IRAS F15307- A HYPERLUMINOUS INFRARED GALAXY AT Z=0.93(3252 )

A new hyperluminous infrared galaxy in the IRAS Faint Source Catalog i s identified at a redshift of 0.93. This object has a bolometric lumin osity of approximately 10(13) L., a very large ratio of infrared-to-op tical luminosity, warm dust emission, a ratio of infrared-to-radio flu x densities consistent with other infrared galaxies, and an optical sp ectrum similar to a Seyfert 2 galaxy. IRAS F15307+3552 shares these ch aracteristics and its radio-to-optical spectral energy distribution wi th two other infrared galaxies, F10214+4724 and P09104+4109. Discovery of a third object with these properties defines an extreme subclass o f ultraluminous galaxies powered primarily by star formation. The syst ematic method used to find this object begins the process of determini ng the space density of these most luminous examples of the infrared g alaxy phenomenon.