The Deepest and Widest VLBI Survey yet: VLBA+GBT 1.4 GHz observations in Bootes

Abstract

We present preliminary results from the deepest VLBI observations yet conducted. VLBA+GBT 1.4 GHz observations of a region within NOAO-N, reach an r.m.s. noise level of 9 microJy per beam. Three sources are clearly detected (> 7 sigma) within the inner 2 arcmins of the GBT primary beam, including two sub-mJy sources and the ``in-beam'' calibrator. In addition, by tapering the data, we map out a much larger area of sky, reaching well beyond the half-power point of the GBT primary beam. An additional 6 sources are detected in the extended field. We comment briefly on the scientific motivation for even deeper and wider VLBI surveys, and note that the summed response of sources in the field will permit self-calibration techniques to be employed in any region of the radio sky, including so-called ``blank'' fields.