The Green Bank Telescope

General Proposal Information

Information on requirements for submitting GBT proposals along with the review and scheduling process are summarized under the following topics.

Proposal Deadlines and Types of Submissions

The GBT proposal deadlines are the same as the NRAO VLA and VLBA deadlines,  namely February 1,  June 1, and October 1of each year.  Each proposal deadline accepts proposals for scheduling in the next trimester.  The year is broken into trimesters beginning with February 1 of the year.  For example, the first trimester is formally the period from February 1 through May 31 (see Trimester and Proposal Code Nomenclature below for nomenclature) and normally proposals accepted from the Oct 1 deadline (the one previous to the Feb 1 date) would be scheduled during  this four month period.  Any proposals that have been approved and  cannot be scheduled in the next trimester will be held and scheduled at the next available opportunity.  Any proposal rejected from a particular deadline must be re-submitted at the next deadline to be considered for a future trimester.

Effective October 1, 2003 NRAO proposal submissions will be considered either a regular submission or a Rapid Response Science submission. Rapid Response Science falls into three categories:

  1. Known Transient Phenomena (KTP) - These proposals will request time to observe phenomena that are predictable in general, but not in specific detail. For example, a proposal to observe the next flaring X-ray binary that meets certain criteria would be included in this category. These proposals are to be submitted during one of the regular calls for proposals and peer reviewed along with all regularly submitted proposals.
  2. Exploratory Time (ET) - These proposals are for small amounts of time, typically a few hours or less, in response to a recent discovery, possibly to facilitate future submission of a larger proposal. For example an exciting new pulsar may be discovered at another telescope and it may be desirable to confirm the detection before committing or proposing for a much larger amount of observing time. All of these proposals are reviewed by the GBT Proposal Selection Committee and a decision is usually made within 1-2 weeks.
  3. Target of Opportunity (ToO) - These proposals are for true targets of opportunity--unexpected or unpredicted phenomena such as supernovae in nearby galaxies. All of these proposals are reviewed by the GBT Proposal Selection Committee and a decision is usually made within 1-2 weeks.

See the link at Rapid Response Science for a full description of the requirements and proprietary periods. Rapid Response Science requests of type 1 (Known Transient Phenomena) must be submitted during the regular trimester call for proposals. Rapid Response Science requests of type 2 (Exploratory Time) and type 3 (Target of Opportunity) can be submitted at any time. The new NRAO Proposal Submission Tool must be used for any type of Rapid Response Science requests (see NRAO Proposal Submission Tool Cookbook for the details).

 

Trimester and Proposal Code Nomenclature

Proposal documentation, statistical information and proposal codes all reference specific trimesters by a code of the following form nnX where nn is the last two digits of the year and X is one of A, B or C.  A, B and C refer to the first, second and third trimester of the year respectively.   In particular A denotes February 1 through May 31, B denotes June 1 through Sep 30 and C denotes Oct 1 through Jan 31. 

GBT Proposal codes take on the format, GBTnnX-NNN, where nnX is the trimester code and NNN is a sequentially assigned number for the particular proposal deadline.
 

Proposal Submission Policies

GBT proposals are submitted using a software program called the GBT Proposal Submission Tool. An overview of the use of this tool for submitting proposals can be found at the link GBT Proposal Submission Tool Cookbook. Important points to remember:

  • All proposals must be submitted using the NRAO Proposal Submission Tool . This includes all forms of Rapid Response Science requests. See GBT Proposal Submission Tool Cookbook for a discussion of how to submit Rapid Response Science Requests.

  • The title is limited to 80 characters. Scientific and technical justification is limited to four pages. Only one attachment is allowed.

  • Proposal requesting use of the GBT for VLBI (including VLBA) experiments must NOT be submitted using the NRAO Proposal Submission tool but must be submitted through the normal VLBA/VLBI submission  process.

  • Deadline for acceptance of the proposal will vary with the particular trimester (it is normally the first day of the fourth month preceding the trimester observing dates).  For example the deadline for submitting proposals for the A trimester (observing period Feb 1 - May 31) will normally be the preceding October 1. The specific deadline will be published in each Call for Proposals announcement, which will be published approximately one month before the deadline.
     
  • Note that only black and white figures will be sent to the referees. Any color figures submitted will be reproduced as black and white.

  • Any proposal which requests use of GBT for short spacings with VLA observations must submit separate GBT and VLA proposals. The GBT proposal should specifically state at the end of the abstract that this is a combined GBT and VLA submission.

Proposal Evaluation Process

A very brief outline of the steps followed at the close of each proposal deadline is described in chronological order.

  1. Immediately upon the close of the deadline (a) basic proposal information is transferred to a database, (b) hard copies are made of all proposals received and (c) a very cursory check is made for any obvious omissions or gross errors.
     
  2. All proposals are assigned to referees based on scientific expertise of the referees and the details of each proposal. All referees are external reviewers, i.e. outside NRAO.  Every attempt is made to assign five referees to each proposal. Copies of the appropriate proposals are sent by FedEx overnight to each of the referees. (1) and (2) take about 1-2 weeks.
     
  3. Proposals may also be distributed to GBT scientific staff for a technical evaluation.  This evaluation checks that the equipment and observing mode requests are feasible and optimal, and that integration times are accurate.
     
  4. Within 1 to 2 days of sending the proposal copies to the referees, instructions along with a template to be used for their reviews are emailed to each of the referees. The referees are asked to supply a review for each proposal that includes:
    5.  
    • A rating based on scientific merit. Beginning with the 04B trimester the suggested scale is 1 (outstanding) to 9 (reject) where qualitatively 9=poor, 5=average, 3=good, 2=excellent and 1=outstanding. Prior to trimester 04B the rating scheme went from 1 (reject) to 5 (outstanding).
    • A recommended percentage of requested time.
    • Overall comments on strengths, weaknesses, omissions, or errors, etc., on arriving at the rating.

    The referees are given a deadline to return their reviews The time between sending out the email template and the receipt of all the reviews is usually about 1 to 1.5 months.
     

  5.  Once all referee reviews have been received, a brief check for completeness of the reviews is made and the review details are transferred to a database. Reports are prepared for the Scheduling committee.

    6.  
  6. The Scheduling Committee meets about two weeks after all reviews have been received. Proposals are ranked by a weighted average of the ratings. The ratings are weighted using the individual referee averages and rms.

    The Committee groups all proposals into three categories or groups based on referee ratings.

    • Group A proposals are chosen from the highest ranked to fill the available observing time for the particular trimester. These proposals are generally assured of telescope time. New beginning with trimester 08C: However, unless otherwise stated in the email disposition notice, proposals will be considered active only for up to a limit of three consecutive trimesters (in practical terms this might be only 2 for some high frequency proposals) starting with the trimester they have been approved for. If the proposal has not been scheduled after this time period it will be closed and the investigators will have to re-submit if they still want to be considered.

    • Group B proposals are provisionally accepted with no allotment of observing time beginning in trimester 04C. These proposals will be kept open for one trimester only and if they cannot be assigned time that term, they will be dropped from the queue and the proposer notified. The GBT is scheduled dynamically according to the weather, and the number of proposals selected each term is based on statistical norms for weather conditions. The Group B proposals allow for variations of weather from the norm. For example, if the trimester has higher water vapor conditions than normal, there may be more low frequency time available, and some of the low frequency Class B proposals may be scheduled. Conversely, if weather conditions are better than normal, some of the high frequency proposals in Class B might be scheduled. Since Class B proposals are at the mercy of the weather and there is no guarantee of time, proposers who wish to improve their chances of scheduling may wish to revise and resubmit their proposals at the next deadline. If the initial Class B proposal is ultimately scheduled, the resubmitted proposal can be withdrawn. Proposals prior to 04C with a group B designation were guaranteed the time allotted to them.
      Beginning in trimester 9C, Group B proposals can be assigned as B+, B or B-. A B+ proposal will receive a higher likelyhood of being scheduled by the Dynamic Scheduling Software (DSS) than a B proposal. Likewise a B- proposal will be less likely to receive time than a B proposal.

    • Group C proposals are the lowest ranked by the referees or may have a technical problem that renders them infeasible or there is no available time remaining in the trimester. They are awarded no observing time and are being dropped from the queue. Proposers who wish to pursue the project should revise and resubmit the proposal.

    • Group H proposals will be held over for consideration in the next appropriate trimester (and Call for Proposals). They are awarded no observing time for the current or future trimesters. They will carry over their rating to the appropriate future calls and be considered and ranked along with the new proposals using the current ranking. This will allow the proposers the opportunity to revise and resubmit the proposal if they desire.


    Although the Committee primarily follows the referee ratings for assignment of telescope time, an attempt is made to take into consideration unusual or extenuating circumstances arising in the review process such as instrument limitations or possible referee misunderstandings, and conflicts with other proposals.
     
  7. After the deliberations of the Scheduling Committee all proposal investigators are notified of the status of their proposals by email. This usually occurs about a week following the meeting
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  8. All proposals that have been granted observing time are placed into a queue for scheduling consideration (see Scheduling Process)
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Last updated 18 August 2009 by Toney Minter