This paper presents the third extension to the Very Large Baseline Array
(VLBA) Calibrator Survey, containing 360 new sources not previously
observed with very long baseline interferometry (VLBI). The survey, based on 
three 24 hour VLBA observing sessions, fills the areas on the sky above 
declination -45 degr where the calibrator density is less than 
one source within a 4 degr radius disk at any given direction. 
The positions were derived from astrometric analysis of the group delays 
determined at 2.3 and 8.4 GHz frequency bands using the Calc/Solve 
software package. The VCS3 catalogue of source positions, plots of 
correlated flux density versus the length of projected baseline, contour 
plots and fits files of naturally weighted CLEAN images as well as 
calibrated visibility function files are available on the Web at 
http://gemini.gsfc.nasa.gov/vcs3