Radio observations using facilities of the Arecibo Observatory (AO) will be important to Fermi's scientific explorations. This Fermi-AO cooperative arrangement therefore commits observing time at AO for coordinated observations of Fermi sources, to be awarded on a competitive basis. The scientific programs supported within this arrangement will be those that are enhanced by the combination of Fermi observations and investigations using the radio facilities operated by AO. The philosophy of the approach, in keeping with the missions of both Fermi and AO, 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 AO and Fermi that will take place within the Fermi Guest Investigator (GI) Program. These two opportunities, the "Joint Proposal Opportunity" and the "Cooperative Proposal Opportunity," are described in turn below.
Arecibo Observatory is home to the 305-m William E. Gordon radio telescope, the largest single-dish telescope in the world, which is available to the global scientific community for astronomical observations at wavelengths between 6 m and 3 cm (frequencies of 47 MHz to 10 GHz). The 305-m dish provides more collecting area in this band than all other U.S. radio telescopes combined; its unique sensitivity enables investigations not possible elsewhere. AO telescope time is generally allocated competitively for PI proposals. AO is funded by the National Science Foundation as a research facility that operates in an “open skies” mode for the entire astronomical community.
The first element of the Fermi-AO cooperative program is a Joint Proposal Opportunity, whereby potential radio observers submit proposals for Fermi funding and future AO observations through the Fermi GI portal. AO will make telescope time available for the Fermi GI program. In turn, Fermi/NASA will make data-analysis funding available to successful U.S.-based investigators requesting AO observing time through the GI process. These proposals may include both AO and Fermi pointed observations, although pointed Fermi observations will be rare, and most successful proposals are expected to make use of Fermi survey data. The peer-reviewed GI proposal-evaluation process will identify programs with sufficient science justification to be allocated funding by Fermi, and those that fall within the constraints of AO observing time made available to the program will be allocated AO observing time without additional scientific review, provided they demonstrate technical feasibility.
Proposals for AO observing time submitted through the Fermi GI program are likely to be successful only if they make use of the unique capabilities of AO; proposal evaluation will include an assessment of the radio telescope requirements, including scheduling feasibility (see below), and investigations that are more appropriately carried out with other radio telescopes will be rejected. Only proposals equivalent to Regular AO proposals, those requesting fewer than 300 hours of observing time, will be eligible to be submitted for future observing time. AO Large Proposals (300 hours or more) will not be eligible because of their potential large impact on observing time, but will be eligible for funding via the Cooperative Proposal Opportunity (see below). Some examples of AO observations that would be acceptable might include, but are not limited to, the following:
The actual amount of AO observing time allocated via the Joint Fermi Opportunity will depend on the scientific quality of the proposals and on proposal pressure. The latter point is especially significant given the unique sky coverage and scheduling constraints of AO's 305-m dish, which result in substantially increased oversubscription during night-time at all Local Sidereal Times (LSTs) and especially when the Galactic Plane is visible. In practice, then, Joint Fermi proposals will have to meet a higher standard to be competitive for observations between 17h and 20h LST; conversely, high Galactic-latitude time may be somewhat easier to obtain. AO's technical (including scheduling) feasibility assessment for proposals that request highly-oversubscribed time will therefore include consideration of scientific merit as determined by the Fermi GI process. It is anticipated that a maximum of 300 hours per year of AO scientific observing time, distributed across the sky and across local day and night times, would be made available on the 305-m. If there are very strong scientific proposals for more time, and the Fermi mission has funds available to support data analysis, the Fermi Project Scientist will request additional time from the AO Director, who will set up an AO mechanism to evaluate and respond to this request.
Accepted regular AO proposals may include observations that have some overlap with observations approved in the Fermi GI Cycle. AO and the Fermi 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. A team that has duplicate proposals (or portions of proposals) accepted by AO and Fermi will receive only one allocation of observing time.
Proposals for AO observing time that are submitted directly to AO and that will enhance the Fermi mission's scientific return also may be eligible for NASA funding through the Fermi GI program. These proposals will be AO Large Proposals (requesting 300 or more hours of AO observing time) and Urgent Proposals, which respond to time-critical, transient events. AO receives and evaluates Large Proposals at each of its proposal deadlines, twice per year, whereas Urgent Proposals are considered at any time. These proposals are distinguished from those of the Joint Proposal Opportunity in that they would involve requests for Fermi GI funding that are made subsequent to AO approval of observing time. Proposers of AO observations who also intend to propose for Fermi funding via this route must indicate their intentions clearly in the AO proposal, and all information related to the AO review of successful proposals will be forwarded to the Fermi mission for their evaluation. Note that the award of AO observing time will not be a guarantee of Fermi funding; likewise the observing time is not contingent on Fermi funding in this case.
For results obtained using Fermi and AO facilities, proper attribution to Arecibo Observatory must be included in all publications, conference proceedings, posters, abstracts and talks and colloquia, as in the following: "The Arecibo Observatory is operated by SRI International under a cooperative agreement with the National Science Foundation (AST-1100968), and in alliance with Ana G. Méndez-Universidad Metropolitana, and the Universities Space Research Association." Fermi attribution will be the same as for all other use of Fermi data products.