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New Measurements Tighten Mystery of the 1977 'Wow!' Signal

Revised analyses shift focus from local interference to testable astronomical explanations.

A large radio telescope dish beneath a dark, star-filled sky
For 72 seconds in August 1977, an Ohio radio telescope picked up a signal thirty times stronger than the background hum of space, sitting almost exactly on the frequency scientists had guessed an alien civilization would choose — and it has never been heard again

Overview

  • The Big Ear radio telescope recorded a strong, narrowband spike on August 15, 1977 that lasted 72 seconds and was later annotated 6EQUJ5 and dubbed the “Wow!” signal.
  • Big Ear’s meridian‑transit design gave only a 72‑second dwell time and used two offset feed horns, which created a positional ambiguity that prevented immediate re‑observation.
  • Decades of targeted follow‑up observations with instruments including the Very Large Array, Mount Pleasant, Green Bank and the Allen Telescope Array have failed to find any repeat of the signal.
  • A 2025 reanalysis led by Abel Méndez raises the peak flux above 250 janskys and shifts the measured frequency to 1420.726 MHz, findings that the authors say favor a maser‑like flare from a cold hydrogen cloud pumped by a high‑energy event, though the work remains a preprint and not peer reviewed.
  • A newly catalogued Ohio SETI archive of roughly 40,000 transient narrowband events offers a practical route to test the hydrogen‑flare idea by searching for fainter or repeat analogues and will likely drive renewed, systematic reanalysis and coordinated observations.