JWST Target of Opportunity Roadmap

A step-by-step guide through the process of designing a target of opportunity program with JWST is provided in this article.

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Preliminary considerations

A target of opportunity program is a special case because the details of targets and/or observations cannot be specified explicitly at the time of the initial proposal. The target could be a known target that may have an outburst at an unknown time or be a class of target (a supernova or a GRB) whose position and other information is not known until the triggering event occurs. The  descriptive PDF file you attach to the proposal for submission is very important for ToO programs and needs to provide the details. This description should also clearly describe what the trigger mechanism will be for activating the ToO program.

  1. Review the policies and properties of JWST ToO programs and their activation in these articles:
    Target of Opportunity Observations (in the Call for Proposals material)
    JWST Target of Opportunity Observations (provides additional background)
    JWST Target of Opportunity Program Activation

  2. Understand the range of expected target fluxes or magnitudes for your potential targets in the wavelength range of interest.

Proposing for ToOs

  1. Choose the instrument(s) suitable for your science.  Understand what filters or gratings are needed and any other instrumental set-up information.

  2. Use the ETC to determine the exposure parameters necessary to observe your target(s) when the ToO activates, and for any follow-up observations.  For objects with an expected range of potential flux levels, you may want to evaluate both a best case and worst case to understand the range of potential resources needed.
    JWST Exposure Time Calculator Overview

  3. Enter your target(s) into APT.  Known targets that might go into outburst at an unknown time can be entered as regular fixed targets.  Unknown targets (say a supernova brighter than some magnitude or a GRB) should be entered as generic targets.
    APT Targets

  4. Fill out representative observing templates for each instrument and mode that you are proposing to use.  For help, select the appropriate template from this listing:
    JWST APT Observation Templates

    4a. In addition to entering your observation specifications, on each listed observation, you should open the Special Requirements tab and select “Target of Opportunity.”  APT will pop-up a box for you to enter the requested turnaround time. Note: turnaround times <14 days are potentially disruptive to scheduling and are a limited resource of the observatory. Turnaround times < 3 days are termed ultra-disruptive and are extremely limited. See JWST Target of Opportunity Observations for more information.
    JWST Target of Opportunity Program Activation

    4b. An “On Hold” special requirement will be generated automatically as well, and you will need to enter a comment.

  5. Estimate the total resources your proposal will require if accepted and activated. APT will report numbers based on whatever you enter into templates, but it cannot take into account aspects that may only be described in your PDF. 
    For example, perhaps you entered a single NIRSpec fixed slit observation into APT, but expect to execute it four times at some interval after the trigger, to watch the source fade.  You could take the resource estimate APT makes for the single observation and estimate the total resource needed, assuming longer exposure times as the ToO fades.

  6. The Proposal Information page in APT contains a box labeled “Request custom time allocation” which should be selected, and appropriate comments entered in the resulting pop-up window.  Your assumptions should be described in detail in your Description of Observations section of your PDF attachment.

  7. Finalize and attach your science PDF proposal, including science justification, description of observations, the triggering information, and the speed with which the trigger needs to be reacted to. 

  8. When completed, use the submission tool in APT to submit your program.  If any errors or warnings remain, explain them in the pop-up box provided at the time of submission.
    APT Submitting Your JWST Proposal

Activating ToOs

  1. When a potential trigger for a given ToO target occurs, use the General Target Visibility Tool to  assess its visibility for JWST observations.
    JWST General Target Visibility Tool Help

    Note: if your science involves a sequence of observations following the initial trigger and observation, verify not only that the target is observable, but that it will remain visible for the desired period of the follow-up observations.

  2. Once you are convinced you are ready to trigger the ToO, contact the Program Coordinator who was assigned to your program at the time of acceptance.  Refer to your acceptance letter.

Notable updates

Minor text and link updates.

Originally published