  A 20-hour VLBI observation with the NRAO VLBA and GBT in the NOAO Bootes
field reaches an rms noise of 9 microJy per beam at 1.4 GHz. Three sources were
detected at 10-milliarcsecond resolution within the GBT primary beam of FWHM
8.6', including the 20-milliJy calibrator and two sub-milliJy sources. By
tapering the visibility data, portions of the VLBA primary beam of FWHM 29'
were imaged at poorer sensitivity and resolution to yield five further
detections. New developments at JIVE will permit deeper and wider VLBI surveys
at full sensitivity and resolution, enabling new types of survey science.
