The Gamma-ray Large Area Space Telescope

The NRAO Cooperative Agreement

Radio observations using the NRAO facilities will be important to the scientific exploration by GLAST. Therefore, this GLAST-NRAO cooperative arrangement commits observing time on NRAO telescopes for coordinated observations of GLAST sources, to be awarded on a competitive basis. The scientific programs that will be supported within this program are those that are enhanced by the combination of GLAST observations with investigations using the radio facilities operated by NRAO. The philosophy of the approach, in keeping with the missions of both GLAST and NRAO, will be that of maximum data availability and maximum scientific return for the entire user community.

This cooperative arrangement includes two distinct types of collaborative observations and funding opportunities between NRAO and GLAST that will take place within the GI program. To distinguish these two opportunities, we call them the "Joint Proposal Opportunity" and the "Cooperative Proposal Opportunity," respectively. The two opportunities are described in turn below.

Background Description of NRAO Radio Telescopes

The NRAO operates the Very Long Baseline Array (VLBA), a milliarcsecond-resolution continent-wide interferometer array; the Very Large Array (VLA), to be "replaced" by the Expanded VLA (EVLA) in 2010, an arcsecond-resolution centimeter-wave interferometer array; and the Robert C. Byrd Green Bank Telescope (GBT), a precise 100m single-aperture telescope. In addition, the NRAO is the North American Executive of the Atacama Large Millimeter/Submillimeter Array (ALMA), to be completed in 2012, with first science using about 15 telescopes in 2010. The present agreement covers the GBT, VLA, and VLBA, with the potential of adding ALMA and EVLA as they come on line. The total amount of scientific observing time used on the operational NRAO telescopes ranges from 4500 to 6500 hours per year. The GBT, VLA, and VLBA are pointed telescopes generally allocated for PI proposals; their data proprietary period is 12 months, beginning at the time of the last observation associated with a proposal. NRAO also accepts "Large Proposals" requesting at least 200 hours of NRAO observing time at intervals of 8-12 months. NRAO is funded by NSF as a research facility that operates state-of-the-art telescopes in an "open skies" mode for the entire astronomical community.

Joint Proposal Opportunity

The first GLAST/NRAO opportunity is a Joint Proposal Opportunity, whereby potential radio observers submit proposals for GLAST funding and future NRAO observations through the GLAST GI portal. A range of telescope time will be made available by NRAO for the GLAST GI program. In turn, GLAST/NASA will make data-analysis funding available to successful U.S.-based investigators requesting NRAO observing time through the GI process. In GLAST Cycle 1, these proposals will make use of GLAST survey data products, while those for succeeding cycles may also include both NRAO and GLAST pointed observations. The peer-reviewed GI proposal-evaluation process will identify programs with sufficient science justification to be allocated funding by GLAST, and those that fall within the agreed-on range of NRAO observing time will be allocated NRAO observing time without additional scientific review.

Proposals for NRAO observing time submitted through the GLAST GI program are likely to be successful only if they make use of the unique capabilities of the NRAO telescopes; proposal evaluation will include an assessment of the radio telescope requirements, and those that are more appropriately done with other radio telescopes will be rejected. Only proposals equivalent to "regular" NRAO proposals, those requesting fewer than 200 hours of observing time, will be eligible to be submitted for future observing time. NRAO Large Proposals (200 hours or more) will not be eligible because of their potential large impact on the available funding and observing time, but will be eligible for funding via the Cooperative Proposal Opportunity (see below). Some examples of NRAO observations that would be acceptable might include, but are not limited to, the following:

  • High-resolution rapid source surveys for spectral-energy distributions and candidate identification
  • High-resolution imaging to follow morphological evolution of flaring sources
  • Timing of weak millisecond pulsars to enable folding of the gamma-ray light curves with respect to the pulsar period
  • Multi-frequency spectral monitoring of radio-weak, flaring gamma-raysources

The radio data will be the property of the proposers for the standard NRAO 12-month proprietary period.

The actual amount of NRAO observing time allocated via the Joint GLAST Process will depend on the amount of proposal pressure and the scientific quality of the proposals. We anticipate that a maximum of 10% of the NRAO scientific observing time would be made available on GBT, VLA, and VLBA, or up to 450-650 hours per year on each telescope. If there are very strong scientific proposals for more time, and the GLAST mission has funds available to support data analysis, the GLAST Project Scientist will request additional time from the NRAO Director, who will set up an NRAO mechanism to evaluate and respond to this request.

Accepted regular NRAO proposals may include observations that have some overlap with observations approved in the GLAST GI Cycle. NRAO and the GLAST mission will resolve such duplications on a case-by-case basis; the default resolution will be that a single observation will be made and the data shared among the respective teams.

Cooperative Proposal Opportunity

Direct proposals for NRAO observing time that will enhance the scientific return associated with the GLAST mission also may be eligible for NASA funding through the GI program. These proposals will be of two NRAO types-Large Proposals (requesting 200 or more hours of NRAO observing time) and Target of Opportunity proposals, which respond to time-critical transient events. NRAO typically accepts and evaluates Large Proposals annually, whereas Target of Opportunity proposals are accepted at any time. These proposals are distinguished from those of the Joint Proposal Opportunity because they would involve requests for GLAST GI funding that are made subsequent to NRAO approval of observing time. Proposers of NRAO observations who also intend to propose for GLAST funding via this route must indicate their intentions clearly in the NRAO proposal, and all information related to the NRAO review of successful proposals will be forwarded to the GLAST mission for their evaluation. Note that the award of NRAO observing time will not be a guarantee of GLAST funding; likewise the observing time is not contingent on GLAST funding in this case.

See http://www.nrao.edu/administration/directors_office/largeprop.shtml and http://www.vla.nrao.edu/astro/proposals/rapid for further descriptions of the NRAO Large and Target of Opportunity proposals.

Credits and Attributions

For results obtained using GLAST and NRAO facilities, proper attribution to NRAO facilities must be included in all publications, conference proceedings, posters, abstracts and talks and colloquia, as in the following: "The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc." GLAST attribution will be the same as for all other use of GLAST data products.