title: A search for ultra-narrowband signals of extraterrestrial origin.
abstract: Nearly 200 nearby stars similar to the sun were observed at the 21-centimeter neutral hydrogen wavelength (in the heliocentric frame) with a bandwidth of 1 kilohertz and a resolution of 0.015 hertz, using the Arecibo 305-meter antenna. At this resolution the effects of terrestrial interference are so slight that the detection limit of 4 x 10(-27) watt per square meter was set by receiver noise alone. No evidence of artificial signals was found.
authors.forename: P
authors.initials: P
authors.lastname: Horowitz