Nine possible explanations for the Weird signal were given to the public in the survey: (1) stellar activity, (2) other astronomical source, (3) a satellite, (4) local interference, (5) instrumental glitch, (6) error in data acquisition, (7) error in data processing or calibration, (8) pattern in noise or (9) signal from aliens (a tenth possibility, “other explanation” was also included).

Nearly 800 people participated in this informal survey (including more than 60 astronomers); the consensus was that the most likely explanation was either (1) or (2), namely an astronomical phenomenon (see figure below).

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After a careful analysis of the observations we performed last Sunday from the Arecibo Observatory, together with SETI Berkeley using the Green Bank Telescope and the SETI Institute’s Allen Telescope Array, we are now confident about the source of the Weird! Signal. The best explanation is that the signals are transmissions from one or more geostationary satellites. This explains why the signals were within the satellite’s frequencies and only appeared and persisted for Ross 128; this star is close to the celestial equator where many geostationary satellites are located.