The NRAO VLBA calibrator survey is very useful to search for a continuum source which can be used as a reference source to carry out the delay, bandpass, and phase calibrations.
The source list of this calibrator survey can be found at the following VLBA homepage,
For delay calibrations and bandpass calibrations, calibrators with 1 Jy or brighter are strongly recommended as listed in the VLBA fringe finder survey:
Interval of observing calibrator scans must be shorter than 1 hour to track the delay and delay rate in the correlation process.
The receiver noise temperature (blue crosses) and the system noise temperature (red open circles) at the zenith in the K band and the Q band at the Mizusawa station.
The zenith system noise temperature (red filled circles) at the K band (left) and the Q band (right) in the Ulsan station.