Title: Doing more with less: Leveraging existing and planned investments in radio astronomy infrastructure through commensal, lower-frequency observing.
Authors: N.E. Kassim (NRL), C.J. Law (UCB), P.S. Ray (NRL), S. Burke-Spolaor (NRAO), T.E. Clarke (NRL), P. Demorest (NRAO), G.C. Bower (ASIAA), E.J. Polisensky (NRL), J.S. Deneva (NRC-NRL), S. Giancintucci (CPI-NRL), W.M. Lane-Peters (NRL). B. Butler (NRAO), M. Rupen (DRAO)
The relentless drive towards transformational science is increasingly corralling scarce radio astronomy resources towards a limited number of instruments developed on a grand scale. At higher frequencies the expenses are naturally quite high, driven by cryogenics, expansive bandwidths, and stringent mechanical tolerances. While costs are often lower at longer wavelengths, tight budgets have nonetheless left the pursuit of large projects at lower frequencies lagging. Commensal observations can break this paradigm, by leveraging existing radio astronomy capital investments to pursue compelling lower frequency science for what can amount to pennies on the dollar. Past and current examples include Arecibo feeds scanning the sky in opposing directions, GMRT and WSRT dual frequency nested feed systems, V-FASTR on the VLBA, and the legacy VLA accommodating concurrent primary- and Cassegrain-focus observations.
We review two modern examples of commensal systems on the JVLA: the VLA Low Band Ionosphere and Transient Experiment (VLITE, ~330 MHz), and the realfast experiment (~1.4 GHz) to detect fast radio bursts (FRBs). We suggest these two lower frequency systems, doubly commensal when operated simultaneously as planned, can serve as additional models for how to do more with less. They can inspire foresight in the design of new facilities while also illustrating that out of the box approaches can revitalize existing facilities for leading-edge science with modest financial investment. Furthermore, with their naturally larger fields of view, we suggest such systems offer a means of achieving a balanced approach to exploring more of the radio spectrum and sky, in an efficient manner. Finally, the opportunity of measuring temporal correlation, spectral information, and extracting an accurate, interferometric-based position for FRBs across realfast and VLITE reminds us that no specific region of the radio electromagnetic spectrum, either high or low, has a monopoly on transformational science.
