Addendum - authorship of 'Photo 51' Naomi Attar, Genome Biology 15 May 2013 In this article, I (the author) followed multiple sources in referring to 'Photo 51' as the work of Rosalind Franklin. However, medical geneticist Jim Lupski raised a query about the accuracy of the attribution, having received correspondence from Jim Watson which mentioned in passing that Ray Gosling had taken the photo. I put the query to Gosling, who confirms that he was indeed 'Photo 51' photographer: 'It was part of the program that Rosalind and I were carrying out to check the effect of the humidity on the crystallization of DNA. This was the 51st of that program, and I was the one who took that particular diffraction pattern.' Thanks to Jim Lupski for bringing the inaccuracy to my attention, to Ray Gosling for providing further information, and to Jim Watson for confirming that this was his understanding of events. Competing interests I am the author of the article.