Open Cluster catalogue question

[stephenb]

I have been researching many DSO lists, NGC/IC catalogue and I have noticed many, if not all open clusters have an attached designation "OCLxxx". I assume this stands for "Open Cluster List" or similar. However I cannot find any information on this particular designation.

Is it an official designation for open clusters or something some individual has created?

Can anyone shed some light on this designation?

[M54]

Could the LXXX be roman numerals?
It's the number 80 if it is.
But I guess this doesn't clarify things any further.:shrug:

[Enchilada]

The origin of the OCL or OClxxx(means Open Cluster [OCl] and NOT "Open Cluster List"), of which there are 1112 in number, comes from; Alter, G., et.al., “Catalogue of Stellar Clusters and Associations”, 2nd Edition, Akademiai Kiada, Budapest, Hungary (1970) (The first was in 1958, with additions.)
The OCL is the number assigned to the clusters to enable a data base of information to be achieved for cluster investigations. Originally, it was a formatted card based system, which divides into open clusters (OCL), associations (ASS) and globulars (GSC).*
Frankly these ol' numbers are really only useful for research purposes and have been superseded by Lynga's numbers in "5th Catalogue of Open Clusters" or Dias' “New Catalog of Optically Visible Open Clusters and Candidates” (2002).
Most catalogues really prefer NGC, IC, etc.
However, best of all now much of this is now available at the WEBDA database ( http://www.univie.ac.at/webda/ ) You can inspect the OCL data via the "Navigation" Page - typing in the cluster in question. I.e. Example :- NGC 4103 in Crux (See http://www.univie.ac.at/webda/cgi-bin/ocl_page.cgi?cluster=NGC+4103 )
To read the references in the OCL data, see Budapest bibliography and click on the link in "Query". Data displayed is between years or can be searched on the linked page. Because of this now being available electronically, I only recently tossed out all the cards into the recycled rubbish bin!)

Another useful site on open clusters is Dias' one entitled "Open Clusters and Galactic Structure"
( http://www.astro.iag.usp.br/~wilton/ ), which I occasionally use. I has heaps of links to useful papers. (other than OCL, sadly...)

You might like to read my more general open cluster page under the section "Modern Open Cluster Catalogues" http://homepage.mac.com/andjames/Page03003.htm

Hope this helps...
Cheers :thumbsup:

* If you have more specific questions, I'd be happy to say more.

[stephenb]

Hi Molly, sorry, xxx was referring to a 3-digit number, but I can see the confusion.

Enchilada, you've nailed it thanks!

I am reformatting a lot of my DSO lists and I keep coming across the "OCL" reference. Personally, I don't really need to refer to it for practical reasons in my observational work. All these "OCL" objects have NGC/IC numbers anyway.

However, "OCL" and "GSC" would be a quaint way to catagorize open cand globular clusters. These objects get lost in the formalised mass of NGC numbers.

[Enchilada]

Here is a definitive pdf list for you, with the OCL numbers, positions and associated catalogue to cross reference.

Hope this helps.. :thumbsup:

[glenc]

These two recent OC catalogues maybe of interest too:

Catalogue of Open Cluster Data (COCD) (Kharchenko+, 2005)
http://cdsarc.u-strasbg.fr/viz-bin/Cat?J/A%2bA/438/1163

109 new Galactic open clusters (Kharchenko+, 2005)
http://cdsarc.u-strasbg.fr/viz-bin/Cat?J/A%2bA/440/403

They were made by searching the All-sky Compiled Catalogue of 2.5 million stars (Kharchenko 2001)
http://cdsarc.u-strasbg.fr/viz-bin/Cat?I/280A