Galactic Photobombing article by Nancy_A, image from the galaxyzoo team
Keel said they estimated they could identify 1,100 particularly interesting galaxies, where they thought short-exposure Hubble images would be beneficial for getting more information about the objects. While Galaxy Zoo’s proposal for observing time was accepted by STScI, they were ‘only’ allocated 300 observing slots.
This image of the photobombing galaxies is one of those observations, which the Galaxy Zoo team have nicknamed Zoo Gems. Keel estimates volunteers have probably found over 2,000 of these overlapping galaxies over the years. “A key feature of our project was the wide range of galaxy science goals it could address, so we wanted to keep a broad mix of object types,” wrote Keel. “Some types were rare and had fewer than 10 examples even from Galaxy Zoo, so we started by keeping those. When there were many to choose from, we did what Galaxy Zoo history suggested – asked for people to vote on which merging galaxies, overlapping galaxies, and so on should go into the final list.
Look for more Zoo Gems from the Hubble Space Telescope by following the hashtag #ZooGems on social media.