Science Highlight




DDT proposals

The ALMA Observatory is accepting proposals for Director’s Discretionary Time (DDT).

Up to 5% of the observing time in a Cycle can be allocated by the ALMA Director though Director’s Discretionary Time (DDT). They must be submitted using a Cycle 9 specific Observing Tool, available through the links below. The DDT proposals must belong to one of the following categories:

DDT proposals must belong to one of the following categories:

  • Proposals of Target-of-Opportunity (ToO) nature that require the immediate observation of an¬†unanticipated, short-lived astronomical event
  • Proposals that urgently require ALMA observations that could lead to a breakthrough discovery.
  • Proposals of a risky nature that could have a large impact and need a small amount of time to test the¬†feasibility of a program.

The science case of DDT proposals must include a clear and strong justification stating why the project should be considered for DDT allocation. The proposal must also indicate why it was not submitted in the most recent main or supplemental calls.  Proposals that were previously submitted for this cycle but not accepted will typically not be considered for DDT. DDT proposals also cannot duplicate observations in the observing queue.

The science assessment of DDT proposals will be based on the same criteria as for Regular and Target of Opportunity proposals (see the Cycle 9 ALMA Proposer's Guide). DDT proposals will also be evaluated based on the urgency of the observations and why the proposal cannot wait to be submitted at the next regular proposal cycle.

DDT proposals must be submitted using the Observing Tool available through the¬†links below. Preparation and submission of DDT proposals must be done in the same manner as for regular proposals as described in Section 5 of the Cycle 9 ALMA¬†Proposer's Guide. Proposal type ‚ÄúTarget of Opportunity‚Ä̬†should be selected for proposals falling into DDT category 1 above and type ‚ÄúRegular‚ÄĚ should be used for¬†categories 2 and 3.

DDT proposals are reviewed by a small standing review committee, with members from the JAO as appointed by the ALMA Director and the four regions, appointed by the Executive Directors and Chile. The ALMA Director will render a decision based on the advice from the standing committee. Decisions are usually announced within 2 weeks of proposal submission. In exceptional cases, the ALMA Director may approve projects that would benefit from a very rapid response and inform the standing committee of this decision within 24 hours. 

Accepted DDT proposals will remain in observing queue for up to one year. The proprietary period of data obtained for DDT projects is 6 months.


The ALMA Observing Tool (OT) is a Java desktop application used for the preparation and submission of ALMA Phase 1 proposals and, for those which are accepted, Phase 2 materials (Scheduling Blocks). It is also used for preparing and submitting Director's Discretionary Time (DDT) proposals. The current Cycle 9 release of the OT is configured for the present capabilities of ALMA as described in the Cycle 9 Call For Proposals. Note that in order to submit proposals you will have to register with the ALMA Science Portal beforehand.

Download & Installation

The OT should run on all common operating systems and depends on a version of Java being available. In previous releases of the OT it was the responsibility of the user to ensure that a suitable version of Java was installed, but the Cycle 9 version of the OT will come with its own version of Java 11 and thus the user need no longer worry about their local Java installation. Unfortunately, as Java 11 does not include Web Start, this version of the OT is no longer available. The Cycle 9 OT can be installed in two different ways, either with a modern installer or manually with a tarball distribution.

It is recommended that the OT be installed using the ALMA OT Installer. This uses a modern graphical interface to report the progress of the installation and allows the user to change various settings from their defaults, including the amount of memory the OT may use. The installation will produce an executable file that can be used to start the OT. With the loss of Web Start, automatic updates of the tool are no longer possible, but the OT will detect if an update is available at start-up and inform the user. If problems are encountered with the installer, then the tarball must be used. The first release of the OT Installer in 2020 would not run on macOS Catalina due to security issues, but these have now been resolved and it should run correctly on all macOS releases, including Catalina and Big Sur.

The tarball version must be installed manually and the instructions for doing this have not changed.


installer_button tarball_button


Extensive documentation is available to help you work with the OT and optimally prepare your proposal:

  • If you are a novice OT user you should start with the¬†OT Quickstart Guide, which takes you through the basic steps of ALMA proposal preparation.
  • Audio-visual illustrations of different aspects of the OT can be found in the¬†OT video tutorials. These are recommended for novices and advanced users alike.
  • More in-depth information on the OT can be found in the¬†User Manual, while concise explanations of all fields and menu items in the OT are given in the¬†Reference Manual. These two documents are also available within the OT under the Help menu.



If you have problems with the OT, particularly with installation and/or startup, please see the troubleshooting page. A list of currently known bugs, their status and possible workarounds can be found on the regularly updated known OT Issues page. A further source of information is the OT section of the ALMA Helpdesk Knowledgebase - this contains a number of articles that deal with frequently-asked questions. After exploring these resources, if confusion over some aspect of the OT remains, or if a previously unidentified bug has been uncovered, please file a Helpdesk ticket.