ALMA Construction

Al Wootten

At the 2900m elevation Operations Support Facility (OSF), interferometry continued between the two most recently accepted antennas, while the first was readied for transport to the 5000m Array Operations Center (AOS) in mid-September. The first production Optical Pointing Telescope arrived and passed its acceptance tests. The second quadrant of the 64-antenna correlator arrived and was installed at the AOS Technical Building. With the installation of this quadrant, the 64 antenna correlator can process data from 32 antennas. A correlator to handle data from the 16 element Atacama Compact Array (ACA) was installed some time ago. Installation of electrical and fiber connections to the antenna pads is underway, in synchrony with the construction of the antenna access road network. The stations in the ACA area are complete except for connections; those are under way now.

Figure 1

Figure 1 In this panoramic time lapse view the AOS TB is in the distance at the right below Cerro Chajnantor; the ACA antenna stations lie in the foreground


The first antenna will be transported in mid-September to station 106 which is adjacent to the Technical Building. Here, the first high altitude tests of the antenna, the receiver, and the complete ALMA production system will begin. Several antennas will be stationed at the AOS and will be doing interferometric tests of the system by year’s end.

Figure 2

Figure 2 Attendees at the review of the commissioning plans for ALMA visited the AOS on 1 September. In the Technical Building they inspected the second quadrant of the correlator, then undergoing provisional acceptance on-site. In this photo, l-r: L. Testi, P. Schilke, R. Rao, R. Wilson (back), R. Hills, M. Wright, A. Wootten, M. Wright, A. Saez.


A Review, chaired by R. Wilson (CfA), was held at the OSF on 2-3 September, covering the Commissioning and Science Verification plans for the array. Attendees were able to monitor interferometric tests between two antennas as well as total power tests of another antenna. In addition, participants were able to visit the site erection facilities of the antenna contractors, where more than a dozen other antennas are in various stages of construction and final testing.