Director’s Discretionary Time

DDT may be requested at any time and is appropriate for the following cases:

  • Target of Opportunity (ToO) proposals are for unexpected or unpredicted phenomena such as, but not limited to, extreme X-ray or radio flares. ToO proposals are evaluated rapidly, with scheduling done as quickly as possible and as warranted by the nature of the transient phenomenon.
  • Exploratory Time proposals are normally for requests of small amounts of time, typically a few hours or less, in response to a recent discovery, possibly to facilitate a future submission of a larger proposal. In general, there will not be a need for immediate scheduling with these proposals but, for example, they may need to be observed in the current VLA configuration rather than waiting 16 months.
  • Proposals may 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. These proposals must involve the Observatory’s Education and Public Outreach program.
  • Proposals for other science opportunities deemed sufficiently urgent to justify prompt action.
  • Proposals may be submitted in response to a Special Call announced by the Observatory. The announcement for the Special Call is available online at https://science.nrao.edu/observing/call-for-proposals.

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 Open Skies time on each facility will be allocated for this purpose. DDT proposals cannot be joint proposals that request external telescope time; however, joint proposals between the Observatory’s facilities are allowed. For example, a DDT proposal cannot request HST orbits, but a DDT proposal can request joint observations with the VLA and VLBA.

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.

The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 "to promote the progress of science; to advance the national health, prosperity, and welfare; to secure the national defense..."

AUI collaborates with the scientific community and research sponsors to plan, build, and operate cutting-edge facilities. We cultivate excellence, deliver value, enhance education, and engage the public.