The configuration group has made substantial progress during the last six months. Both the zoom spiral and donut/doubling-ring strawperson designs now fully implement the topographic constraints of the site. A further convergence in the strawperson array design has been achieved by the zoom spiral design adopting the compact array and ``3 km'' array of the donut/doubling-ring design as the inner and the outer limit of the telescoping design. Memos describing the details of the two competing designs are now available, and reports of other related works can be found at the Configuration Working group web page (http://www.alma.nrao.edu/development/config/index.html). The ASAC strongly urges inclusion of the effects of pointing errors in the simulations and recommends that the ongoing imaging studies be completed and their conclusions reported at one of the next ASAC meetings.
A preliminary conclusion from the ongoing imaging study, using the five test images in the Simulation Image Library, is that the two competing strawperson designs have comparable imaging performance. The only fundamental difference between the two arrays is the way they may be operated. The doubling ring array has five fixed arrays and possible hybrids between them and is reconfigured in bursts. The zoom spiral allows the possibility to be run either as a continuously reconfiguring array or to operate as a variable number of fixed arrays with burst reconfiguration. Assuming the two arrays have comparable imaging capability as suggested by the imaging study, the decision of selecting the final design may be then made based on the operational considerations. Upon the completion of the imaging study, a decision based on the joint discussion between the configuration and the site study groups should be reported to ASAC for the formal endorsement.