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Search for Nanosecond Optical Pulses from Nearby Solar‐Type Stars

Howard, Andrew W. and Horowitz, Paul and Wilkinson, David T. and Coldwell, Charles M. and Groth, Edward J. and Jarosik, Norm and Latham, David W. and Stefanik, Robert P. and Willman, Alexander J., Jr. and Wolff, Jonathan and Zajac, Joseph M. (2004) Search for Nanosecond Optical Pulses from Nearby Solar‐Type Stars. Astrophysical Journal, 613 (2). pp. 1270-1284. ISSN 0004-637X. doi:10.1086/423300.

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With "Earth 2000" technology we could generate a directed laser pulse that outshines the broadband visible light of the Sun by 4 orders of magnitude. This is a conservative lower bound for the technical capability of a communicating civilization; optical interstellar communication is thus technically plausible. We have built a pair of systems to detect nanosecond pulsed optical signals from a target list that includes some 13,000 Sun-like stars, and we have made some 16,000 observations totaling nearly 2400 hr during five years of operation. A beam splitter-fed pair of hybrid avalanche photodetectors at the 1.5 m Wyeth Telescope at the Harvard/Smithsonian Oak Ridge Observatory (Agassiz Station) triggers on a coincident pulse pair, initiating measurement of pulse width and intensity at subnanosecond resolution. An identical system at the 0.9 m Cassegrain at Princeton's Fitz-Randolph Observatory performs synchronized observations with 0.1 μs event timing, permitting unambiguous identification of even a solitary pulse. Among the 11,600 artifact-free observations at Harvard, the distribution of 274 observed events shows no pattern of repetition, and is consistent with a model with uniform event rate, independent of target. With one possible exception (HIP 107395), no valid event has been seen simultaneously at the two observatories. We describe the search and candidate events and set limits on the prevalence of civilizations transmitting intense optical pulses.

Item Type:Article
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Howard, Andrew W.0000-0001-8638-0320
Latham, David W.0000-0001-9911-7388
Additional Information:© 2004 American Astronomical Society. Received 2004 March 16 Accepted 2004 June 11 The Harvard SETI group gratefully acknowledges the enlightened and continued support of the Planetary Society (TPS) and the Bosack-Kruger Charitable Foundation, and additional support from the SETI Institute. The Princeton SETI group thanks Eric Tilenius, Princeton University, and the Princeton University Physics Department for financial support. We are indebted to the night observers at Oak Ridge Observatory and at the Fitz-Randolph Observatory for their tireless efforts that bring us so many photons. We particularly thank Joe Caruso and Guillermo Torres at ORO, and Herman Ashley, Rhonda and Richard Gillingwater, Maggie Kirkland, Mark Lopez, Joseph Maffei, Paul Mark, John Miller, Aaron Schomburg, James Wray, and others (Willman 2004) at FRO. We thank also Chris Clearfield, Jason Gallicchio, Chris Laumann, Alan Sliski, Pratheev Sreetharan, and Anne Sung at Harvard.
Funding AgencyGrant Number
Planetary Society (TPS)UNSPECIFIED
Bosack-Kruger Charitable FoundationUNSPECIFIED
Princeton UniversityUNSPECIFIED
Princeton University Physics DepartmentUNSPECIFIED
Subject Keywords:astrobiology; extraterrestrial intelligence; instrumentation: detectors; techniques: photometric
Issue or Number:2
Record Number:CaltechAUTHORS:20170705-085000095
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Official Citation:Andrew W. Howard et al 2004 ApJ 613 1270
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78750
Deposited By: Ruth Sustaita
Deposited On:05 Jul 2017 22:17
Last Modified:15 Nov 2021 17:42

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