Enlarge / Kepler was made to find planets, but it’s found other uses. (credit: Kepler)

The Kepler planet-hunting telescope was designed to do one thing: gather data from a single portion of the sky often enough to catch rare, brief events. The events it was looking for were slight dips in light that happened as a planet passed in between its host star and Earth. But it captured other transient events as well. Some of these other events were supernovae—the explosion of massive stars—and Kepler captured two just as the explosion burst through their surface.

But at least one of the brief events Kepler observed was so odd it wasn’t originally recognized as a supernova. It was only after the observatory’s data was released to the entire research community that people started proposing that something so bright was most likely a supernova. Now, researchers are offering an analysis of why this event looked so strange.

With their typical flair for the dramatic, the researchers have termed this event KSN 2015K. As mentioned above, it looked different enough from other supernovae that it wasn’t picked up by a standard analysis. In addition, the researchers found that the same event was spotted by a couple of surveys dedicated to identifying supernovae at an early stage. Neither of those surveys identified it, either.