In 1977 a search for extraterrestrial intelligence at the Ohio State University Radio Observatory recorded a strong, narrowband, and apparently intermittent emission near the 21 cm hydrogen line. The detection displayed the antenna pattern signature of a transiting celestial radio source but was not repeated in subsequent transit observations. The event has been advanced by some as a candidate interstellar signal and dismissed by others as probable interference; no independent attempt to replicate the event with a spectral resolution comparable to Ohio State's has been reported. We used the Very Large Array to search for a possible underlying source–artificial or natural–which could account for the detection by occasionally brightening because of scintillation, intrinsic variability, or some other mechanism. With a sensitivity greater than 100 times the original observations, we found two continuum sources within the Ohio State coordinate error boxes, but they displayed no unusual spectral features, showed no sign of flux variability, yielded normal spectral indices based on additional observations at 6 cm, and were too weak to account for the Ohio State detection. No narrow-bandwidth point sources were detected over a band of 1.5 MHz to a flux limit of about 20 mJy at the nominal coordinates. We conclude that the ``Wow'' was not due to a continuous source usually below Ohio State's several jansky detection threshold but occasionally increasing in flux by a factor of less than ∼100. Our search does not significantly constrain the possibility of intermittent sources because we dwelled for only 5-22 minutes per field.
Extraterrestrial Intelligence - Radio Lines: General