Naming Omega Centauri and 47 Tuc

[Stevo69]

Originally Posted by ballaratdragons

There was an article in AS&T (last year I think) about this exact subject.

How objects have too many names. Some have 4 or 5 classifications!!!!
An 'M' number, an 'NGC', an 'IC', an 'MCG' and a common name. Some other objects use differing catalogue numbers and leave out the more common ones ('M', NGC' etc). Then there are PGC's, SAC's, etc.

Then we get to Star catalogues: SAO, TYC2, GCVS, WDS, BossGC, GSC, HD, BD, CD, CPD, HR, Flamsteed, Bayer, and common names!!!!

How is anyone expected to know what is what up there with so many classifications for each object!!!!!

I agree, why couldn't the IC catalogue numbers just continue on from the NGC numbers? Why does a Messier object get an NGC number? Why do people have to complicate things?

A case in point is the Caldwell catalogue. As much as I admire an respect Patrick Moore, why did he have to make a whole new catalogue? Well, I know his reason for it, that's commonly known. All these different catalouges, i feel, just make life more complicated!

hoo roo

Steve

[glenc (Glen)]

I am not a great fan of renaming/renumbering objects (e.g. Caldwell) but I don't mind if they are named after the person who found them or if they are given a name based on their appearance.
Omega Cen was found by Halley in 1677 and 47 Tuc was found by Lacaille in 1751. Maybe we could call them Halley's Great Globular Cluster and Lacaille's Great Globular Cluster. (I use the word great because they both found other globular clusters.)
http://www.seds.org/messier/xtra/history/dis-tab.html

[ngcles]

Hi All,

I very, very much like Glen C's suggestion. It removes any objection I could possibly think of save perhaps one. Halley was also the discoverer of M13 (that other "great" globular) -- he was certainly the first one to place it in a catalogue. When the people see the title, they might be inclined to confuse it with M13. The announcement of Omega Centauri (NGC 5139) is in the same catalogue.

http://seds.lpl.arizona.edu/messier/...halley_pt.html

As for the NGC/IC etc etc, I believe Dryer in compiling the NGC set out with the intention of consolidating all discoveries into one catalogue. He leaned heavily on Herschel's "general catalogue". I think Dryer tried to make one "be-all-and-end-all" master list that would include everything that guys like Messier, Lacaille, Dunlop, Herschel(s) etc etc.

He arranged the NGC basically in RA order starting at 0hrs as it was at his epoch (1900?? -- I'm not certain). Eg NGC 1 is in Pegasus. It is now at 0hrs 7mins due to precession.

Because it is arranged in RA it is impossible to add to without ruining the scheme. Just a few years later when the additions and errors had to be cleared up they then published those in a supplement -- The first IC (also arranged at least mostly in RA order) and then a second supplement as the pace of discovery increased.

The other catalogues came out mainly as a result of survey work becoming deeper and deeper and then finally being all done photographically. There are several more specialised catalogues that list things like "flat galaxies" and then "peculiar galaxies" (Arp) for those who just want to investigate special classes and sub-classes of things. Some very small "catalogues" arise because someone publishes a paper about say two new discoveries. Sometimes mistakes are made and a previously discovered object like the G.C NGC 6717 was included as Palomar 9 in the Palomar list of new G.Cs.

But I do agree with you it can be confusing. There is a convention (at least among professional astronomers) as to how they cite when a paper is published in the ApJs for example. I can't remember off the top of my head how it works but it basically amounts to "cite the most commonly used catalogue first".

It would be great if we had a naming scheme like the biologists use that grouped "like objects" together in a hierarchy, and where the name also conveyed something about the object. But I think it's too late now ...


Les D

[AJames]

No No No No No.... (with operatic overtones)

Halley and Lacaille, although the observers and discoverers of both these objects, the did not really disclose what they were.

1) Edmond said in 1677 that Omega Centauri was just a "luminous spot or patch in Centaurus" - no mention of stars anywhere. It was actually Ptolemy who discovered that the area was the "nebula on the back of the horse" - dorso Equino Nebulous. Halley added virtually nothing to what we know of this object. We could name it Ptolemy's cluster - but that is reserved for M7!

2) As for Lacaille - Abbe to his mates - at least had a telescope when he viewed 47 Tuc in 1751. He named it numero one in his catalogue, but he said;"It resembles the nucleus of a fairly bright small comet" - placing it under nebulolisities not accompanied by any star visible in a telescope of two feet. Lacaille didn't even name it 47 Tuc - Bode did that sometime later.

Halley claim for this "deep-sky discovery" is in my opinion just totally bunkum, with Lacaille's not far behind.

Indeed, it was very probably James Dunlop who first reported both these objects as being a star cluster and stellar in nature - though certainly both were observed using larger telescopes in somewhere between 1751 and 1820.

No! (with titanic and emphatic connotations) The name of the object should fit the description named by southerners for southerners - and not just on some trumped-up discoverer under very dubious circumstances. These deep-sky supremos of their class, size and in the Top 10 of the deep-sky objects.

When you read statements like;

"Messier 13 (M13, NGC 6205), also called the 'Great globular cluster in Hercules', is one of the most prominent and best known globulars of the Northern celestial hemisphere."

[ See http://seds.org/messier/m/m013.html ]

It makes no mention of the larger and brighter southern examples.

...but do in my mind keep coming back to the Rev. T. Webb ;

"The mere aspect of this stupendous aggregation is indeed enough t make the mind shrink with a sense of the insignificance of our little world. Yet the Christian will not forget that, as it has been nobly said, He took of the dust of this Earth, and with it he rules the universe!"

... but had the Rev seen Omega Centauri he would have needed a bottle of whisky, two bullets and a gun; then take a strong sedative just to calm him down!

As for 47 Tuc, it finally took R.T.A. Innes in 1896 to start balancing the ledger against the heavily weighted northern bias. He describes the true nature of 47 Tuc, he called;

"Most glorious globular cluster, stupendous object, completely insulated, stars all 12th to 14th magnitude. Central blaze ruddy, rest white."

If little pip-squeak M13 is a "superb globular", then what are these two southern deep-sky gems that meet their magnificence?

Where not just talking about some little piddling objects here!

[Stevo69]

Originally Posted by ngcles

As for the NGC/IC etc etc, I believe Dryer in compiling the NGC set out with the intention of consolidating all discoveries into one catalogue. He leaned heavily on Herschel's "general catalogue". I think Dryer tried to make one "be-all-and-end-all" master list that would include everything that guys like Messier, Lacaille, Dunlop, Herschel(s) etc etc.

Yes Les, I think Dreyer was trying to do the "right thing". And in most, I think he succeeded. But who started the IC catalogue? why couldn't they continue adding onto the end of the NGC.

I guess everyone who comes along in history believes their catalogue and nomenclature will be the definitive in their time, and presumably into the future. (mmm, I might start my own catalogue!!)

I agree with naming such as Omega Centauri, but I can stare at images of the 'Eagle Nebula' for hours and I still cannot see an eagle! My point is that naming an object by what shape it depicts can be very subjective, from the point of view of the observer. If sombrero hats were not as popular outside the Americas, would we feel as comfortable with the 'alternative' name for M104?

hoo roo, Steve

[glenc (Glen)]

Andrew, they did see them as "deep sky" objects not just stars. Should we require that they resolve them? And thanks Andrew for starting an interesting thread. Les, as you said, M13 is not Halley's greatest globular, it is the 8th brightest glob in the sky.

[Gargoyle_Steve (Steve)]

After looking at Omega Cent through 20x80 bino's several times it reminds me of a wayward golfball, sitting on the dark coloured bottom of the creek. I know it isn't a historical, mythical or even a inspiring name but I sometimes refer to it in the privacy of my own head as the Golfball Cluster - it is the only cluster I've seen through bino's that is both large enough and of sufficient density and distribution of it's stars as to give the impression of being a solid ball when viewed that way.


Glen .. if there is another cluster around with similar attributes I'm sure that you'll know it - feel free to correct me if I'm wrong mate!

[glenc (Glen)]

Steve it does look like a golf ball in 20x80s but I prefer a historical name.
People get credit when they find comets, but not when they find DSO.
Maybe we could call omega Cen Halley's best globular. 47 Tuc is Lacaille's best globular and M83 is Lacaille's (only) galaxy.
Lacaille found a galaxy with a 0.5" refractor, that deserves some credit.

[Argonavis (William)]

Originally Posted by AJames;2524862)

As for Lacaille - Abbe to his mates - at least had a telescope when he viewed 47 Tuc in 1751. He named it numero one in his catalogue, but he said;"[I

It resembles the nucleus of a fairly bright small comet[/I]" - placing it under nebulolisities not accompanied by any star visible in a telescope of two feet. Lacaille didn't even name it 47 Tuc - Bode did that sometime later.

Herschel in 1855 refers to "superb globular cluster, No 47, Toucani of Bode...one of the finest objects of this kind in the heavens."

with this sort of provinence, why would you rename it?

It was listed by Bode in his catalogue of 1801, which is a separate work to his Atlas "Uranographia" of the same year.

There is only one other spectacular southern object that I know of whose designation has survived from Bodes catalogue - 30 Doradus, otherwise known as the Tarantula Nebula.

[glenc (Glen)]

Halleys' Superb Globular (omega Cen) and Lacaille's Superb Globular (47 Tuc)?

[OneOfOne (Trevor)]

I personally have always liked what they call it on my Celestron GoTo menu, Omega Cluster, which could be interpreted as "The Final Cluster", or "The Last Cluster". The name sums it up pretty well being the largest, and greatest.

Don't know about 47Tuc though...still thinking.

[AJames]

Argonavis said - and these are my replies;

"Herschel in 1855 refers to "superb globular cluster, No 47, Toucani of Bode...one of the finest objects of this kind in the heavens." with this sort of provinence, why would you rename it?"
* "provinence". Do you mean providence or prominence? I've presumed the former.

While John Herschel did write this, it was during the time when he was reflecting on his observational endeavours of his father. However, although Herschel didn't give it a name doesn't exclude the possibility of giving them proper names. This issue is necessary because most northerners could care less about objects they can't see. 47 Tuc's declination makes it an unworthy target to about +15 degrees latitude - well away from the traditional population centres of the world - and its is really this reason for the neglect.

"It was listed by Bode in his catalogue of 1801, which is a separate work to his Atlas "Uranographia" of the same year."

Yes, this is true. However, but both were actually intended to be together. The catalogue was a validation of its worth, but he knew the popular part of his work was the atlas which was - along with the newer editions that were to come - his money making and enduring endeavour. Furthermore, the catalogue was a star catalogue and not a deep-sky one. I think it is confusing to label deep-sky objects as stars - even if this is historical the case. Ie. We don't call M22 by its Flamsteed Number do we?

"There is only one other spectacular southern object that I know of whose designation has survived from Bodes catalogue - 30 Doradus, otherwise known as the Tarantula Nebula."

I was very surprised you quoted this as an example, because it actually validates the whole gist of the argument. If 30 Doradus is also known as the Tarantula Nebula, then why aren't 47 Tuc and Omega Centauri given the same treatment - especially if they are significantly brighter and more prominent?

[Note: Another the magnificent northern example is h and chi Persei, two actual open star clusters known as the "Double Cluster of Perseus". chi Persei is listed as the Flamsteed star, 6 Per, even though it is nearly always is referred to as the star cluster, NGC 869. However, fainter h Persei, which is the brightest star of companion cluster NGC 884, has no Flamsteed number.
Actually both clusters are actually officially recognised as the "Chi Persei Cluster" - another example of the frankly bizarre nomenclature / naming system - but the point is - why give star names to objects that are clearly star clusters with many stars or even known nebulae which are so visually different?
Yet, after all this, what do nearly every northerner commonly call this... "Double Cluster of Perseus"! ]

No! I think as southern observers who are impressed with the magnificent bright objects in our southern skies should be OBLIGED to use proper names.

Comment : Let's just say your avatar here of "Argonavis" portrays something useful that is actually relating you. Would you instead prefer your ABN number (Australian Business Number) instead and even just the non-descriptor of "Hey You"? Shouldn't we apply similar precepts to the best deep-sky objects, and say, for arguments sake, also the Top 100 stars in the sky?

I do intend to make an additional statement on bringing proper names into common usage in due time...

[AJames]

Originally Posted by glenc

Halleys' Superb Globular (omega Cen) and Lacaille's Superb Globular (47 Tuc)?

Glenn,

I do at heart agree with this.

However, I do have reservations with "Halley's Superb Globular". It concerns me as a misnomer. This is because it was Bayer who listed it omega centauri in the first place - prior to Halley, while to true discoverer of this "hazy" object was Mr. Ptolemy. [Just because his observations were fraudulently obtained, should we dismiss his contribution? Sadly we cannot CSI-like prove that Mr. Hipparchos was the original observer - as this document is lost to history. Yet you would expect with this Rhodes observers eye to detail, that omega cen was certainly visible.

Both names you suggest here are worthy contenders for the crown...

How about just ;

"Omega the Magnificent" -
Omega le magnifique

Andrew

NOTE: Personally, and without any malice to you, these given names I think still somehow lack the necessary "oomph" that really sets them apart . Though I know that the real use of some other superlative(s) or some (im)proper adjective here is always esoteric at best - and will always be hard to agree on.

[AJames]

I showed a picture of Omega Centauri to one of my mates, who is not actually interested in astronomy, (surely the ultimate oxymoron). He immediately suggested the "Penthouse Cluster." Shocked, at first I thought he was referring to the popular R-rated magazine, and my mind flashed too, well... . However, what he was referring to the creme de la creme of a residential building - which is at the top and closest to the heavens. Huuummmn... I though... Oh for a ziggurat !!!
This got me thinking - "The Ziggurat Cluster"

Definition: From the middle-eastern word of ziqqurratu. A rectangular stepped tower, sometimes surmounted by a temple. Ziggurats are first attested in the late 3rd millennium BC by the Akkadians and probably inspired the biblical story of the Tower of Babel (Gen. 11:1–9).

Reaching up to Heaven indeed! Surely, even Ptolemy would be pleased!

[AJames]

Celestial Urania
Thy wonders we would know -
Those mysteries and marvels which
Alone inspire us so
That nightly from this Earthly sphere
We try to comprehend
Thy Universe as infinite,
And ages without end.

O beautiful Urania,
As thus we look afar,
And night across the awful gulf
Between us and that star
Which we have all found of all thy host
The nearest one to be
How can we then but stand appalled
By thy profundity?

O Heavenly Urania
In numberless array
Thy suns and system scintillate
Throughout the vast display,
The clusters and the nebulae,
The Galaxy and all,
But midst this cosmic throng appears
Our world, remote and small!

Celestial Urania
With thee can nought compare
Thy magnitudes transcend all thought,
Thy view sublimely fair;
O heavenly Urania,
Be ever this our aim:
To love, serve, honour, study thee -
Thy Science to proclaim.

Frederick Charles Leonard
J.RAS.C. October, 1923

[glenc (Glen)]

The question is should we give credit to the first one who saw them as stars, or to the first one who saw them as DSO or to the first one who saw them as globulars?

Dunlop's 1826 descriptions are:
D18 (47 Toucan, Bode.) This is a beautiful large round nebula, about 8' diameter, very gradually condensed to the centre. This beautiful globe of light is easily resolvable into stars of a dusky colour. The compression to the centre is very great, and the stars are considerably scattered south preceding and north following. - Figure 1 is a good representation. 8 observations

D440 Omega Centauri (Bode) is a beautiful large bright round nebula, about 10' or 12' diameter; easily resolvable to the very centre; it is a beautiful globe of stars very gradually and moderately compressed to the centre; the stars are rather scattered preceding and following, and the greatest condensation is rather north of the centre: the stars are of slightly mixed magnitudes, of a white colour. This is the largest bright nebula in the southern hemisphere. 8 observations

[AJames]

Glenn, let me get this right...

You said;
"The question is should we give credit to the first one who saw them as stars, or to the first one who saw them as DSO or to the first one who saw them as globulars?"

Omega Centauri
1. Ptolemy (stars) - then Halley
2. John Dunlop
3. John Herschel

47 Tuc
1. Lacaille
2. John Dunlop
3. John Herschel

Reasoning.
Omega
1. Ptolemy saw this as a "hazy lucid spot"
2. Dunlop first resolved the stars
3. John Herschel first to separated the globulars from the open clusters

47 Tuc
Omega
1. Lacaille saw this as a "hazy lucid spot"
2. Dunlop first resolved the stars
3. John Herschel first to separated the globulars from the open clusters

Andrew

[glenc (Glen)]

I would give credit to the first to see it as a "Deep Sky Object", not just a star.
James Dunlop saw omega as a "beautiful globe of stars". He saw it as a globe and as stars, does that mean globular?

[AJames]

Glen

Yes, Dunlop did describe the stars as a globe, but the term only meant as a cluster of stars not a globular star cluster per se. I.e. All the star clusters were viewed as the same. I think you will find that the word "globular cluster" is a far more modern invention.

According to some, the true "globular" classification was by John Herschel in "Catalogue of Nebulae and Clusters of Stars" the Royal Phil.Trans., 154, 1 (1864). However, others say it was the 3rd Earl William Parsons Rosse around 1845, who began to resolve the cores, and revealed the tens of thousands more stars than any open cluster. Needles to say, the first written term was John Herschel.

The main reason was NOT that globulars looked different from the open clusters, but because they were relatively so rare objects. After Dunlop, 49 were known, and most of them remained either unresolved or poorly examined. This had only increased to 56 in 1840, and even the NGC in 1888 listed only 66.

The "real killer" for globulars came with the first observations of variable stars, which showed that the distances of these objects were away from us - anagalactic distances and not within the nearby arms of the Galaxy like the open clusters.

"Globular Day", if one was ever to be recognised, is the 18th May 1860. This was when Arthur Auwers discovered the nova in globular M80. Peaking at 6.7 magnitude, it remained at this magnitude for three days, only to eventually fading beyond telescope view on the 16 June 1860 around 11th or 12th magnitude. Its intrinsic brightness, if it was indeed associated with the cluster, suggested these objects were perhaps fundamentally quite differ-
ent from the open clusters. Until 2007, the only other galactic globular nova that we have observed was within NGC 6553 (V1148 Sgr) in 1945.

The first of the regular globular variables were casually discovered in 1881, and the first of the important RR Lyrae pulsating variables was by Solon Bailey in 1895. In our far southern skies, the first variables were found in Omega Centauri by Pickering in 1893 and 47 Tucanae by Bailey in 1902.

It was Harlow Shapley between 1916 and 1918 who cemented globulars as separated types, finding the old RR Lyrae variable stars and using them to establish they were many kiloparsec distances. Walter Baade eventually used globulars in 1944, and determined the fundamental distinction between the Population I and II stars within the Milky Way Galaxy. This became the key. The ages of globulars were much older than the typical brighter stars seen in the Galaxy.

This finally killed and severed the old links between globulars and open clusters.

Andrew

[ngcles]

Hi All,

Well, this has all been very interesting and the divergence of opinion on the subject begs the question of whether any consensus can be reached. But even if it can be reached here will any proposed names then reach wide acceptance?

My attitude (for what little it is worth) on the subject is known from the beginning of the thread. But, I am at least cheered by the fact that there seems to be a leaning towards a name(s) that somehow tie in the historical aspect and/or a descriptor that will still be "sensible" in a couple of hundred years.

How will people react in 100 years time to names like the "CBS eye" for NGC 3242 -- more widely known as the "Ghost of Jupiter", or "Cheerio Nebula" for NGC 6337, or the "Pacman nebula" for NGC 281, the "Cheeseburger nebula" for NGC 7026 or ... Yuk, Yuk, YUK! I've been waiting with bated breath (not) for the "Twinkie nebula" and the "Coke nebula"

I'm still happy with Omega Centauri. But I also hear a lot of people call it "Omega CentauRUS" which also makes me **cringe**. I'm also happy with 47 Tucanae at present. But, I happened to already have the glue out and after reading some of the responses above I thought, how about "Chiron's Superb Globular" for NGC 5139 -- which kills the Halley/Ptolemy sticking point and it has just a hint (a bare hint admittedly) of alliteration to it?

And for 47 Tucanae (NGC 104) we need something a little different but with no less "gravity" -- how's about "Stupenda Australis" or simply "La Stupenda"?? Joan Sutherland (not that I'm and Opera fan at all) was known as "La Stupenda" in the opera world. Just a thought. Seems fitting enough. What's the connection between Joan Sutherland and 47 Tucanae? None at all -- Stupenda just kinda fits as a descriptor and it's close sounding enough to superb. but doesn't sound glitzy like "the stupendous cluster/globular". Maybe it's just a "stupider" idea!

Golf Ball? -- please noooooooooooooo!

Re: the novae in globulars, Andrew I think M14 had a nova, but I guess it wasn't "observed" in the strictest sense because it was only discovered 26 year later when someone noticed in on a plate taken by Hogg in 1938.

http://seds.lpl.arizona.edu/messier/m/m014.html


Best,


Les D

Mrs. Schroedinger to Mr. Schroedinger:
"What in the hell did you do to the cat? It looks half dead!"