National Astronomical Observatory of Japan

First Light with the ALMA Band 1 Receiver

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ALMA Band 1 receiver cartridges assembled by ASIAA. (Credit: ASIAA) Original size (1.6MB)

An international team has developed, assembled, and integrated a new set of receivers for the Atacama Large Millimeter/submillimeter Array (ALMA), the Band 1 receivers, which have now been installed for the first time in ALMA antennas and successfully achieved the first light. With ALMA’s lowest frequency receivers, astronomers can view the cool Universe as never before.

As a part of the East-Asian ALMA Development program, the Band 1 receiver project is led by the Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA) in Taiwan, in collaboration with the National Astronomical Observatory of Japan (NAOJ), the NRC Herzberg Astronomy and Astrophysics Research Centre in Canada, the National Radio Astronomy Observatory (NRAO) in the US, and the Universidad de Chile (UCh).

For any new receiver, the successful ‘first light’ marks a major breakthrough as it is the first time that an astronomical signal (light) goes through the entire telescope, from the antenna that is collecting the light, through the receiver with all the backend electronics, to a computer screen at the end of the chain, displaying the result. It is the ultimate test that design, fabrication, and assembly are all perfect. After around 10 years of hard and meticulous work, the Band 1 receiver successfully achieved first light with successful observations of the edge of the Moon on 14 August 2021, followed by the first successful interferometry test observations with two antennas with Band 1 receivers on 17 August, and the acquisition of the first radio spectrum on 27 August. During the test observations, the new receivers successfully received signals from various objects from near to far, including planets (Venus, and Mars), evolved stars and molecular clouds (Orion KL and VY Canis Majoris) in our Galaxy, and extra-galactic distant quasars (3C 279), and the team confirmed the receiver’s performance.

The Band 1 receiver, once installed on all 66 ALMA antennas, will break new ground in various science areas. The new receiver will allow astronomers to peer out at the distant redshifted Universe further than any other receiver on ALMA. Band 1 is also much anticipated to make the next breakthrough discoveries in the study of planet formation. The production of receivers for all ALMA antennas is currently being completed in Taiwan with the goal of offering this new band for open-use observations from Cycle 10, starting in October 2023.

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