ALMA "first fringes" at Chajnantor

The first two ALMA antennas linked together as an interferometer on the 5000-metre altitude plateau of Chajnantor. These antennas were used to make the first interferometric measurements of radio signals — so-called “fringes” — of an astronomical source from this site. This is an important technical step for ALMA, as it used a full suite of the production equipment, including two of the 12-metre diameter antennas, and sophisticated electronic systems for receiving and correlating the signals.