On May 30, radio waves emitted by a variable star VX Sagittarii were collected by a Japanese 7-m antenna and a 12-m antenna, and interference fringes were successfully obtained. These results demonstrated that the two antennas are properly linked as an interferometer.

Out of 66 ALMA antennas, Japanese team is responsible for manufacturing four 12-m antennas and twelve 7-m antennas. As for the 12-m antennas, all of the four antennas have finished production and acceptance review and are now used in test observations. And as for the 7-m antenna, the first model has passed the acceptance review on May 2 2011, and after the installation and adjustment of the receiver, it achieved “first light” receiving the first radio wave from an astronomical source on May 27. The antennas used in the interferometer test this time are the first Japanese 7-m antenna and the fourth Japanese 12-m antenna. In the test, the antennas also succeeded in receiving radio waves from quasar J1924-292 and a variable star W Hydrae in addition to VX Sagittarii. These sources are often used in test observations for their strong radio emission.

Shin’ichiro Asayama (System Integration Science Team Deputy Team Lead / RF Sr. Engineer at the Joint ALMA Observatory (JAO)) who is working on the adjustment and commissioning of the telescope expressed his joy saying, “We have been working on the adjustment of these two antennas since the handover from NAOJ after the acceptance review. So, we are really delighted with the success of the interferometer test this time”.

Production and acceptance review of 7-m antennas are well underway. The second 7-m antenna has also passed the acceptance review on May 30. It’s not long before these antennas are used for observation as a part of ALMA.

ALMA is a global partnership of Japan/Taiwan, North America and Europe in cooperation with the host country, the Republic of Chile.

Shin’ichiro Asayama (JAO System Integration Science Team Deputy Team Lead / RF Sr. Engineer; second right) and staff celebrating the first light (on May 27) achieved by the first 7-m antenna, showing a graph of the received radio signals. [Photographed by Satoki Matsushita (ASIAA)]

Japanese 7-m antenna (front) and 12-m antenna (right in the back) during the interferometer test. Two bright stars in the upper right of the 7-m antenna are α and β Centauri.
[Photographed by Richard Simon (ALMA)]