The VLBA RSRO Program
The VLBA Resident Shared Risk Observing (RSRO) program provides users with early access to new capabilities in exchange for a period of residency in Socorro to help commission those capabilities. Users are invited to propose areas in which they would be willing to contribute two months or more (subject to negotiation) of concentrated development activity while resident at the Domenici Science Operations Center in Socorro. Several such developments, either currently underway or proposed, are listed below, but proposals for any area of user interest are welcome. Details of participation in the VLBA RSRO program are provided in a following section.
Suggested RSRO Studies
"Y1" VLBI observing on the VLA. The "Y27" phased-VLA capability is currently limited to a single subarray. Thus, any VLBI observation either uses, or idles, each of the VLA's 27 antennas, which can only be justified when a large number are required for scientific success. RSRO participants could contribute to extending the VLBI mode to a subarrayed configuration, to re-establish the "Y1" mode, with a single VLA antenna joining the VLBA. That capability was valued in the pre-EVLA era for studies of intermediate-scale sources requiring baselines between the VLA's A configuration and the VLBA's shortest spacings.
Wideband VLBI in HSA and global arrays. New instrumentation supporting VLBI observations at recorded data rates of 2 Gbps and greater has been developed at a number of institutions worldwide. While the general specifications of these systems are quite similar in a broad sense, and some convincing "zero baseline" fringe tests have been carried out in laboratory settings, detailed compatibility of both operation and control has yet to be established. RSRO participants could benefit from enabling and carrying out the first routine global-scale high-sensitivity VLBI observations. Specific RSRO areas expected to enhance the HSA's current capabilities are highlighted in the Call for Proposals for observing semester 2014A: PFB and DDC-8 capabilities on the Y27 phased VLA, and full implementation of the DDC-4 system at Effelsberg.
Rapid response capability. Dynamically scheduling the VLBA in response to a trigger should allow observing to begin within 5 to 10 minutes, in opportune situations. This RSRO program would entail setting up software infrastructure and operations procedures for automated preemption of ongoing array activity, subject to prioritization constraints.
Participation in the VLBA RSRO Program
The primary requirement of the RSRO program is that there be at least one expert from each participating group in residence in Socorro. These experts must be able to contribute effectively to commissioning while incurring as little overhead from VLBA staff as possible. It is expected that NRAO will be able to provide accommodation in the NRAO Guest House for participants in the RSRO program, subject to availability.
Interested VLBA users should submit an RSRO proposal using the NRAO Proposal Submission Tool in response to the Call for Proposals for observing semester 2014A (deadline August 1, 2013). The proposal should include a scientific justification, as for normal proposals, which will be peer reviewed as part of NRAO's time allocation process. Selecting "VLBA RSRO" from the "Observing Mode" menu on the Resources page makes an "RSRO Comments" text-entry facility available for describing the technical resources required. A description of the personnel who will be involved in the residency along with their expertise and proposed dates of residency should also be included in the new technical justification section.
Acceptance of RSRO proposals will be based on both the outcome of the time allocation process and a review by NRAO staff to assess how the proposed capability and associated commissioning activities fit with VLBA priorities.
One week of resident commissioning effort will be required for every 20 hours of VLBA time awarded to an RSRO project. Residency must be at least 2 months, which is considered the minimum time useful to become familiar with technical aspects of the VLBA and begin to contribute effectively. In exceptional circumstances, NRAO is prepared to consider proposals for dividing this into shorter visits, subject to negotiation. The period(s) of residency should in general occur in advance of the observing time awarded in order to commission the requested capabilities.
It should be noted that having a member of the NRAO staff as a collaborator on an RSRO proposal will not satisfy the residency requirement. Furthermore, graduate students will in general not satisfy the residency requirement, although there may be exceptional cases. Graduate students will be allowed to accompany their advisors as long as the advisor takes primary responsibility for managing the student's efforts. Resident personnel will work under NRAO management in order to optimize the overall commissioning effort. A set of deliverables will be agreed upon in advance of the start of the residency.
The types of proposals considered under the RSRO program may include large (>200 hours) as well as normal projects. Qualified large projects proposed by consortia will be considered as long as the residency requirements are met. A single individual may satisfy the residency requirement for several small projects.
We emphasize the "shared risk" nature of the RSRO program. Since observers will be attempting to use capabilities under development and in the process of being commissioned, NRAO can make no guarantee of the success of any observations made under this program, and no additional commitment is made beyond granting the hours actually assigned by the peer review process.