The
Kepler spacecraft's first days of science activity revealed a series of transit events, in which some body (such as a planet) crosses in front of, and therefore dims, its host star. Such objects were taken from the
Kepler Input Catalog and reclassified as
Kepler Objects of Interest. Kepler-5 was one of these objects of interest, and was given the designation KOI-18. After the stellar parameters were established, the Kepler science team ran models and fits to ensure that Kepler-5's transit event was not a
false positive, such as an
eclipsing binary star. Once the planetary nature of Kepler-5b was established, the Kepler team searched for the planet's
occultation behind its star, hoping to find the temperature on its day side. They found both, and were able to set the
equilibrium temperature of the planet. The use of
speckle imaging using
adaptive optics at the
WIYN Observatory in Arizona and the
Palomar Observatory in California isolated the starlight of Kepler-5 from background stars. Use of the
Fibre-fed Echelle Spectrograph (FIES) at the
Nordic Optical Telescope on the Canary Islands on June 4, 2009 provided data that was used to determine the star's
stellar classification. The
W.M. Keck Observatory's
High Resolution Echelle Spectrometer (HIRES), which was used on June 3–6, 2009, and July 2–4, 2009, determined
radial velocity measurements for the star, which helped to further define stellar parameters. Kepler-5 has, as considered by the Kepler team, the potential for use in the study of planets in extreme conditions; its high temperature, large size, and short
orbital period contribute to the aforementioned conditions. The findings of the Kepler team, which also included planets
Kepler-4b,
Kepler-6b,
Kepler-7b, and
Kepler-8b, were announced at the 215th meeting of the
American Astronomical Society of January 4, 2010. ==Host star==