The zeropoint is calculated on the star of the month. It is calculated using <br>
zpoint=mag + 2.5*log10(flux/DIT) <br>
where mag is the magnitude of the object in N band, flux is the Target Photometry of beam A or B (measured in bin2),
and DIT is the detector DIT. There are no corrections applied.</font><p><font size="2">

Please note that the zeropoint parameters in the QC1 database are misleadingly called
averaged_err_photA and averaged_err_photB.