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Where do variable stars get their names?

From the General Catalog of Variable Stars, we find that the naming convention for variable stars (many of which are X-ray sources) is not as straightforward as you might think. They start at R (instead of A) and go through the alphabet and double alphabet in a non-intuitive way.

Letters # of them
R, S, ..., Z, 9
RR, RS, ..., RZ, SS, ST, .., SZ, TT, ..., ZZ, 45
AA, AB, ..., AZ, BB, ...QZ, 280 (but no J !)
When they get to this point, instead of moving on to AAA or RRR, they go to V and start with the number after the total number of previously named objects (9+45+280).

V335, V336, ...

As of a recent (1995) name list, the total number of designated variable stars has now reached 31,193. Sagittarius has the most of any constellation: it's now up to V4333 Sgr.

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