Hubble’s mystery object
Back in 2006, astronomers working on the Supernova Cosmology Project found something in the Boötes cluster that they had never seen before. It exhibited a brightening to magnitude 21 and dimming down to magnitude 26 over a 200 day period which might suggest a supernova, but the strange object did not behave like any other known supernova. It had a spectra which was unlike any other cataloged in the vast Sloan Digital Sky Database, and it wasn’t even in any known galaxy. Sky & Telescope had the best synopsis and provides a link to the research paper. Gotta love mystery objects…
