From Cosmic Dawn to Planet Birth: ALMA Cycle 12 Observations Set to Begin

The Atacama Large Millimeter/submillimeter Array (ALMA) is proud to announce the launch of Cycle 12, which will officially begin on 1 October 2025, marking the start of another highly anticipated observing cycle. This cycle was once again highly competitive: ALMA received 1,640 proposals requesting more than 30,000 hours on the 12-meter Array, corresponding to an oversubscription rate of 7.0. These numbers confirm the continued strong demand for ALMA time and the broad scientific interest of the international astronomy community.

Proposals were reviewed through two complementary approaches. Large Programs were evaluated by the ALMA Proposal Review Committee (APRC), composed of 18 members and a chair, supported by 79 external Science Assessors, who together examined 43 proposals and recommended six Large Programs for Cycle 12. These projects span the cosmos, from the emergence of dust and obscured star formation at cosmic dawn, to the formation of star clusters, the assembly of galaxies through mergers, and the birth of planets around the most common stars in our galaxy, the Milky Way. At the same time, more than a thousand scientists participated in the distributed peer review process, submitting nearly 16,000 evaluations of regular proposals. This broad community involvement ensures both fairness and diversity of expertise in shaping ALMA’s science program.

Accepted proposals were assigned one of three priority grades. Grade A, limited to about one-third of the available time, represents the highest priority, while Grade B adds additional high-priority projects. Together, Grades A and B account for 4,170 hours on the 12-meter Array, which is slightly below the nominal 4,300 hours due to the expected carryover of unfinished projects from Cycle 11. Grade C proposals, which exceeded the available time, were also included as contingencies to maximize scheduling flexibility and utilize weather conditions effectively.

Cycle 12 continues to show a balanced distribution of scientific topics, with strong demand across all five ALMA science categories: cosmology and the high-redshift universe, galaxies and galactic nuclei, the interstellar medium and star formation, circumstellar disks and exoplanets, and stellar evolution and the Sun. Bands 6 and 7 remain the most requested receivers, while Bands 9 and 10 were highly competitive, with more than half of the submitted projects accepted across Grades A, B, and C. In total, only 13% of the requests for 12-meter Array time were accepted with high priority, underscoring the challenge and prestige of securing observing time with ALMA.

ALMA warmly thanks the members of the APRC, the external Science Assessors, and the more than 1,000 reviewers worldwide whose dedication makes this process possible. With Cycle 12 observations beginning on October 1, 2025, ALMA is poised once again to push the frontiers of knowledge — from the cosmic dawn of galaxies to the birthplaces of planets — enabling discoveries that will reshape our understanding of the Universe.

Additional Information

ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSTC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ.

Images