The object also appeared out of nowhere. It just wasn't there before. In fact, they don't even know where it is exactly located because it didn't behave like anything they know. Apparently, it can't be closer than 130 light-years but it can be as far as 11 billion light-years away. It's not in any known galaxy either. And they have ruled out a supernova too. It's something that they have never encountered before. In other words: they don't have a single clue about where or what the heck this thing is.
The shape of the light curve is inconsistent with microlensing. In addition to being inconsistent with all known supernova types, is not matched to any spectrum in the Sloan Digital Sky Survey database.
The only thing the astronomers—working on the Supernova Cosmology Project—can tell is that it appeared all of the sudden in the direction of a cluster with the catchy name of CL 1432.5+3332.8, about 8.2 billion light-years away. Hubble caught a spark that continued to brighten during a 100-day period, peaking at the 21st magnitude, only to fade away in the same period of time.