  We present a calibration component for the Murchison Widefield Array All-Sky
Virtual Observatory (MWA ASVO) utilising a newly developed PostgreSQL database
of calibration solutions. Since its inauguration in 2013, the MWA has recorded
over thirty-four petabytes of data archived at the Pawsey Supercomputing
Centre. According to the MWA Data Access policy, data become publicly available
eighteen months after collection. Therefore, most of the archival data are now
available to the public. Access to public data was provided in 2017 via the MWA
ASVO interface, which allowed researchers worldwide to download MWA
uncalibrated data in standard radio astronomy data formats (CASA measurement
sets or UV FITS files). The addition of the MWA ASVO calibration feature opens
a new, powerful avenue for researchers without a detailed knowledge of the MWA
telescope and data processing to download calibrated visibility data and create
images using standard radio-astronomy software packages. In order to populate
the database with calibration solutions from the last six years we developed
fully automated pipelines. A near-real-time pipeline has been used to process
new calibration observations as soon as they are collected and upload
calibration solutions to the database, which enables monitoring of the
interferometric performance of the telescope. Based on this database we present
an analysis of the stability of the MWA calibration solutions over long time
intervals.
