Figure 1: The first ALMA production antenna validates the ALMA system through observations of the Moon.
Figure 1: The first ALMA production antenna validates the ALMA system through observations of the Moon.
Figure 2: The first Vertex production antenna is carried into the testing area of the OSF Technical Facility by the transporter on 6 Feb.
On January 22, 2009 scientists and engineers at the Operations Support Facility (OSF) in northern Chile achieved astronomical validation of an ALMA continuum system. The Moon was observed in three of the four bands available in the Front End, tuned to 100 GHz, 240 GHz and 310 GHz.
The sky from this low altitude (2900m) site did not cooperate with an attempt to observe at 675 GHz though signal throughput was attempted by detecting the antenna shutter. The ALMA antenna accepted last month from Japan was used with the receiver assembly from the Front End Integration Center assembled at the NRAO Technology Center in Charlottesville, and a Back End assembled at the Socorro, NM Science Operations Center. The observations were controlled from the OSF Technical Facility supplied by ESO.
On 6 February 2009, the first production antenna designed and built by the Vertex division of General Dynamics Corp. under contract with Associated Universities, Inc. was accepted by the project since it had passed its acceptance tests. An ALMA transporter moved this antenna to a foundation at the nearby OSF and pointing tests began immediately. This antenna will be equipped with the Front End recently delivered from the East Asian Front End Integration Center in Taiwan.
The remaining three Melco and eight Vertex antennas on the site will follow during the course of the year. Major components of the first AEM antenna under contract from ESO have been shipped from Antwerp and these antennas will join the growing ALMA antenna family during the year. Antenna foundation construction continues at the high-elevation Array Operations Site (AOS). Concrete has been poured for 52 foundations. Each of these milestones are important steps that lead to astronomical validation of the fledgling ALMA array later this year.