  Context. The current algorithms used for the calibration and analysis of very
long baseline interferometry (VLBI) networks that only use linear polarizers
(as is the case of the VLBI Global Observing System, VGOS) do not properly
account for instrumental and source-intrinsic polarimetry, which can cause
errors in geodetic and astronomical products. Aims. We aim to develop a
calibration pipeline for VLBI interferometers that observe in a basis of linear
polarization, as is the case of VGOS. The products from this pipeline can be
used to obtain valuable full-polarization astronomical information from the
observed sources, and they can be used to potentially improve the geodetic
results. Methods. We used the algorithm PolConvert to write the correlation
products in a basis of circular polarization that is compatible with the
standard VLBI calibration procedures. In addition to this, we implemented a
wide-band global fringe-fitting algorithm that accounts for dispersive effects
(ionospheric delay) and allows us to perform full-polarization imaging of all
the observed sources, covering the whole frequency band of VGOS. Results. We
present the outcome of our pipeline applied to a global IVS VGOS epoch of
observations and show example imaging results in total intensity and
polarization. We also discuss issues encountered during the analysis and
suggest points of improvement in the VGOS system for an optimum geodetic and
astronomical exploitation of this interferometer.
