Director's Discretionary Time

Proposals for Director's Discretionary Time (DDT) may be submitted at any time. They must be submitted through the PST. DDT proposals are intended to address targets of opportunity, high-risk/high-return exploratory time, or other science opportunities deemed sufficiently urgent to justify prompt action.

IMPORTANT: The Science Justification for a DDT proposal is limited to two (2) pages.

DDT proposals may also be submitted for the purpose of education and public outreach - for example, to image an iconic source or to support a educational opportunity for students. Such proposals should clearly justify the requirements for the requested time allocation and observing mode on any given instrument, and should describe the anticipated impact of the observation.   For the VLA, the list of active triggered proposals can be consulted to determine whether there is an active conflicting proposal.

While there is not an a priori limit to time that can be requested via DDT, it is expected that no more than 5% of the observing time on each telescope will be allocated for this purpose.

DDT proposals are reviewed by Observatory scientific staff on the basis of the proposals' scientific merit and technical feasibility. These reviews adhere to Observatory policy regarding non-disclosure and conflicts of interest. If a DDT proposal is declined, a brief justification is provided to the proposing team by the relevant Site Director's office. If a DDT proposal is approved, then the relevant Site Director's office, in consultation with the NRAO Director or his/her designee, will assign a proprietary period for the data based on scientific and programmatic considerations.

If a DDT proposal is approved, the Proposal Finder Tool (PFT) will have access to its authors, title, abstract, and approved hours.  The approved DDT proposals can be listed by using the DDT filter under Type.  Also see the Approved DDT Proposal page.  Use the Archive Access Tool (AAT) to check if a specific DDT proposal has been observed and to access the data.

N.B., DDT proposals cannot be joint proposals that request external telescope time.  For example, a DDT proposal cannot request HST orbits.

For NRAO policy on conflicts between DDT and non-DDT proposals, see here.  Also see the VLA  list of active triggered proposals for possible conflicts.

Connect with NRAO

The National Radio Astronomy Observatory and Green Bank Observatory are facilities of the U.S. National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

Founded in 1956, the NRAO provides state-of-the-art radio telescope facilities for use by the international scientific community. NRAO telescopes are open to all astronomers regardless of institutional or national affiliation. Observing time on NRAO telescopes is available on a competitive basis to qualified scientists after evaluation of research proposals on the basis of scientific merit, the capability of the instruments to do the work, and the availability of the telescope during the requested time. NRAO also provides both formal and informal programs in education and public outreach for teachers, students, the general public, and the media.

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