When you wish upon a star: Future developments in astronomical VLBI

Abstract

In this paper, I present the likely technological development of VLBI, and its impact on the astronomical community over the next 1-5 years. VLBI is currently poised to take advantage of the rapid development in commercial off-the-shelf (COTS) PC-based products. The imminent deployment of disk-based recording systems will enable Gbps data rates to be achieved routinely by both cm and mm-VLBI networks. This, together with anticipated improvements in collecting area, receiver systems and coherence time is set to transform the performance of VLBI in terms of both baseline and image noise sensitivity. At the same time the feasibility of using fibre based communication networks as the basis for production, real-time VLBI networks will begin. Fantastic new correlator output data rates, and the ability to deal with these via powerful PC clusters promises to expand the typical VLBI field-of-view to scales previously reserved for connected, short baseline interferometers. By simultaneously sampling the summed response of all compact radio sources within (and indeed beyond) the half-power point of the VLBI telescope primary beam, simple self-calibration of the target field will ALWAYS be possible at frequencies below a few GHz. Unbiased, broad-band continuum surveys will be conducted over huge areas of sky, and (redshifted) spectral-features will be detected too. By the end of the decade the microJy radio sky will be accessible to VLBI: dozens of sources will be simultaneosuly observed, correlated, detected and fully analysed all within the same day.