Observing > Prop Eval & Time Alloc

Proposal Evaluation and Time Allocation

Semester News

Proposals to the NRAO for the scientific use of its North American facilities are evaluated on a competitive basis. The key components of the process are as follows:

  • Two proposal submission deadlines each year, on 1 Feb and 1 Aug.
  • One Proposal Submission Tool (PST) for proposals to use of one, or a combination, of the GBT, the VLA, or the VLBA/HSA
  • All proposals are evaluated for scientific merit by eight Science Review Panels (SRPs).
  • All proposals are evaluated for technical feasibility by NRAO staff.
  • A single Time Allocation Committee (TAC) is used to recommend the science program each semester on the basis of the scientific merit and technical feasibility of the proposals.

Since ALMA is an international partnership, it has an independent international proposal review process coordinated by the Joint ALMA Observatory. The NRAO proposal evaluation and time allocation process is largely in parallel to the JAO's, but it is expected that VLA, VLBA and GBT scheduling will be coordinated with that of ALMA to an extent that is practicable, one that will evolve with time and experience.

All proposers are expected to use the NRAO PST via the NRAO Portal (documentation available here) to prepare and submit their proposals. Regular, Large, and Triggered proposals must be submitted on or before the proposal submission deadlines of 1 Feb and 1 Aug each year. Proposers are expected to suggest into which of the eight broad scientific categories their proposal may be placed. A number of tools are available to support proposal planning; e.g., sensitivity and exposure calculators, and a Proposal Finder Tool (PFT) that may be used to search cover sheets of proposals previously approved for time on NRAO telescopes.

Following the proposal submission deadline, proposals are checked to ensure that they are properly categorized and the proposals in each science category are made available to the corresponding SRP. An SRP comprises the Chair and five members. All members are drawn from the scientific community and serve on a volunteer basis. The members review all proposals that fall within the scientific purview of the SRP, typically 50 proposals per semester. The Chair only reviews those proposals on which a panel member is conflicted. The SRP is responsible for producing a rank-order list of proposals based on scientific merit. SRP business is conducted using online proposal management tools and one or two telecons. Each SRP Chair serves on the TAC. The TAC membership is available here. The role of the TAC is to recommend time allocations and scheduling priorities for the VLA, VLBA, and GBT. The TAC has the discretion to allocate limited amounts of time on NASA missions with which the NRAO has joint observing agreements. They also advise the NRAO on policy matters and programmatic issues relevant to the time allocation process.

The final recommendations of the TAC for North American NRAO facilities are reviewed and approved by the Directors' Review, a committee involving the NRAO Director, the Chief Scientist, the Assistant Directors for New Mexico operations and Green Bank operations, the Assistant Director for  Science Support and Research, and NRAO staff relevant to the time allocation process and telescope scheduling.  It is expected that the Directors' Review will aim to follow the recommendations of the TAC.

The time to completion of the proposal evaluation and time allocation process, from the proposal deadline to the time the science program is posted for the semester under evaluation, is nominally 14 weeks. A timeline of the process is available here.

It is also possible to propose for Director's Discretionary Time (DDT). DDT is reserved for Targets of Opportunity and for Exploratory Time. DDT proposals may be submitted at any time. They must be submitted through the PST. DDT proposals are reviewed by Observatory scientific staff on the basis of the proposals' scientific merit and technical feasibility.