METHODS AND RESULTS OF AN OPTICAL-SEARCH FOR EXTRATERRESTRIAL CIVILIZATIONS

The prospects for searches for optical signals arriving from extraterr estrial civilizations are discussed. Two criteria for an artificial or igin for optical emission are analyzed - intensity variations with a a semiotic time structure and the presence of narrow laser lines. We pr opose to attempt to detect and study these signals by investigating '' suspicious'' astronomical objects with extremely high time resolution, 10(-7)s. We will use the special hardware/software photometric comple x MANIA (Multichannel Analysis of Nanosecond Intensity Alterations), w hich consists of a photometer, a ''time-code'' converter that is the r ecording system, a PC/AT 486 computer, and a tape recorder. Special st atistical methods and programs for the search and analysis of any type of brightness variability of astronomical objects on time scales from 10(-7) - 10(2)s are described. The criteria for choosing objects to b e included in the search for extraterrestrial civilizations signals ar e discussed. We propose to search for Type I civilizations by investig ating 161 stars of spectral types F9V-G5V within 25 pc of the Sun. As possible beacons (transmitters) of Type II extraterrestrial civilizati ons, we propose to consider objects that have unusual characteristics, in particular, hueless optical spectra. The results of observations o f 60 objects and the limits for the power of possible signals are repo rted.