October 11, 2016 - 14:00 PDT

Breakthrough Listen​
at UC Berkeley to conduct follow up observations of reported anomalous
spectral features in solar type stars.
A​ recent paper entitled ​“Discovery of peculiar periodic spectral modulations in a small fraction of solar typestars” ​by Borra and Trottier (2016), Université Laval, Quebec​, reports the detection of periodic spectral
modulations in 234 out of 2.5 million stars observed by the Sloan Digital Sky Survey (SDSS). Authors Borraand Trottier state that the signal is consistent with a prediction from an ​earlier paper​ by Borra, for signals
from extraterrestrial civilizations broadcasting extremely rapid (shorter than 0.1 nanoseconds) optical pulses
superimposed on the light of the host stars.
The one in 10,000 objects with unusual spectra seen by Borra and Trottier are certainly worthy of additionalstudy. However, extraordinary claims require extraordinary evidence. It is too early to unequivocally attributethese purported signals to the activities of extraterrestrial civilizations. Internationally agreed-upon protocols
for searches for evidence of advanced life beyond Earth (SETI) require candidates to be confirmed byindependent groups using their own telescopes, and for all natural explanations to be exhausted before
invoking extraterrestrial agents as an explanation. Careful work must be undertaken to determine false
positive rates, to rule out natural and instrumental explanations, and most importantly, to confirm detections
using two or more independent telescopes.
Peaks in Fourier analysis of stellar spectra, such as those discussed by Borra and Trottier, can be caused
by instrumental optics or introduced during data reduction. Data artifacts, fringing, and inconsistencies in themanufacture of detectors are known to users of high resolution spectrographs to cause minute patterns toappear in the resulting spectra. The movement of the telescope, variations in observing conditions, and theprocess of wavelength calibration can easily introduce undesired signals at levels that are only barelydetectable. It is therefore important to check the claimed signal using a different telescope and instrument.
The ​Berkeley​ SETI ​ Research Center (BSRC) team has added several stars from the Borra and Trottiersample ​ to the ​Breakthrough Listen observing queue on the 2.4-meter​ ​Automated Planet Finder (APF)
optical telescope. The capabilities of the APF spectrograph are well matched to those of the original
detection, and these independent follow-up observations will enable us to verify or refute the reported
detections. We look forward to consulting with Professor Borra and his team on these observations, as wellas additional follow up investigations using other data sources.
The international SETI community has established a 0 to 10 scale for quantifying detections of phenomenathat may indicate the existence of advanced life beyond​ the Earth called the “​Rio Scale.” The BSRC teamassesses the Borra-Trottier result to currently be a 0 or 1 (None/Insignificant) on this scale. If the signal were
to be confirmed with another independent telescope, its significance would rise, though an exhaustive
analysis of other possible explanations, including instrumental phenomena, must be performed before
supporting the hypothesis that artificially generated pulses are responsible for the claimed signal.
The Search for Extra-Terrestrial Intelligence (SETI) is a field of science that attempts to find signatures oftechnology developed by civilizations other than our own. No such signals have yet been found, but large
surveys hold the best promise of expanding the search space sufficiently for a detection to occur.
Breakthrough Listen, whose science program is headquartered​at ​Berkeley SETI Research Center at theUniversity of California, Berkeley's Astronomy Department, is undertaking such a search. BreakthroughListen includes efforts using the ​Robert​ C. Byrd Green Bank Telescope​(GBT) and ​Parkes Observatory toscan for artificial radio signals, as well as a​ program with the ​Automated Planet Finder (APF) at Lick
Observatory searching for emission from extraterrestrial laser technology.

Breakthrough Listen is foremost a scientific program seeking to answer questions surrounding the past or
presence of advanced life
​ in the universe. To such end, ​Breakthrough Listen seeks collaboration withacademic institutions, respective SETI groups and telescopes across the world. ​Breakthrough Listen​ belongs to a portfolio of other ​Breakthrough Initiatives, designed to stimulate scientific discourse in pursuitof humanity’s grandest question; “Are we alone?”.
Contact: bsrc@berkeley.edu
http://seti.berkeley.edu

The Automated Planet Finder at Lick Observatory (Credit: Vogt et al 2014)