Plotted entries from OPSLOG files in VIMOS report ZEROPOINTS_U, plot 2, data set parQ1:

DATE       MJD-OBS      parameter values
==========================================================================
2008-11-21 54791.002905 26.6476955913461	parQ1
2008-11-21 54791.345932 26.3945713542855	parQ1
2008-11-21 54791.999520 26.6512184642709	parQ1