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Directors Discretionary Time (DDT)

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Open to proposals from astronomers worldwide, a fraction of the observing time on both Gemini North and South telescopes is reserved for Director's Discretionary Time (DDT).

Evaluation Criteria

The primary consideration in the evaluation of these proposals is likely impact of scientific results. Proposals with a potential for high reward, even if risky, are welcome. DDT can also be requested for small amounts of observing time to test the feasibility of a technique or program, or to respond to an unexpected astronomical event. Note that proposals for Target of Opportunity (ToO) observations, i.e. targets that cannot be specified in advance but which have a well-defined scientific aim and an external trigger, should normally be made via the semesterly proposal process. This is generally the case for e.g. SNe, GRBs, and other classes of targets found as part of surveys or monitoring. However, DDT proposals may request ToO status if the science goal of the proposal justifies it. 

Proposers should provide a very clear and concise scientific justification. They should also describe their strategy for data reduction and fast publication of the results in a high-impact refereed journal.  DDT proposals are judged on the following criteria:

  • Chance of yielding a high-impact result
  • Level of reward, if a "speculative" proposal
  • Uniqueness: must not duplicate current approved observations
  • Urgency (scientific impact to justify not waiting to submit through the regular proposal cycle)
  • Ability of proposing team to make quick use of the data
  • Feasibility, given the current queue.

Submitting a Proposal

DDT proposals may be submitted at any time using the Gemini Phase I Tool for the current semester (e.g., all DDT proposals for semester 2016B must be submitted using the 2016B PIT). Make sure to use the appropriate version to use, as this changes throughout the year.

Before submitting,

  • select "Director's Time" from the Proposal Type menu in the Time Requests tab, 
  • enter the time requested and
  • click "Submit this Proposal" in the Submit tab.

Only proposals submitted this way will be seen and reviewed by the relevant staff (the Gemini Directors and Heads of Science Operations). Technical assessments will be done by Gemini staff where necessary.

For particularly time-critical proposals, proposals will be reviewed within 1-2 working days.  Otherwise, proposals will be reviewed within 5 days. If approved, the program may be on sky within 3 working days after submitting, but this is not guaranteed. Note that the regular semester-based Target of Opportunity process is the most effective way to obtain observations rapidly following a defined trigger.

Projects may be placed in Band 1 or Band 2. PIs do not need to request one or other band. Once validated, approved and ranked, proposals will be prepared using the Phase II (Observing) Tool to be included and activated in the Observing Data Base (ODB) for their execution in the queue.

Note: Within two months following the observations, the PI of an executed DDT program must submit a report on the achieved science and on the status of the publication process to the Gemini Chief Scientist.

Competitive Targets of Opportunity

PIs sumbitting a DD proposal to follow up an exciting transient (for example) should be aware that there may be Queue ToO programs already active which will trigger on the same target. In such cases, there are both specific approval, and specific data access, policies, as detailed on the  Competitive ToO Policies page.

Directors Discretionary Time (DDT) | Gemini Observatory


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