The selection process for projects is explained in Section 5.1 of the ALMA Cycle 3 Proposers Guide and Capabilities:
"Science observations will be executed by ALMA operations staff, taking into account (in rough order of priority): the weather conditions, the configuration of the array, target elevation and other practical constraints, the projects’ assigned priority group, and executive balance. All other things being equal, the project with the highest scientific rank will be observed."
Proposals will be assessed on the overall scientific merit of the proposed investigation and its potential contribution to the advancement of scientific knowledge. For a full description of the proposal selection process, see Appendix B of the ALMA Cycle 3 Proposers Guide and Capabilities.
ALMA is scheduled dynamically, and so it is not possible to know when a given Scheduling Block will be run. At the telescope, Scheduling Blocks (SBs) are selected from a queue of SBs that match the current conditions (weather, array configuration, target observability). Execution priority is based on the projects’ assigned priority grade and Executive balance. All other things being equal, the project with the highest scientific rank will be observed.
During Cycle 3, the 12-m Array will be arranged in 8 different configurations (see the Technical Handbook, chapter 7). Investigators request a specific target angular resolution and largest angular scale for each science goal. This angular resolution is mapped to one of the 12-m Array configurations that are planned for Cycle 3 (see Table 7.1 in the Technical Handbook). The scheduling software will prioritize scheduling of the science goal when the array is in the best matching configuration, although a slightly more compact or extended configuration may be allowed within the angular resolution tolerances adopted for Cycle 3.
Cycle 3 will start on 2015 October 1st in the most extended configuration (C36-8) and on average there will be a new configuration per month. Observations will not be scheduled in February due to the bad weather conditions during the Altiplanic winter. The configuration schedule is given in Table 3 of the Cycle 3 Proposer's Guide and Capabilities, and minor modifications to the 2016 Cycle 3 schedule may be done as a result of the proposal pressure depending on the results of the proposal review process. The exact dates of re-configurations, in particular during southern winter time, may also depend on the weather situation.
Beginning in Cycle 3, ALMA enters a new phase where PI-science observations dominate activities while continued improvements and developments are also explored. Cycle 3 operations will include standard and non-standard modes, with only non-standard mode observations being conducted on a best-effort basis, while standard modes will no longer be subject to such limitations.
Cycle 3 observations will be continuously scheduled during nighttime in 16h shifts and during part of the week also during day-time (for Bands 3-6), interrupted by periods of engineering and execution of tasks associated with optimization and further development of the Array.
Once Scheduling Blocks have been submitted, PIs (and PI delegates) can follow project activity using the Project Tracker, available off the Science Portal through the link Observing=>Project Tracker, or they may contact their Contact Scientist through the helpdesk. PIs (and PI delegates) have the ability to sign up for email notifications through their user profile in the science portal (login, click on your name in the upper right, and select "profile", then check the "Receive emails" button). This will send an email notification to you (and anyone you delegate) whenever a component of a project is first observed, fully observed, or successfully processed.