Hello James, Donati’s comet has been described by many of the 19th Century observers who saw it as the most beautiful comet. Both in scale in the sky, in form with the curved dust tail and the thin straight gas tail. It was painted by many artists, whose paintings can be seen by searching for images of this comet on Google.It was an important comet as it was the first comet to be photographed. This feat was achieved intially by an English Portrait Photographer William Usherwood then by G.P.Bond at Harvard Observatory in the USA. My particular favourite painting of this comet is by James Poole and is held at Sheffield Museum 
Denis Buczynski