The VLBA Calibrator Search for the BeSSeL Survey
  We present the results of a survey of radio continuum sources near the Galactic plane using the Very Long Baseline Array (VLBA). Our observations are designed to identify compact extragalactic sources of milliarcsecond size that can be used for parallax measurements in the Bar and Spiral Structure Legacy Survey. We selected point sources from the NVSS and CORNISH catalogs with flux densities above 30 mJy and within $1.5\degr$ of known maser targets. Of the 1529 sources observed, 199 were detected. For sources detected on 3 or more baselines, we determined accurate positions and evaluated their quality as potential calibrators. Most of the 1330 sources that were not detected with the VLBA are probably of extragalactic origin. 
K. Immer, A. Brunthaler, M. J. Reid, A. Bartkiewicz, Y. K. Choi, K. M.   Menten, L. Moscadelli, A. Sanna, Y. W. Wu, Y. Xu, B...
astro-ph.GA