XO-4 is a star located approximately 863 light-years away from Earth in the Lynx constellation.
[3] A search for a binary companion star using adaptive optics at MMT Observatory was negative.
Koit is Estonian for dawn, and was named for a character in a folk tale written by Friedrich Robert Faehlmann.
This exoplanet was discovered in 2008 by the XO Telescope project using the transit method.
[3] It has been named Hämarik, meaning dusk, and referring to a character from the same Faehlmann story featuring Koit.