TAC Guidelines

Overview

The NRAO/GBO Telescope Time Allocation Committee (TAC) comprises the Chairs of the Science Review Panels (SRPs). The SRP Chairs will be quite familiar with the proposals that fall under their particular science category when they meet as the TAC. They should also be familiar with the large proposals as well as certain other proposals that may be identified by the NRAO/GBO or TAC members.

The purpose of the TAC meeting is not to re-review proposals. The SRP members, individually and collectively, have thoroughly evaluated the proposals and have produced rank-ordered lists for each science category based on scientific merit. The TAC will not re-visit the scientific merit of a given proposal. However, they will, as a group, be called upon to weigh the relative merits of different proposals in light of technical, scheduling, and programmatic constraints.

The primary task of the TAC is to consider the merged list of rank-ordered proposals and to make recommendations regarding time allocation and scheduling priority for each proposal. This document provides guidelines for this process.

 

TAC Procedures and Workflow

The deliberations of the TAC will be split into two meetings: (1) a large proposal meeting where only proposals of type "large" will be considered; and (2) a regular proposal meeting where the remaining proposals, those of type "regular" and "triggered", will be considered.  The large proposal meeting will be held remotely, whereas the regular proposal meeting will be hybrid.  During the TAC's large proposal meeting, the TAC Chair will coordinate the workflow. The order of consideration of the large proposals will be circulated in advance. During the TAC's regular proposal meeting, regular and triggered proposals will typically be considered in the following telescope order: GBT, then VLA, VLBA, and HSA/GMVA. An agenda for the regular proposal meeting will be circulated in advance.

Before the TAC considers a given telescope’s proposals, NRAO/GBO will provide a summary assessment of the scheduling and programmatic constraints relevant to that telescope. Also included will be two documents:

  1. A narrative that summarizes the proposals and any salient issues.  This includes an LST (or GMT) pressure plot with relevant scheduling or weather constraints.
  2. A compact summary of each proposal that includes identifying information and SRP comments. 

There is also a TAC Meeting page in the PST (see the Appendix below), but this tool is not necessary to perform the TAC functions.  Observatory staff will take notes and draft TAC Comments based on the TAC discussions.  The TAC will have the opportunity to modify these comments.  Factors that the TAC should consider in making recommendations regarding a scheduling priority and time allocation for a given proposal are outlined below for each of the proposal types. 

 

Management of Conflicts

Please review the NRAO Conflicts of Interest and Confidentiality Polices here.

 

TAC Consideration of Proposals

The TAC’s primary task is to recommend a scheduling priority and a time allocation for each proposal to the Observatory Director. There are four scheduling priorities:

A: the observations will almost certainly be scheduled

B: the observations will be scheduled on a best-effort basis

C: the observations will be scheduled as filler

N: the observations will not be scheduled

The time allocation reflects the TAC’s judgment regarding the time needed to fulfill all, or part, of a proposal’s science objectives in light of factors such as scheduling constraints, operational considerations, the adjudication of source conflicts, proposal pressure as a function of LST, and so on.

Preliminary scheduling priorities are provided for each session in each proposal. The preliminary scheduling priority factors in operational constraints and proposal pressure. However, the TAC may wish to change a scheduling priority if it believes the science objectives of the proposal are better served by doing so and/or if it believes the science impact will be enhanced by doing so. The TAC must be aware, however, that a change in scheduling priority has a ripple effect: if a B priority is changed to A, then session(s) currently at A priority will need to be demoted to B or C in order to accommodate the change.

In reviewing the proposals as a whole, and in making its recommendations, the TAC is in a position to see the entire science program proposed for a semester. The TAC should feel free to comment on its impressions about the program. Is it compelling? Exciting? Timely? Should the Observatory institute changes in its proposal calls, review process, time allocation process, and policies to better solicit and enable the science that truly is timely and compelling?

We now comment on factors to consider when discussing and making recommendations for each type of proposal that the Observatory currently receives at its semiannual proposal deadlines: large, regular, and triggered proposals.

Large Proposals

Large proposals are those requesting time allocations of 200 hours or more (N.B., there are some exceptions for the GBT). Given the substantial impact of large proposals on NRAO/GBO operations and resources, we ask that all TAC members read the large proposals in advance of the TAC meeting. The relevant SRPs have ranked all proposals, including large proposals, on the basis of their scientific merit. However, in addition to presenting a science justification, large proposals are required to include a data reduction and data release plan. NRAO policy regarding large proposals may be found at:

https://science.nrao.edu/observing/proposal-types/largeproppolicy

The TAC should therefore take the following factors into consideration when recommending a scheduling priority and time allocation for large proposals:

  • Science ranking: given resource requirements, large proposals should be of high scientific merit.

  • Technical feasibility: are the observations possible with the proposed observing modes and resources? Is the time requested sufficient to achieve the proposed science objectives? Too much? Too little?

  • Scheduling constraints: are the observations possible in light of operational constraints and prior time commitments; are they to be preferred over other proposals at highly over-subscribed LSTs?

  • Data reduction and release plan: does the proposing team have a well-considered plan to reduce and release the data to the community in a timely fashion?

  • Science impact: what is the likely impact of the proposed observations? How broad or how deep?

  • Community impact: does the proposal include significant participation on the part of students and postdocs?

Some proposals may have their total time altered so that they technically go from Regular-->Large or Large-->Regular (e.g., technical review indicated more time is required).   We will not change the proposal type but flag this proposal at the TAC meeting. We will give the TAC the following guidelines: If the proposal goes from Large to Regular then there should be no real issues. But if the proposal goes from Regular to Large then if the TAC really likes the proposal, they would simply be limited to only giving it as much time as is allowed in the regular proposal call (e.g., 200 hours over 1 year). If the TAC feels that is not enough hours to accomplish the science, then the proposal is rejected.

 

Regular Proposals

Regular proposals are those requesting time allocations of less than 200 hours. Regular proposals have been ranked on the basis of their scientific merit by the relevant SRP. The TAC should therefore take the following factors into consideration when recommending a scheduling priority and time allocation for regular proposals:

  • Science ranking: given resource requirements, regular proposals should be of high scientific merit.

  • Technical feasibility: are the observations possible with the proposed observing modes and resources? Is the time requested sufficient to achieve the proposed science objectives? Too much? Too little?

  • Scheduling constraints: are the observations possible in light of operational constraints and prior time commitments; are they to be preferred over other proposals at highly over-subscribed LSTs?

  • Science impact: what is the likely impact of the proposed observations? How broad or how deep?

 

Triggered Proposals

Like regular proposals, triggered proposals request time allocations of less than 200 hours. Unlike regular proposals, observations only occur of a defined type of object when specified triggering criteria are met. Triggered proposals have been ranked on the basis of their scientific merit by the relevant SRP. The TAC should therefore take the following factors into consideration when recommending a scheduling priority and time allocation for triggered proposals:

  • Science ranking: given resource requirements, triggered proposals should be of high scientific merit.

  • Technical feasibility: are the observations possible with the proposed observing modes and resources? Is the time requested sufficient to achieve the proposed science objectives? Too much? Too little?

  • Triggering criteria: are the triggering criteria well-defined? Are the operational impact and consequences well-understood?

  • Science impact: what is the likely impact of the proposed observations? How broad or how deep?

 

GMVA/HSA Proposals

GMVA and HSA proposals use resources external to the NRAO/GBO. Additional negotiations are therefore necessary to finalize the scheduling priorities. The TAC therefore does not set the scheduling priority for GMVA and HSA proposals. We will take the normalized linear-rank and any TAC comments and lobby for the TAC in these negotiations to converge on a scheduling priority.

 

Final Comments

Proposals that support research for student theses will have been given any “score bumps” deemed appropriate by the cognizant SRP.

Some proposals have led the relevant SRP or the technical reviewer to note special questions, concerns, or recommendations they wish the TAC to consider. NRAO/GBO staff will examine these comments and raise them as appropriate during the TAC's deliberations.

Finally, it may be the case that a TAC member, in his/her capacity as SRP Chair, would like to bring a proposal(s) to the attention of the TAC during its f2f meeting. Please contact the TAC Chair and Dana Balser, so that all TAC members can familiarize themselves with the proposal in question prior to the f2f TAC meeting.

 

Appendix. PST TAC Support

1- Login through the NRAO portal at my.nrao.edu

You will enter the PST at the Dashboard, which allows you to perform a number of functions related to proposal preparation and review, access documentation, and modify your user profile.

For TAC members, seven tabs should be visible below the National Radio Astronomy Observatory banner:

  • Dashboard

  • Proposals

  • Reviews

  • Data Processing

  • Obs Prep

  • Helpdesk

  • Profile

2- Click on the Reviews tab.

3- You will see a new page that has the same banner and primary tabs across the top as well as a number of secondary tabs below the primary tabs. Click on the secondary tab labeled TAC Meeting.

4- The TAC Meeting page again reproduces the banner, primary, and secondary tabs. It also displays in tabular form all proposals submitted for consideration by the TAC this semester, an options bar to the left of the page, and a search box below the secondary tabs.

Some proposals may be shaded gray across all columns on the TAC Meeting page. This indicates that the proposals have been held after a previous TAC meeting for consideration at the current TAC meeting.  The options bar to the left of the page allows one to filter the proposal list by telescope, science category, and proposal type. There might be a few proposals that are declared as joint with another NRAO/GBO telescope and the TAC may wish to consider such joint proposals back-to-back; a Joint Proposal filter can be set to help identify such proposals.

The search box allows one to enter an alphanumeric character string – e.g., the last three digits of the proposal code – to locate a particular proposal quickly.

The list of proposals displays the following information:

  • Column 1 shows the PST proposal ID, an “abstract” icon, a printer icon, and a download icon. Underneath the proposal ID is a brief summary of key information: Proposal PI, proposal type, joint if applicable, hours requested, whether thesis research is being supported, science category, and whether multiple VLA configurations are requested.

  • Column 2 shows the proposal title

  • Column 3 shows the linear-rank score

  • Column 4 shows the proposal scheduling priority (not used)

  • Column 5 shows the time requested by the proposers

  • Column 6 shows the time allocation recommended by the TAC (not used)

  • Column 7 displays TAC comments for the PI (see below)

  • Column 8 displays TAC comments to the NRAO (see below)

  • Column 9 indicates the completion status of the proposal’s consideration

  • Column 10 displays a link labeled “TAC Input” that opens a new panel

Clicking on the “abstract” icon in column one opens a pop-up window containing the proposal abstract. Clicking on the printer icon for a given proposal ID in column 1 allows one to print the proposal. Clicking on the download icon in column 1 allows one to transfer the proposal to disk. There are only two other items on which one can click, both of which result in the same action: that is, clicking on the proposal ID in column 1 has the same result as clicking on “TAC Input” in column 10.

5- Doing so opens a panel under the relevant proposal containing two tabs: one labeled “TAC Comments” (left) and one labeled “Modified Sessions” (right). The default display is associated with “TAC Comments”:

  • Column 1 of this display lists the proposal authors.

  • Column 2 shows the technical review of the proposal. The top portion provides reviewer “Comments to PI” – that is, comments that will be forwarded to the proposers as part of their proposal disposition – while the bottom portion provides “Comments to TAC”.

  • Column 3 shows the consensus comments from the relevant Science Review Panel. The top portion again shows “Comments to PI” whereas the bottom portion shows SRP “Comments to TAC”.

  • Column 4 is used to enter “TAC Comments to PI” (top window) and “TAC Comments to NRAO” (bottom window). When entered, these comments will be visible in columns 7 and 8, respectively, of the TAC Meeting page described above.

  • Column 5 has a check box that is used to indicate that the TAC has completed consideration of, and all associated actions relevant to, this proposal.

  • Column 6 allows one to save entries into the comment boxes in column 4 or to cancel and clear any entries.

Clicking on the “Modified Sessions” tab on the “TAC Input” page brings up a new panel under the proposal in question containing a list of sessions and source groups associated with the proposal.

6- NRAO/GBO staff will be responsible for entering TAC comments or making any changes to Sessions. PST TAC support is therefore limited to displaying proposals, filtering and sorting them, viewing linear rank scores, SRP consensus comments, and technical reviews; and enabling the entry of TAC comments to the proposing team and to NRAO.

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