ALMA Project Status

Al Wootten

Fig. 1

Fig. 1 The first ALMA antenna at the 5050m altitude Llano Chajnantor stands on pad 106. To its left is the Array Operations Site Technical Building that houses the correlator, the central local oscillator, and other equipment beneath the site's spectacularly clear skies. The antenna is controlled entirely from the lower elevation Operations Support Facility, a few dozen kilometers away.


Fig. 2

Fig. 2 Three Vertex antennas, including the newly accepted DV03, stand ready for duty in the OSF test area.


On 23 September, the first antenna delivered to the ALMA Assembly Integration and Verification (AIV) continued a long voyage that had begun in Osaka, Japan, traveling on the transporter to become the first antenna to reach the 5050m Array Operations Site (AOS). Within a little over a week, its pointing had been confirmed and observations of astronomical sources had begun with its sensitive receivers. These observations were the first acquired at the AOS, the first astronomical spectra taken with the 64-element correlator, and the first data taken using the central local oscillator. By the end of October, the antenna will be joined by another antenna as preparations for submillimeter interferometry at the site move forward.

The antenna foundation at the OSF, from which the antenna left for the AOS, didn’t stand vacant for long. Soon DV03, the third Vertex antenna, became the fourth antenna to arrive in the AIV team’s hands. At press time, the team at the OSF was performing tests on four ALMA antennas at the two sites. Single antenna tests were under way at the AOS with the newly repositioned antenna and at the OSF with the newly accepted antenna. The two antennas remaining at the OSF continued their interferometric tests. The spot vacated by the newly accepted antenna left an opening for construction of the next antenna. Nine antennas are in various stages of construction at the Vertex Site Erection Facility. Elements of three additional antennas are located at the Alcatel facility, and three Mitsubishi antennas are being readied for acceptance over the coming weeks. The first of the twelve Mitsubishi 7m antennas, to be located in the Atacama Compact Array, has been shipped from Japan and is expected in a few weeks at the OSF.

Joint ALMA Observatory Newsletter, October 2009