Overview
- South Africa’s MeerKAT telescope recorded OH absorption at 1665 and 1667 MHz from 3I/ATLAS on October 24, the first radioastronomical signature tied to an interstellar object.
- Measured line parameters include a velocity near −15.6 km/s and widths of roughly 0.9–1.3 km/s, with earlier September attempts yielding no signal.
- The OH lines are interpreted as indirect evidence of water in the coma, reinforcing a cometary explanation and undercutting technological-origins claims.
- Coordinated follow-up is underway as the object approaches its December 19 closest pass to Earth at about 270 million km, with a Juno low-frequency radio search planned for March 16, 2026.
- Some researchers, including Avi Loeb, urge caution pending more data, and an IPN specialist has called for updated classification criteria for future interstellar visitors, as a U.S. lawmaker presses NASA for transparency.