Trumpler

[bish]

Hello all. There is a small open cluster close to the perseus double that my software labels TR2. My limited understanding is that the trumpler system is a means of classification (ie properties) rather than a 'list' such as Messier or NGC? Is Tr2 a recognised label such as with NGC, or just a description? Thanks.

[acey]

It's both - there's a Trumpler classification of clusters, and also a list of Trumpler clusters, with Tr2 being one of them. The second link below summarises his system, the third link is to Trumpler's original paper from 1930. Trumpler examined photographs (the Franklin-Adams plates) and found 334 clusters, most of which had already been catalogued in NGC, IC or by Melotte; but he also found 37 not previously catalogued, which he listed as "anonymous". These are the ones now named after him. Table 16 of the paper gives his classification list: the cluster which he called "An. 2" (now called Trumpler 2) has classification II3p.

Robert Julius Trumpler - Wikipedia, the free encyclopedia

http://www.astrophoton.com/trumpler_class.htm

http://adsabs.harvard.edu/abs/1930LicOB..14..154T

[bish]

Many thanks for the information.