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DDT proposals

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

DDT observations during Cycle 4 will be conducted on a best effort basis, with priority given to the completion of the full ALMA capabilities.

DDT proposals may be submitted at any time during Cycle 4, for implementation during this cycle. They must be submitted using a Cycle 4 specific Observing Tool, available through the link 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 4 proposals – see the ALMA Cycle 4 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 4 proposals: see Sect. 6 of the ALMA Cycle 4 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 4 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 5 process, for which a call for proposals is expected to be issued in 2017.

Cycle 4 policies are fully applicable to DDT proposals; in particular, DDT observations will be executed using the Cycle 4 capabilities and observing restrictions, as described in the ALMA Cycle 4 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 4 specified above). The science assessment of DDT proposals will be based on the same criteria as for standard and ToO proposals (see Sect. 4.2 of the ALMA Cycle 4 Proposer's Guide).

Given the limited amount of time available in Cycle 4 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 4, 150 hours on the 12-m Array and 90 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 4 OT Download & Installation

The OT will run on most common operating systems, as long as you have Java 8 installed (see the troubleshooting page if you are experiencing Java problems). The ALMA OT is available in two flavors: 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. There are some issues with Web Start, particularly that it does not work with the Open JDK versions of Java such as the "Iced Tea" flavor common on many modern Linux installations. The Sun/Oracle variant of Java should therefore be installed instead. 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, however there should be no installation issues. For Linux users, we also provide a download complete with a recommended version of the Java Runtime Environment. Please use this if you have any problems running the OT tarball install with your default Java.



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

  • OT QuickStart Guide is a good starting point for novice OT users. The guide takes you through the basic steps of ALMA proposal preparation.
  • OT video tutorials provides audio-visual illustrations of different aspects of the OT. The video tutorials are recommended for novices and advanced users alike.
  • User Manual provides in-depth information on the OT.
  • Reference Manual provides more concise explanations of all fields and menu items in the OT. 



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 4 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 4 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-CycleXXX/setup 
    cd ..

  • MS Windows

-> Go to the ALMAOT-CycleXXX/setup directory

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

-> Go to the ALMAOT-CycleXXX directory

4. Start up the OT

  • Linux or Mac OS:


  • MS Windows

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