this information, a team of astronomers collected radial velocity data using the SOPHIE échelle spectrograph to confirm the existence of the candidate KOI-428b in 2010, later named Kepler-40b. In 2011, the same team confirmed candidate KOI-423b, later named Kepler-39b. Citizen scientist participation Since December 2010, Kepler mission data has been used for the Planet Hunters project, which allows volunteers to look for transit events in the light curves of Kepler images to identify planets that computer algorithms might miss. By June 2011, users had found sixty-nine potential candidates that were previously unrecognized by the Kepler mission team. The team has plans to publicly credit amateurs who spot such planets. In January 2012, the BBC program Stargazing Live aired a public appeal for volunteers to analyse Planethunters.org data for potential new exoplanets. This led two amateur astronomers—one in Peterborough, England—to discover a new Neptune-sized exoplanet, to be named Threapleton Holmes B. One hundred thousand other volunteers were also engaged in the search by late January, analyzing over one million Kepler images by early 2012. One such exoplanet, PH1b (or Kepler-64b from its Kepler designation), was discovered in 2012. A second exoplanet, PH2b (Kepler-86b) was discovered in 2013. In April 2017, ABC Stargazing Live, a variation of BBC Stargazing Live, launched the Zooniverse project "Exoplanet Explorers". While Planethunters.org worked with archived data, Exoplanet Explorers used recently downlinked data from the K2 mission. On the first day of the project, 184 transit candidates were identified that passed simple tests. On the second day, the research team identified a star system, later named K2-138, with a Sun-like star and four super-Earths in a tight orbit. In the end, volunteers helped to identify 90 exoplanet candidates. The citizen scientists that helped discover the new star system will be added as co-authors in the research paper when published. Confirmed exoplanets Exoplanets discovered using Kepler data, but confirmed by outside researchers, include Kepler-39b, Kepler-40b, Kepler-41b, Kepler-43b, Kepler-44b, Kepler-45b, as well as the planets orbiting Kepler-223 and Kepler-42. The "KOI" acronym indicates that the star is a Kepler Object of Interest. Kepler Input Catalog The Kepler Input Catalog is a publicly searchable database of roughly 13.2 million targets used for the Kepler Spectral Classification Program and the Kepler mission. The catalog alone is not used for finding Kepler targets, because only a portion of the listed stars (about one-third of the catalog) can be observed by the spacecraft.