Science Highlight




ToO activation

General Description of Target of Opportunity (ToO) Observations 

  • Certain classes of astronomical transient events occur at frequent and unpredictable intervals (e.g. gamma ray bursts). Investigators wishing to study such events as a class are required to submit proposals at the time of regular proposal submission.


Procedure of ALMA Target of Opportunity Project

Preparing Target of Opportunity Observations

  • ToO proposals should be used to observe targets that can be anticipated but not specified in detail. Like standard proposals, these proposals must be submitted by the regular proposal deadline. While the target list may be left unspecified, observing modes and sensitivity requests must be specified in detail for ToO observations. Associated with these observations there must be a clear indication of the number of triggers needed to reach the science goals of the proposal, what triggers the actual observation to be performed and the maximum response time for scheduling the observation after it is triggered.


After approval of your Target of Opportunity Project

  • You are assigned a contact scientist who interacts with you in the creation of the relevant Phase 2 Scheduling Blocks (SBs). In this process, you should approve the final Phase 2 SB with basic instrumental setting.


Trigger your ToO observations

  • Triggering of observations from accepted ToO proposals must be done through the ALMA HelpDesk. When a qualifying event occurs, the PI (or an assigned delegate) must submit a request for observation (i.e. trigger) through the dedicated page on the HelpDesk. The trigger will be monitored on a daily basis by the Astronomer-on-Duty (AoD) at the OSF.
  • First, the PI (or delegate) should go to the HelpDesk and enter your ALMA User ID and password. Once you are logged into the HelpDesk, the “Trigger your Project” option will be visible on the main page. Please follow this link and fill out the information required. Each trigger must specify which SB to execute and the corresponding target coordinates (and velocity). In addition, the PI (or delegate) should specify the maximum response time compatible with achieving the scientific goal(s) of the project.
      • You will not be able to select the project you wish to trigger if you are not logged into the HelpDesk with the same account that is the PI of the project, or an assigned delegate
  • When a trigger is received, an automatic acknowledgment from the HelpDesk will be emailed to the PI and the AoD will enter the provided target coordinates into the specific SB and execute the SB as soon as possible after the PI's confirmation.
  • The PI (or delegate) can follow the link in the email notification or look under “My Tickets” on the HelpDesk to communicate with the AoD through the HelpDesk ticket.
  • Depending on the exact timing of a ToO observation trigger, the reaction time for its execution may be as long as 2 weeks.


ToO data access

For ToO observations that require follow up/subsequent observations based on the outcome of the initial observation, PIs (or assigned delegates) have the possibility to request the release of the raw data via the Helpdesk to enable a prompt analysis. The proprietary period for these observations will start when the quality assured data products are delivered to the PI, as for any other observation. See the ALMA User's Policies for further information on the proprietary period.



  • Only observations within the context of the ToO proposal will be performed. Requests beyond the scope of the ToO proposal will not be accepted.