Scientific applications of e-VLBI

Paper in proceeding, 2009

The advantages of e-VLBI over traditional media-recorded VLBI are briefly discussed. These advantages lie in two broad areas, those which reduce the operational burden of VLBI and those which enable wholly new kinds of observations to be made. In the first category, e-VLBI contributes to increases in reliability, to a more convenient way to use the instrument, reduced manpower effort and an easing of scheduling constraints. It also allows us to more easily expand bandwidth without building new recording equipment. In the second area the obvious advantage is in the increased speed of results from e-VLBI, which allows rapidly evolving sources to be observed and the next observations planned. A less appreciated, and yet to be fully realised e-VLBI advantage, especially when married to real time software correlation, is that of automation. Automated media-less operations will allow new types of long duration survey VLBI observations to be made lasting weeks to months. Potentially such a system could be used to create an always-on few telescope VLBI network which would follow up all suitable transient detections for accurate radio position and structure determination. An important and continuing benefit of the e-VLBI developments of recent years has been the closer integration and merging of connected element and long baseline interferometry via the e-MERLIN and e-LOFAR projects. The long term prospects for this synergy and the implications for long baseline centimetre wavelength interferometry in the era of the SKA are briefly mentioned.