What is Director's Discretionary Time (DDT)

Five percent of the available Spitzer observing time is allocated by the SSC Director as Director's Discretionary Time (DDT), and is intended to facilitate observations that address emerging scientific topics or areas missed in the proposal review process. Investigators wishing to request DDT can do so at any time during the year, by using the DDT submission template and procedures described here. Requests for DDT must be submitted electronically to the SSC Director.

The inaugural DDT program was the First Look Survey (FLS), which provided an early and representative sample of reliable infrared data. A portion of the Director's DDT was allocated to observations made by the Spitzer Fellows.

The primary utilization of additional DDT programs is in support of community-proposed requests that are based on exceptional, time-critical observing opportunities that cannot be accommodated with the regular cycle of Calls for Proposals. Other DDT usages include innovative observations that extend the scientific capabilities of Spitzer, and extraordinary events and opportunities that necessitate -- in the view of the SSC Director -- observations to be obtained with Spitzer for the benefit of the astronomical community.

DDT requests must include:

1. a strong scientific justification;
2. a description of the long-term legacy value of the program;
3. completed Astronomical Observation Requests (AORs), if possible;
4. a justification for why the request was not submitted during the Cycle-6 Call for Proposals.

Recognizing the limited lifetimes for major space astronomy facilities, such as the Hubble Space Telescope, the Chandra X-ray Observatory and Spitzer, DDT proposals for rapid follow-up of new discoveries will also be considered. In such cases, the proposing investigator must demonstrate that the observations will provide a critical link in the understanding of the phenomena and that carrying them out quickly is particularly important for planning future observations with major facilities. They should then also indicate their plans for quickly making the scientific community aware of their discoveries, to enable subsequent wider community follow-up.

A request for DDT observations is predicated on the assumption that the proposed observations are urgent, and that the observations will be of interest to the broad scientific community. Therefore, data validation periods for DDT observations will be no more than three months, at which point the data will enter the public domain. The SSC Director reserves the right to make all raw and calibrated data publicly available immediately as a condition for approving a DDT request, particularly where the data involve an unexpected Target of Opportunity.

Any science data analysis funding awarded to successful DDT proposers is determined using the same formula utilized for funding the current GO cycle.

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