Proposal Review Process
A total of 1661 proposals were submitted in response to the ALMA Cycle 5 Call for Proposals. The proposals were reviewed during a meeting in Antwerp (Belgium) on June 18–23. The review committee consisted of 146 Science Assessors grouped into 18 ALMA Review Panels (ARP) that were distributed across five scientific categories: 1. Cosmology and the high redshift universe (4 panels) 2. Galaxies and galactic nuclei (4 panels) 3. ISM, star formation and astrochemistry (4 panels) 4. Circumstellar disks, exoplanets and the solar system (4 panels) 5. Stellar evolution and the Sun (2 panels). The Review Panels in Categories 1-4 contained eight Science Assessors each, while the Panels in Category 5 contained nine members each. Science Assessors were selected on the basis of scientific specialization while having a regional affiliation that closely matched the nominal ALMA regional shares of observing time. The full list of Cycle 5 Science Assessors is provided in the Appendix. The 18 Panel Chairs served on the ALMA Proposal Review Committee (APRC) together with the APRC Chair, Anneila Sargent. The Review Panels conducted the initial scientific reviews and recommended which Large Proposals should be further discussed by the APRC. The APRC conducted the final review to recommend which Large Programs should be scheduled. The Joint ALMA Observatory (JAO) created an observing queue and assigned a priority grade to each proposal after considering the scientific rank determined from the review process, the share of observing time for each region, and scheduling feasibility. Priority Grade A was assigned to the highest ranked proposals. Grade B was assigned to high ranked proposals while maintaining balance of time across Grade A and B. Grade C was assigned to proposals that oversubscribed the time in a configuration by up to 50%.
Proposal statistics
Of the 1661 proposals submitted, 132 received the highest priority of Grade A, 301 received Grade B, and 262 received Grade C. The Grade A and B proposals requested an estimated 3706 h of execution time on the 12-m Array. Together with the estimated 300-400 h of Cycle 4 Grade A proposals that will be carried forward to Cycle 5, this constitutes the 4000 h of 12-m Array time expected to be available for successful executions in Cycle 5. The titles, investigators, and abstracts of the Grade A and B projects are available from the ALMA Science Portal. Tables 1 and 2 list the number and requested time for proposals grouped by region and science category, respectively. Table 3 lists the number of Grade A and B projects for different proposal types. Various metrics of the proposal data are presented in the figures. Twenty-two Large Proposals were submitted in Cycle 5. As recommended by the APRC, the following four Large Programs were scheduled for Cycle 5: 1. ALMA-IMF: ALMA transforms our view of the origin of stellar masses (2017.1.01355.L) PI: Frederique Motte (EU); co-PIs: Adam Ginsburg (NA), Patricio Sanhueza (EA), and Fabien Louvet (CL) 2.   100,000 Molecular Clouds Across the Main Sequence: GMCs as the Drivers of Galaxy Evolution (2017.1.00886.L) PI: Eva Schinnerer (EU); co-PIs: Adam Leroy (NA), Guillermo Blanc (NA), Erik Rosolowsky (NA), Andreas Schruba (EU), and Annie Hughes (EU) 3.  ALCHEMI: the ALMA Comprehensive High-resolution Extragalactic Molecular Inventory (2017.1.00161.L) PI: Franceso Costagliola (EU); co-PIs Nanase Harada (NA/EA) and Jeffrey Mangum (NA) 4. ALPINE: The ALMA Large Program to INvestigate CII at Early times (2017.1.00428.L) PI: Olivier Le Fèvre (EU); co-PIs: Andreas Faisst (NA), Daniel Schaerer (EU), John Silverman (EA), Paolo Cassata (CL), Lin Yan (NA), Peter Capak (NA), and Matthieu Bethermin (EU) Collectively these four Large Programs were assigned 281 h on the 12-m Array, 745 h on the 7-m Array, and 927 h on the Total Power Array, which represents nearly 20% of the total observing time (10,000 h) available across all arrays in Cycle 5.
Table 2. Distribution of Cycle 5 proposals by scientific category
Table 3. Number of proposals and Grade A & B projects by proposal type
Figure 8. Regional distribution of the Cycle 5 APRC and ARP members