas was in the works, and that maybe parts of it were available via a Web site in Seattle. The only survey I know of is by Christian and Schommer (1988 AJ 95,704 --- freely obtainable from the ADS), but this does not have coordinates and the charts are not really suitable....poking around some more shows that the Christian & Schommer paper I'm remembering is 1982 ApJ Suppl 49,405, which has the main survey and charts and coords. You will want the first-mentioned paper also, since it has the BVI photometry.

I found all this, by the way, by doing a keyword search in NED, which has abstracts, and links to the ADS and to its own "Level 5" cyclopaedia.

The brightest clusters in M33 are more likely to be young, luminous open clusters rather than globulars. Remember that the typical globular has an absolute magnitude of about -7.5, which is the brightness of a _single_ F supergiant in an open cluster. Despite having all those stars, globulars are wimps in terms of constituent stars.

I think we also had a discussion last autumn about the globular in the WLM galaxy, which is easy to find albeit faint.

Another "astrophysical" item: note that M33 is barely half a magnitude more luminous than the LMC, and as a consequence has only a handful of globulars (all those rich objects that look like globulars in the LMC aren't).

Finally, another reminder that the Hodge M31 atlas, which marks all the several hundred open and globular clusters, is scanned in at the NED "Level 5" site: http://nedwww.ipac.caltech.edu/level5/ANDROMEDA_Atlas/frames.html



I have also logged a number of M31 globulars (down to about 17.2 mag.) with Gregg Eubanks 30" scope at the Twin Lakes Star Party. I used my own photo chart that was in "Deep Sky" and more recently in "Betelgeuse." I have the info on M33 globulars, and have a few plotted on a photo, but haven't availed myself the opportunity to look for them. Maybe this autumn...

I have also plotted several of the brightest blue luminous variable stars in M31 that I want to look for this fall. They are in the 15 - 16th mag. range. Anyone observed them?

Clear skies,

Alan Goldstein


I have logged vaguely a dozen globulars in the main part of M31 (no typo -- not M33) -- much closer to the nucleus than G1 -- but could do so only by virtue of a well-marked finder photograph which _Sky_and_Tel_ published once upon a time, I have forgotten when. (The globular clusters were given Hubble-Bade numbers, if I recall correctly...). I would love to do globular hunts in other galaxies, but I think I need a well-marked finder image, in the visible, just to find the silly things. So if anyone has such an image I would be happy to try to chase globulars in M33 and perhaps other nearby galaxies.

BTW, M31 G1 was easy in my Intes 6-inch Maksutov a few years ago when I looked at it -- I showed it to several people at Fremont Peak.

-- Jay Freeman (the other Jay)


Some of the globulars in the Hodge atlas are missclassfied. For example the "globulars" G 85, G 137, G 270, G 324 and G 253 are H II regions. The object G 145 is a Seyfert- galaxy, G 99 is a galaxy, too. G 100, G 289, G 325 are stars.

best regards, Jens


At 12:42 PM 04/06/2000 -0400, Alan Whitman wrote:

]Has anyone successfully visually observed any of M33's globular clusters?

]With M31 having so many globulars visible in amateur scopes (Jim Failes and

]Gary Seronik even spotted G1 with Gary's 6-inch) one would expect that some

]of M33's globulars should be amateur targets, but I've never seen any

]mentioned in an observing article.

Check my website for an article on the Globulars of M33 by Rich Jakiel, which I believe originally appeared in the Webb Society Journal: http://redshift.home.pipeline.com/gcm33.htm

As Steve mentioned, we were successful in observing the brightest globular. It's pretty easy to locate in a triangular asterism SE of the main galaxy, but hard to distinguish from several nearby field stars. Check my website for a photographic finder chart: http://redshift.home.pipeline.com/c39.htm

Jim Shields



I think Rich's article on observing globular clusters in M33 was first published in the Webb QJ in April 1997 That would be number 108. I think the piece on the web page is pretty close to what that was.


Jim Shields and I had a difficult time with C39 with my 17.5-inch from a dark site in the Sierras a few years back even with a photographic finder chart and a Guide Star Catalogue chart in hand - and this is possibly the brightest cluster in M33! It appeared as an extremely faint star requiring averted vision and was only visible between 1/3 to 1/2 of the time with concentration. Another mag 16.5 star was sometimes visible 1' SE (confusing the observation). This cluster is located 22' SE of the center of M33 and just 1.2' SE of a mag 11.5 star (on a line between the star and a prominent mag 10.5 pair at 30" separation 4' SE). The position for C39 is 01 34 49.2 +30 21 51.

The journal resource I used was Christian and Schommer's "The Cluster System of M33" from ApJ Suppl, 49, 405-424, 1982. In a follow-up article "BVI Photometry of Star Clusters in M33" in AJ, 95, 704-719, 1988", they found V = 15.91 and B = 16.47, but B-V = 0.56 was slightly too blue (cut off of 0.6) to qualify as a globular. So, C39 may be a massive intermediate-age open cluster (borderline according to their criteria).

U49 has a position of 01 33 45.0 +30 47 47. The AJ, 95 article lists V = 16.24 and B = 16.93, and this is the brightest globular meeting Christian and Shommer's criteria of B-V > 0.60. We were too exhausted from trying to confirm C39 to give U49 a try. Should be visible in a 16-inch or so aperture, though.

Steve Gottlieb


Gramer, Lew (IAAC)

Observer: Lew Gramer; Your skills: Intermediate; Date and UT of Observation: 1997-07-4/5, 05:10 UT; Location: Savoy, MA, USA (42N, elev 700m); Site classification: rural; Limiting magnitude: 7.2 (zenith), intermittent cumulus; Seeing: 5 of 10 - mediocre, intermittent cumulus; Moon up: no; Instrument: 5" f/5 Jaegers refractor on altaz mount; Magnification: 25x; Filters used: None, UHC; Object: M 33 (Triangulum Pinwheel Galaxy); Category: Spiral galaxy; Constellation: Tri; Data: mag 5.7 size 70'x40'; RA/DE: 01h34m +30o40m

Description: Easily found sweeping W of alpha Tri. M33 fills the center of the 2o field of view very nicely, even showing a clear enough outline to render its inclined disc-shape visible (with some imagination). Several tiny fuzzies revealed the locations of unquestionable HII regions in the galaxy - easily confirmed by "blinking" them with a UHC filter. [These might variously have been ANY of M33's named nebulae, including ngc588, ngc592, ngc595, or ngc604 - or even the fainter ic135, ic138, ic142, or ic143! Just a painful reminder to always note both number and POSITION when observing possible sub- objects in M33, M31, M101, or similar large objects!] In addition, an indescribable myriad of stellarings were occasionally noted in the disk, although it seemed impossible with such a low power to readily distinguish mere stars involved in the foreground from the true smaller HII regions. Neither the unfiltered view nor the UHC would reveal any direct hints of M33's spiral arm structure, in spite of the fact that the entire face of the disk was a mass of mottlings and brightenings. M33 was QUITE A SIGHT sitting in the midst of an almost-black wide field! Maybe worth a look later on this year, with a labelled photograph in hand, (such as the one in the Luginbuhl&Skiff _OH_) just to be able to say what true features can actually be visible at such a low power in such a small scope! NOTE: Another nice image of M33, with all its brighest HII regions and/or star clouds labelled, can be found on the Web at: http://www.ezinfo.ethz.ch/astro/atlas/tri/m33.html

Walter Scott Houston

Houston says the galaxy has a magnitude of about 7.0-7.5. He quotes Burnham as saying that people fail to see the galaxy because they tend to search for it with too high a magnification. Visually it covers half a degree, and photographs show detail almost over a full degree. It is important to remember that when searching for such a low surface-brightness object, the object is more easily seen if it presents a noticeable contrast with the background sky. To achieve this, use a low power, wide-field eyepiece. High-power binoculars (20x70) are also well suited. Another factor influencing the observer's chances of seeing the galaxy for the first time, is their expectations regarding the size of the object: whilst not very bright, it is as large as the Full Moon.

Tom Lorenzin

Tom Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "5.7M; 60'x 40' extent; 14M star 40" NE of stellar nucleus; P-filter and low-x show knots of unresolved star clouds and H-II regions in spiral arms - many of which have NGC and IC designations (see Jeff Corder's map on P.424, S&T, Oct.'86); easiest is faint, small N604 (11.5M; <1' diameter) H-II region 10' NE of nucleus; M-33 shares the name "PINWHEEL GALAXY" with M-99 and M-101; good binocular object; good supernova prospect; photo at HAG-36."

Contemporary observations

Auke Slotegraaf

2010 Aug 07/08, Sat/Sun

Karoo Star Party, Britstown, Northern Cape, ZA.

SQM-L 21.7

15x70 Celestron binoculars.

Easy to see, a binocular gem; a very large, irregularly-round patch, looking not unlike the SMC with the naked eye.


If you imagine you are looking for a faint and extended nebula rather than a spiral galaxy, it can be found easily with hand-held 11x80 binoculars in moderately light-polluted skies.


A 10-inch f/5 at 30x, under suburban skies, shows M33 (at low altitude) as a very large but extremely low-surface brighteness globular cluster, straddling the edge of a triangle made up of 9th mag stars, which are shown on the Uranometria chart as lying inside the galaxy. This bright, round globular-like feature lies in the position of NGC 595 & NGC 592 on the Uranometria chart. Whilst the 10-inch shows it as an 1/8 degree area of sky affected by nebulosity, 11x80 binoculars show it larger, at about 1/4 degree, requiring more attention to see, however.

1994 February 21

1994-02-21, 02:45, 11x80 hand-held, Die Boord. Repeatedly saw this galaxy as an elongated faint challenging glow. Dark-adaption for only 10 minutes. Easiest star-hop is from Beta And. Have seen it before from this home-site, and before that from the darker skies of Jonkershoek

1997 October 09

11x80: 1997-10-09, 02:00, Jonkershoek, seeing 3, transparency 3, darkness 3 "Clipped the binocs off the stand and looked to the north, where the conditions were worse; local transparency 6, darkness 7-8. M33 was higher than M31. The Triangulum Spiral was easy, lying to one side in a rectangle of stars. It is surprisingly large, about twice the diameter of the nucleus of M31. It looks like a large a-nucleat globular, with faded edges. It reminded me of the Helix, as I viewed it at low power with the 6-inch; a fine round puff of nebulosity."

2008 December 22

Mount Ceder

16x70 Fujinons

Conditions: Clear, dark.

M33 looks like it could be a naked-eye object (but isn't). Yet the view through binoculars is incredible it looks a bit like Omega Centauri!

Richard Ford

2009 January 25, 21:12 SAST


12-inch f5 (EP: 26mm SW, 20mm UW, 7mm UW)

Conditions: The most clear sky possible. Dark moon and stars magnitude 6 and fainter are visible with the naked eye. Excellent clean sky, limited star flickering and brilliant objects. Limiting Magnitude: 6.2.

Spiral Galaxy located in Triangulum. Faint, well-dfined shape with slight spiral structure. Difficult to observe in light polluted skies, dark skies requirement. Oval and barred spiral, diffuse arms difficult to observe. A few 2nd or 3rd magnitude stars near. No darker regions or areas of uneven brightness observed in the galaxy, but towards the central bulge areas of even brightness are noticeable.

Tom Bryant

2008-11-28 21:00:00

Observing site: Pinnacles overlook

Telescope: C-8

[1h 33m 54s, 30 39m 0s] The spiral arms of this galaxy were glimpsed for the first time.

2006-10-13 23:00:00

Observing site: Pinnacles overlook

Telescope: C-8

[1h 33m 54s, 30 39m 0s] A face on Sc. An obvious large smudge in triangulum. Glimpsed with averted vision, naked eye. 7 x 50 Fujinons

Carol Botha

2008- 12- 01

Location: Oestervanger, Robertson

Time: 22:15

Telescope:8" Dobsonian f5. Eyepiece 15mm. FOV- 45'

Sky conditions:Seeing 4/5

Apparent size: 30' x 30'

Actual dimensions: 62' x 62'(Cartes du Ciel)

Object description:

Spiral galaxy in Triangulum

Diffuse cloudiness, with AV ever so slightly brighter to the centre.

With higher magnification the cloud was less pronounced.

Seeing no spiral structure. The form and size appears to be that of a face-on galaxy

Difficult getting used to the night sounds. "M" has just identified the noise as belonging to a very large frog.

OK, The cloud is framed by a triangle of 3 very bright stars. The bright star to the E has three fainter companions. In the N half I can make out a line of three very faint stars. (In my sketch an arrow points to these.

This was my first glimpse of this galaxy. Very excited to find a new object.

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