The BAAVSS is one of the oldest-established variable star groups, and has continuous observations stretching back over 100 years. From a heavy dependence on Mira Stars up to the mid-70's, their programme has now shifted towards less-predictable objects such as Dwarf Novae. Includes observers not only from Britain, but all over the world.
Formed not too long after the BAAVSS, the AAVSO holds the largest database of variable star observations in the world. Like the BAA, they concentrated initially on Mira stars, but now have all sorts of stars on their books. Their ranks include both amateur and professional astronomers
Another long-established body, the AFOEV is now based at the well-known CdS in Strasbourg, and includes many famous observers, both past and present, among its members. Their well-structured site is in both English (for the benefit of the cowardly!) and French for us Francophiles! Their charts are usually based on those of the AAVSO, but also include some "foreigners" such as the FU Orionis star V1515 Cyg. There's an extensive chart catalogue thoughtfully based on constellation (which could do with a little bit of tidying up here and there!)
Doing exactly what it says on the tin, this is really one for the advanced observers! It is a network of astronomers, mostly using CCD cameras, to observe faint and newly-discovered eruptive variables. Its messages are quite light-hearted and chatty among the wealth of high-powered observing, which is nice. A really good, easy to navigate, website to which I shall be returning again and again.
TA, as it is universally known and loved, is a magazine dedicated to rapid publication of astronomical news and observations. In the good old days when I used to contribute to it, it was a hand-duplicated, typewritten (remember typewriters?) amalgam of jottings, musings and of course observations. Even then, it was clear that variable stars were a big thing, and there were times when variables threatened to take over the magazine. Well, now they have!
These days, it is better described as a group ratrher than a magazine, what with instant electronic communication having largely replaced the need for that exciting brown envelope popping through the letter box.
TA was responsible for engendering such active groups as the Binocular Sky Society and the Webb Society. Its contributors have included such first-magnitude stars as George "Mr. Novae" Alcock, James Muirden, Patrick Moore, John Isles, John Larard, Michel Verdenet (come to think of it, some of those ought to be zero-magnitude stars!) and others, as well as some young upstart from East Anglia by the name of Poxon.
Good, easy-to-navigate site which, while not a variable-star site per se, carries a lot of useful links. Especially useful for children and teachers.
This is only a selection of groups whose sole, or main, interest is Variable Stars. Many of their sites contain links to other people and organisations. Happy clicking!