Plotted entries from OPSLOG files in VIMOS report MASK_ZERO, plot 8 (data set parY0Q4):
(DATE changes at 21:00 UT or MJD-OBS = xxx.875)
DATE       	MJD-OBS      	values
====================================================
2012-05-20	56068.854163	1362.84320643409
2012-05-21	56069.835750	1362.95251398828
2012-05-23	56070.875061	1362.86972942134
2012-05-23	56070.968835	1362.71935155585
2012-05-23	56070.977134	1362.79685152983