Reference flux scale for MeerKAT: Long term observation and field modelling of PKS B0407-65

PKS B0407-65 is one of, primarily, three radio sources that are used to calibrate flux density measurements of the MeerKAT radio interferometer. In this memo we present a long term study of the stability of this standard calibrator. We derive a new spatio-spectral model of the calibrator and its surroundings, as well as its polarization properties. Truncated field models derived here are in use in the MeerKAT Science Data Processor (SDP) since 2020. Accompanying full-field models are made available for general offline calibration use.