Science Highlight




ALMA Proposal Review

The ALMA proposal review process is organized by the Proposal Handling Team (PHT) at the Joint ALMA Observatory (JAO). ALMA proposals are selected through competitive peer review through either the distributed peer review process or the ALMA Proposal Review Committee (APRC).

Proposals that request less than 50 h on the 12-m Array or less than 150 h on the 7-m Array in standalone mode are reviewed using the distributed peer review system, in which the proposal team designates one member of the proposal team to participate in the review process. The outcomes of the distributed peer review process are:

  • A scientifically ranked list of proposals
  • Individual comments for each proposal written by the reviewers that are sent to the Principal Investigators (PIs).

Large Programs, i.e., proposals that request more than 50 h on the 12-m Array or more than 150 h on the 7-m Array in standalone mode, are reviewed by the APRC, which is a panel composed of experts selected from the international astronomical community. To gain further expert advice, external Science Assessors will provide reviews on Large Programs, which will be considered by the APRC. The outcomes of the APRC review process are:

  • A list of recommended Large Programs
  • A consensus report for each Large Program that summarizes the strength and weaknesses of the proposal.

All proposals are reviewed in a dual anonymous fashion in which the proposers do not know the identity of the reviewers and the reviewers do not know the identity of the proposers. All proposals need to be prepared in accordance with the dual-anonymous guidelines.


Distributed peer review plenary session

The PHT has produced a video that describes distributed peer review, including an overview of the process, guidelines on reviewing proposals, and tips to write reviews for PIs. In addition, the PHT will be hosting a series of live Webinars, during which the PHT will present this video and will be available to answer your questions. Reviewers and mentors are strongly encouraged to view the video or attend one of the Webinars. The Webinars will be held between May 05 and May 11 at different times to accommodate reviewers and mentors in each of the ALMA regions. Reviewers and mentors can attend any one of the six scheduled Webinars that is most convenient to them. The schedule for the six sessions is below:

    Session 1: Thursday May 05, 13:00 UTC

    Session 2: Friday May 06, 19:00 UTC

    Session 3: Monday May 09, 17:00 UTC

    Session 4: Tuesday May 10, 02:00 UTC

    Session 5: Tuesday May 10, 15:00 UTC

    Session 6: Wednesday May 11, 02:00 UTC

The Webinars will be held using Zoom. By May 03, 2022, the PHT will send an email to all reviewers and mentors that provides information on how to register for the Webinars

(Note: the video presently plays in the Firefox, Chrome, Edge and Opera browsers, but not Safari.)

Slides can be downloaded as a PDF file.


Available documents for the proposal review process




Dual-anonymous Guidelines

Provides guidelines for PIs on how to write their proposals in a dual-anonymous fashion

Distributed Peer Review

Detailed description of the distributed peer review process

Guidelines for Reviewers

Guidelines for reviewing proposals and writing comments to the PIs

How to use the Reviewer Tool

Reviewer Tool manual for the distributed peer review process

Frequently asked questions

Contains answers to numerous questions about the dual-anonymous format and distributed peer review


New in Cycle 9


  • All proposals requesting less than 50 h on the 12-m Array will be reviewed through distributed peer review.
  • In their user profile on the Science Portal, reviewers will have the option to provide a list of investigators with which they have a conflict of interest. If this list is provided, a reviewer will not be assigned proposals in which any investigator in their list is a PI, co-PI, or co-I.


Distributed peer review

  • In Cycle 8, reviewers were requested to indicate their scientific expertise by specifying at least three scientific keywords. In Cycle 9, reviewers can specify from one to as many keywords as their expertise requires. Reviewers should update the keywords that indicate their scientific expertise through their user profile on the ALMA Science Portal.
  • Mentors will have read-only access to their mentee's proposal sets through the Reviewer Tool.
  • The minimum length of the comments to PIs from the reviewers has been increased to 200 characters.
  • Stage 2 will extend over a period of two weeks instead of just one as in Cycle 8.


ALMA Proposal Review Committee

  • The APRC will be composed of 16-18 panel members who are experts in one of the five ALMA science categories.
  • To gain further expertise, Large Programs will also be reviewed by external Science Assessors, who will provide written reviews to the APRC but will not participate in the APRC meeting.


Proposal review timeline

Table 1 summarizes the timeline of the Cycle 9 proposal review process. A brief description of each step is given below. Detailed instructions for the distributed peer review can be found here. Instructions for the APRC will be sent separately.


Table 1: Timeline of the Cycle 9 Proposal Review Process



26 April 2022

Deadline for reviewers to provide their scientific expertise and their list of conflicts of interest before proposals are assigned.

04 May 2022

Proposals are released to all reviewers. Stage 1 begins for both distributed peer review and the APRC.

01 June 2022

Stage 1 deadline for all reviewers.

02 June 2022

Distributed peer review Stage 2 begins.

13-17 June 2022

APRC meeting

16 June 2022

Distributed peer review Stage 2 deadline.

August 2022

Results of the proposal reviews sent to PIs.


Distributed peer review

Here is a quick guide to the basic steps in distributed peer review, from proposal submission to the end of the review process. A complete description of the process can be found here.

  1. Submit a proposal through the ALMA Observing Tool. When submitting the proposal, the PI must designate one member of the proposal team to be a reviewer.
  2. Reviewers should indicate their scientific expertise through their user profile on the ALMA Science Portal by 26 April 2022 15:00 UTC. All efforts will be made by the PHT to assign proposals to reviewers that match their expertise. Click here for more information on the keywords are used by the PHT to assign proposals..
  3. Reviewers have the option to provide a list of investigators for their conflicts of interest through their user profile on the Science Portal. Reviewers need to provide this list by 26 April 2022, 15:00 UTC, at which point the PHT will begin the proposal assignment process. The PHT will not assign proposals to a reviewer in which a PI, co-PI, or co-I is in this list. Click here for more information on conflicts of interest.
  4. The PHT will assign 10 proposals (a ‚ÄúProposal Set‚ÄĚ) to the reviewer on behalf of each proposal in which they are the designated reviewer.
  5. In Stage 1, the reviewers will rank the proposals within a Proposal Set from 1 (strongest) to 10 (weakest), and write a review for each proposal that indicates the strengths and weaknesses. Click here for guidance on writing helpful reviews. Stage 1 is mandatory. Reviewers must submit their reviews by the Stage 1 deadline (01 June 2022 15:00 UTC) or the proposal for which they were identified as the designated reviewer will be rejected.
  6. In Stage 2, reviewers can read the anonymized comments from the other reviewers and update their own ranks and reviews as needed. Stage 2 is optional; no proposals will be disqualified if their designated reviewer does not submit Stage 2 ranks and reviews by the Stage 2 deadline (16 June 2022 15:00 UTC). If a reviewer does not submit the Stage 2 ranks and reviews, then the Stage 1 ranks and reviews will be considered final.


ALMA Proposal Review Committee

Stage 1

The PHT assigns each Large Program a Primary Assessor, who is responsible for leading the proposal discussion and writing the consensus report that will be sent to the PI. All other panel members are assigned Secondary Assessors, barring conflict of interest.

Internal Science Assessors review their assigned proposals, provide a numerical score, and write comments summarizing the strengths and weaknesses of the proposal.

External Science Assessors review a small number (1-3) of Large Programs in their area of expertise, and provide a written report with their reviews.


Stage 2

All internal Science Assessors read the reports of the external Science Assessors in preparation for the meeting. The APRC discusses the proposals and recommends which Large Programs should be scheduled. The Primary Assessors write consensus reports to reflect the final scientific assessment.