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The VLBA RSRO Program

by Jonathan Romney last modified Jun 06, 2019 by Mark Claussen


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.  Proposals for any area of user interest are welcome; several desirable developments are listed below.  Details of participation in the VLBA RSRO program are provided in a following section.

Some Suggested RSRO Studies

Many pulse cal tones per channel.  The DiFX software correlator has the capability to extract every pulse cal tone in each channel (up to 128 in the most extreme case), compared to just two channels, which is the historical norm.  AIPS now has recent support for this in the form if increased capability of existing tasks and several new ones.  Many pulse cal tones may offer several new calibration or data assessment techniques.  Users seeking early use of this capability are invited to propose for a RSRO project with goals of validating the new software and developing/documenting best practices for its use.

Improved troposphere model. The Vienna Mapping Function formulation used to characterize the tropospheric delay has been implemented for the DiFX correlator.  Use of this updated model is thought to improve phase referencing at high frequencies and the precision of relative astrometry. A RSRO applicant should expect to spend a few weeks in Socorro working with staff to evaluate the effectiveness of the new model, leading to it being commissioned as a feature available to all observers.

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.  Establishing a general rapid-response capability that would cover all conceivable cases is not considered feasible, so this RSRO program would allow the definition of triggers and responses suitable to a specific case of interest to the proposing user group.  The work required would include setting up software infrastructure and operations procedures for automated preemption of ongoing array activity, subject to prioritization constraints.

3mm VLBI with the LMT. New VLBI equipment has been installed at the Large Millimeter Telescope in Mexico, provided through a collaboration with MIT Haystack Observatory and the Smithsonian Astrophysical Observatory, enabling VLBI using their Redshift Search Receiver at 3mm.  Further commissioning will be needed to make this capability fully operational with the rest of the High Sensitivity Array.  RSRO participants are invited to assist with this effort.


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 will to reside in Socorro and to contribute to commissioning, while incurring as little overhead from VLBA staff as possible. Limited support for accommodation in the NRAO Guest House for participants in the RSRO program may be available.

RSRO proposals should be submitted using the NRAO Proposal Submission Tool in response to a regular proposal call.  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 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.

    In general, one week of resident commissioning effort is expected for every 20 hours of VLBA time awarded to an RSRO project, subject to negotiation. Ideally, residency should be at least 2 months, which is the minimum time useful to become familiar with technical aspects of the VLBA and to contribute effectively to commissioning. The period(s) of residency should in general occur in advance of the observing time awarded in order to commission the requested capabilities.

    It is possible for a member of the NRAO scientific staff to satisfy the residency requirement on an RSRO proposal.  NRAO staff considering providing the residency requirement for an RSRO proposal should consult with their supervisor for further information.  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.