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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.
Directors Discretionary Time (DDT) | Gemini Observatory


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