SERENDIP (Search for Extraterrestrial Radio Emission from Nearby Developed Intelligent Populations) is an on-going SETI program conducted by the University of California, Berkeley. It is unusual in being a "piggyback" search, operating alongside conventional radio astronomy observations. Since it began, in 1979, it has undergone a series of upgrades.
SERENDIP I was the first phase of the SERENDIP program which began in 1979 using a 100-channel spectrum analyzer installed at the Hat Creek Observatory. SERENDIP II, thousands of times more powerful than its predecessor. It ran from 1986 to 1988 and was primarily located at the 92-meter (300-foot) radio telescope at Green Bank. It was capable of searching 65,000 channels simultaneously.
SERENDIP III was the third incarnation of SERENDIP, led by Stuart Bowyer, which began piggyback operation at the Arecibo radio telescope on April 15, 1992. The SERENDIP III equipment examined 4.2 million channels every 1.7 seconds in a 12 MHz-wide band centered at 429 MHz (equivalent to a wavelength of 70 centimeters). During 10,000 hours of observation time, between 1992 and 1996, the project looked at 93 percent of the sky visible from Arecibo at least once, and 43 percent of the visible sky at least 5 times. Around 100 trillion channels were examined at very high sensitivity. Data analysis, which is still in progress, has turned up a few interesting candidate signals but nothing that strongly suggests an artificial extraterrestrial origin.
SERENDIP IV was installed at the Arecibo radio telescope in June 1997. It was 40 times more sensitive than SERENDIP III, and could examine 168 million frequency channels every 1.7 seconds in a 100 MHz band centered at 1.42 GHz. Signals that peaked significantly above the background noise were stored and the data transferred across the Internet to the SERENDIP laboratory at Berkeley. There the data were passed through a series of algorithms designed to reject radio frequency interference and sift out signals that had some possibility of being both artificial and extraterrestrial. SERENDIP IV instrumentation was also used by the Australian SETI group at the Parkes Telescope and by the Italian SETI group at Medicina. A 4-million-channel version of SERENDIP IV was in operation at the Ohio State University Radio Observatory.
1. Bowyer, S., Zeitlin, G., Tarter, J., Lampton, M., and Welch, W. "The Berkeley Parasitic SETI Program," Icarus, 53, 147 (1983).