Initial results from Harvard all-sky optical SETI

Howard, Andrew W.; Horowitz, Paul; Mead, Curtis; Sreetharan, Pratheev S.; Gallicchio, Jason; Howard, Steve; Coldwell, Charles M.; Zajac, Joseph; Sliski, Alan

doi:10.1016/j.actaastro.2007.01.038

Cited by 57 publications

(42 citation statements)

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“…These searches targeted both stars and galaxies, and more recently stars harboring known exoplanets (Siemion et al 2013). Searches for both continuously transmitting and short duration light pulses in the visible spectrum (optical SETI) have been conducted (Wright et al 2001;Reines and Marcy 2002;Howard et al 2004;Stone et al 2005;Howard et al 2007, Hanna et al 2009, Tellis & Marcy 2015, Abeysekara et al 2016. A unique search for near-infrared pulses has also begun (Wright et al 2014c, Maire et al 2014.…”

Section: Introductionmentioning

confidence: 99%

“…A high-intensity, diffraction-limited optical laser beam could transmit data at a high rate (exceeding 10 12 bits per second) over Galactic distances, while keeping beam opening angles narrow, well under an arcsecond, minimizing leakage and eavesdropping (Townes & Schwartz 1961;Wright et al 2001, Howard et al 2007). The pencil beams afforded by Optical and IR radiation allow for low relative transmission powers and privacy.…”

Section: Introductionmentioning

confidence: 99%

“…Commensal, beam-forming radio observations with the future MeerKAT array and the Square Kilometer Array, (Siemion et al 2014) would be 100x more sensitive to SETI radio signals than prior searches and would have the ability to survey millions of stars and galaxies limited by back-end compute power. The interest in optical and near-infrared extraterrestrial laser emission has spurred searches for pulses having duration as short as a nanosecond or displaying periodicities (Howard et al 2004(Howard et al , 2007Korpela et al 2011;Drake et al 2010;Mead 2013;Covault 2013;Leeb et al 2013;Gillon 2014;Wright et al 2014ab). …”

Section: Introductionmentioning

confidence: 99%

“…Cocconi & Morrison 1959;Drake 1961;Horowitz & Sagan (1993) ;Tarter 2001;Howard et al 2007;Hanna et al 2009;Siemion et al 2013;Wright et al 2014a;Wright et al 2016;Lacki 2016)). Searches have been conducted at radio wavelengths with Arecibo, Green Bank telescope, Parkes radio telescope, and the Allen telescope array (Drake 1961;Werthimer et al 2001;Korpela et al 2011;Siemion et al 2013, Tarter et al 2011, and Harp et al 2015.…”

Section: Introductionmentioning

confidence: 99%

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A Search for Laser Emission with Megawatt Thresholds from 5600 FGKM Stars

Tellis¹,

Marcy²

2017

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We searched high resolution spectra of 5600 nearby stars for emission lines that are both inconsistent with a natural origin and unresolved spatially, as would be expected from extraterrestrial optical lasers.The spectra were obtained with the Keck 10-meter telescope, including light coming from within 0.5 arcsec of the star, corresponding typically to within a few to tens of au of the star, and covering nearly the entire visible wavelength range from 3640 to 7890 Å. We establish detection thresholds by injecting synthetic laser emission lines into our spectra and blindly analyzing them for detections. We compute flux density detection thresholds for all wavelengths and spectral types sampled. Our detection thresholds for the power of the lasers themselves range from 3 kW to 13 MW, independent of distance to the star but dependent on the competing "glare" of the spectral energy distribution of the star and on the wavelength of the laser light, launched from a benchmark, diffraction-limited 10-meter class telescope. We found no such laser emission coming from the planetary region around any of the 5600 stars. As they contain roughly 2000 lukewarm, Earth-size planets, we rule out models of the Milky Way in which over 0.1% of warm, Earth-size planets harbor technological civilizations that, intentionally or not, are beaming optical lasers toward us. A next generation spectroscopic laser search will be done by the Breakthrough Listen initiative, targeting more stars, especially stellar types overlooked here including spectral types O, B, A, early F, late M, and brown dwarfs, and astrophysical exotica.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Search for Laser Emission with Megawatt Thresholds from 5600 FGKM Stars

Tellis¹,

Marcy²

2017

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“…There has been growing interest in searches for fast (nanosecond) optical pulses emanating from transmitting beacons from extraterrestrial intelligence (e.g., Horowitz et al 3 , Werthimer et al 4 , Wright et al 5 , Reines & Marcy 6 , Howard et al 7 , Stone et al 8 , Howard et al 9 , Covault 10 ). Today's highest-powered pulsed lasers can outshine our Sun by at least 4 orders of magnitude in brightness, and may offer one of the best means for interstellar communication (as originally suggested by Schwartz & Townes 11 ).…”

Section: Introductionmentioning

confidence: 99%

A near-infrared SETI experiment: instrument overview

Wright

Werthimer

Treffers³

et al. 2014

SPIE Proceedings

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We are designing and constructing a new SETI (Search for Extraterrestrial Intelligence) instrument to search for direct evidence of interstellar communications via pulsed laser signals at near-infrared wavelengths. The new instrument design builds upon our past optical SETI experiences, and is the first step toward a new, more versatile and sophisticated generation of very fast optical and near-infrared pulse search devices. We present our instrumental design by giving an overview of the opto-mechanical design, detector selection and characterization, signal processing, and integration procedure. This project makes use of near-infrared (950 -1650 nm) discrete amplification Avalanche Photodiodes (APD) that have > 1 GHz bandwidths with low noise characteristics and moderate gain (~10 4 ). We have investigated the use of single versus multiple detectors in our instrument (see Maire et al., this conference), and have optimized the system to have both high sensitivity and low false coincidence rates. Our design is optimized for use behind a 1m telescope and includes an optical camera for acquisition and guiding. A goal is to make our instrument relatively economical and easy to duplicate. We describe our observational setup and our initial search strategies for SETI targets, and for potential interesting compact astrophysical objects.

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Interstellar communication: The colors of optical SETI

Hippke

2018

J Astrophys Astron

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It has recently been argued from a laser engineering point of view that there are only a few magic colors for optical SETI. These are primarily the Nd:YAG line at 1,064 nm and its second harmonic (532.1 nm). Next best choices would be the sum frequency and/or second harmonic generation of Nd:YAG and Nd:YLF laser lines, 393.8 nm (near Fraunhofer CaK), 656.5 nm (Hα) and 589.1 nm (NaD2). In this paper, we examine the interstellar extinction, atmospheric transparency and scintillation, as well as noise conditions for these laser lines. For strong signals, we find that optical wavelengths are optimal for distances d kpc. Nd:YAG at λ = 1,064 nm is a similarly good choice, within a factor of two, under most conditions and out to d 3 kpc. For weaker transmitters, where the signal-to-noise ratio with respect to the blended host star is relevant, the optimal wavelength depends on the background source, such as the stellar type. Fraunhofer spectral lines, while providing lower stellar background noise, are irrelevant in most use cases, as they are overpowered by other factors. Laser-pushed spaceflight concepts, such as "Breakthrough Starshot", would produce brighter and tighter beams than ever assumed for OSETI. Such beamers would appear as naked eye stars out to kpc distances. If laser physics has already matured and converged on the most efficient technology, the laser line of choice for a given scenario (e.g., Nd:YAG for strong signals) can be observed with a narrow filter to dramatically reduce background noise, allowing for large field-of-view observations in fast surveys.

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Initial results from Harvard all-sky optical SETI

Cited by 57 publications

References 3 publications

A Search for Laser Emission with Megawatt Thresholds from 5600 FGKM Stars

A Search for Laser Emission with Megawatt Thresholds from 5600 FGKM Stars

A near-infrared SETI experiment: instrument overview

Interstellar communication: The colors of optical SETI

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