The MegaCam zeropoints are calculated for each run using elixir and the Q97 calibration fields. We provide a CSV, updated shortly after the run is complete and the data is distributed, which you can download here.
This is an interactive plot: you can pan and zoom around to view the data range you are interested in, and you can mouse over each point to get useful information (the camera run id, the queue run id, the filter name, and the zero point).
By default, only u band zeropoints are plotted, because u band is the most sensitive to slight changes in the mirror condition. Click any of the filters in the legend to toggle them on/off.