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DDT proposals

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

DDT proposals may be submitted at any time during Cycle 6, for implementation during this cycle. They must be submitted using a Cycle 6 specific Observing Tool, available through the links below. The DDT proposals must belong to one of the following categories:

  1. Proposals requiring the immediate observation of a sudden and unexpected astronomical event (“immediate” should be understood as within a period of 3 weeks following their approval: the same time tolerance restriction applies to DDT proposals as to standard and ToO Cycle 6 proposals – see the ALMA Cycle 6 Proposer's Guide for details);
  2. Proposals requesting observations on a highly competitive scientific topic, motivated by developments that have taken place after the regular proposal submission deadline;
  3. Proposals asking for follow-up observations of a program recently conducted with ALMA or any other observing facility, where a quick implementation is expected to provide breakthrough results.


Preparation and submission of DDT proposals must be done in the same way as for regular Cycle 6 proposals: see Section 5 of the ALMA Cycle 6 Proposer's Guide for details. Note that proposal type “Target of Opportunity” should be selected for proposals falling into DDT category 1 above, and type “Standard” used for categories 2 and 3. In addition, the science case of DDT proposals must include a clear and strong justification stating why the project should be considered for DDT allocation and why it was not submitted as part of the regular Cycle 6 process. In the absence of such a justification, the proposal will not be considered for DDT allocation, and the proposers will be encouraged to resubmit it as part of the regular Cycle 7 process, for which a call for proposals will be issued on March 19, 2019.

Cycle 6 policies are fully applicable to DDT proposals; in particular, DDT observations will be executed using the Cycle 6 capabilities and observing restrictions, as described in the ALMA Cycle 6 Proposer's Guide and documents referenced therein. However, the proprietary period of data obtained as part of DDT projects will be restricted to 6 months.

DDT proposals will be approved for execution by the ALMA Director, based on the advice of a small standing review committee, with members from the JAO and the four regions, appointed by the Executive Directors and Chile. 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 (but note the 3-week time tolerance restriction for Cycle 6 specified above). The science assessment of DDT proposals will be based on the same criteria as for standard and ToO proposals (see Section 3.5 of the ALMA Cycle 6 Proposer's Guide).

Given the limited amount of time available in Cycle 6 and the heavy oversubscription of this time by standard proposals, DDT proposals may be approved only if their science case is exceptionally strong, especially if they are not related to the observation of a sudden and unexpected astronomical event.

In Cycle 6, 200 hours on the 12-m Array and 150 hours on the ACA will be available for DDT proposals.

Approved DDT proposals will be added in a separate table to the published list of High Priority projects for each cycle.



Cycle 6 OT Download & Installation

The OT will run on most common operating systems, as long as a 64-bit version of Oracle Java 8 is installed (see the troubleshooting page if you are experiencing Java problems). The OT may work with higher versions of Java, but this cannot be guaranteed. The ALMA OT is available in two flavours: Web Start and tarball.

The Web Start application is the recommended way of using the OT. It has the advantage that the OT is automatically downloaded and installed on your computer and it will also automatically detect and install updates. However, Web Start has been removed from Java 11 and bugs were present in Java 9 (and maybe 10). If this is not possible, then the tarball installation of the OT is available.

The tarball version must be installed manually and will not automatically update itself, although it will indicate if an OT update is available for download. It is in general though less prone to installation problems than Web Start.

button_webstart button_tarball


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 installation and/or startup of the OT, 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.



OT Cycle 6 Web Start download:


Click logo to start.

Click the OT Logo to start the OT. If the OT has not been downloaded before, or if an update has been released, a download window will appear. For first-time users, after the download has completed, you may (depending on your operating system) be given the option to create a shortcut, or one will be created automatically for you, usually on the desktop. Future use of the OT can then most conveniently be started by double-clicking the shortcut. Even if a shortcut is not created, the OT will have been downloaded into the Web Start cache and can be started from the Java Cache Viewer (accessible using 'javaws -viewer' or from Java Preferences on a Mac).


  • The Web Start will automatically detect if an update to the installed version of the OT has been released and will automatically download it.
  • If a network connection is not available, the Web Start version will still work, but will obviously not be able to update itself or use the OT's external services such as the user database, online spectral line search, etc.



OT Cycle 6 Tarball download:


The tarball version of the OT is not the recommended way of using the OT and should usually only be used if it proves impossible to get the Web Start version working. The installation instructions for the tarball version are:

1. Download the tarball in your preferred format:


2. Unpack the tarball (it will unpack into its own directory).

3. Run post-installation setup

  • Linux or Mac OS:

    cd ALMAOT-Cycle*/setup
    cd ..

  • MS Windows

-> Go to the ALMAOT-Cycle*/setup directory

-> Double click "Setup-Windows" (may read "Setup-Windows.cmd")

4. Start up the OT

  • Linux or Mac OS:


  • MS Windows

Double-click "ALMA-OT" (might read "ALMA-OT.cmd")


Note: Due to licencing issues, it is no longer possible to offer a version of the OT that comes with its own version of Java.