Interferometer phase calibration sources - I. The region Formula

We present a catalogue of 800 compact radio sources in the declination range $$35^{\circ} \leq \delta \leq 75^{\circ} $$ whose positions have been measured to an rms accuracy of ~ 12 milliarcsec with the VLA. They are primarily intended for use as phase reference sources for the Jodrell Bank MERLIN but they will also be suitable phase calibrators for the VLA and the VLBI networks.