Congrats to Turbo on "A Catalogue of M51 type Galaxy Associations" Turbo writes: It has been a bit over two years now, but our paper has been accepted at Astrophysics and Space Sciences (a peer-reviewed journal published by Springer) and the preprint is on arXiv. http://aps.arxiv.org/abs/0805.1492 Congratulations! =================== The background to this story is kind of interesting. Turbo is actually the name of a pet ferret that Skip Orr had, but I know him by that handle. Several years back, Turbo noticed an odd thing about clusters or associations of galaxies. The smaller galaxies in the association seemed to have higher-than-average redshift. It is not clear if this was a just a mirage caused by some artificial skewing of the data that somehow crept in, or whether it was real. So the way to check that was to do a more careful survey and see if it held up. they carried it out and produced some solid work, now accepted for publication by Astrophysics and Space Science I gather that the original issue that got Turbo started on this is not settled (correct me if I am wrong) but what happened is what often happens in science. By doing a careful survey, and assembling a bunch of data where before there were gaps which they filled in, they raised several new questions about this class of galaxies. So there is a kind of seredipity operating. That is my take on it, more or less off the cuff and at first sight. It would be interesting to hear what Turbo has to say at this point about the survey and the catalogue. Turbo (turbo-1) is a long-time PFer. His profile https://www.physicsforums.com/member.php?u=9551 says "amateur astronomer" Chances are you've already met him in the various PF forums.