On October 23, an interferometer test was conducted using three Japanese 7-m antennas and a Japanese correlator installed at the Array Operations Site (AOS) at 5000 m asl, and interference fringes were successfully obtained.

The observed object is the quasar 3C454.3 which is located about 7 billion light-years away in Pegasus. Three antennas were directed toward the object and radio waves received by each antenna were converted to digital signals, and then, these digital signals were sent to the ACA Correlator and synthesized. This successful test demonstrated that the three antennas worked as a single big radio telescope. The three 7-m antennas used in the test are a part of the Atacama Compact Array (ACA) System manufactured by Japan. The construction of the ACA System is well under way.

The picture shows the three 7-m antennas installed at the AOS. A larger one (far left) is a Japanese 12-m antenna. [Photographed by Joaquin Collao]