Keck Observatory, Hawaii

Optical SETI: A Spectroscopic Search for Laser Emission from Nearby Stars
Amy Reines

In 1961, Robert Schwartz and Charles Townes suggested that advanced civilizations could use optical lasers as an efficient means of interstellar communication. Today, Optical SETI (OSETI) projects search for highly energetic pulsed lasers and continuous wave lasers. Projects include dedicated searches, piggyback searches, and data mining.

Many OSETI projects search for highly energetic pulsed lasers using photometric techniques. Photometers with two or three photodetectors are used to search for nanosecond laser pulses in broadband visible light. A high powered nanosecond laser can outshine its host star during its brief pulse because starlight is hardly detectable on such a short time scale. Therefore, coincident pulses with a few or more optical photons would stimulate further analysis.

My research includes searching for evidence of extraterrestrial intelligence in the form of narrow-band emission lines in high resolution spectra of ~600 main sequence stars. Most of the stars are within 200 light years of Earth. The stellar spectra have been obtained over the past several years in a search for extrasolar planets using relative radial velocities. Drs. Geoff Marcy, Paul Butler and Steve Vogt have taken roughly 10,000 observations using the HIRES echelle spectrometer on the 10 meter Keck 1 telescope. We search for laser emission lines in the spectra from 4000 Å - 5000 Å by comparing different observations of the same star to one another and looking for statistically significant differences. Our method allows for detections of signals from both high powered pulsed lasers (~1016 W) and moderately powered continuous lasers (~50 kW).

No laser emission lines were found.


Publications:

2002 "Optical Search for Extraterrestrial Intelligence: A Spectroscopic Search for Laser Emission From Nearby Stars", (with G.W.Marcy), Publications of the Astronomical Society of the Pacific, 114, 416.

2001 "Optical SETI: A Spectroscopic Search for Laser Emission From Nearby Stars", Master's Thesis, San Francisco State University.


Links:

Amy Reines: Homepage

SETI Institute

California & Carnegie Planet Search

The Search for Extraterrestrial Intelligence at U.C. Berkeley

SETI@home

Lick Observatory Optical SETI Program

Optical SETI at Harvard/Smithsonian

W. M. Keck Observatory

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