Plotted entries from OPSLOG files in VIMOS report BIASLEV, plot 3 (data set parQ2hi):
(DATE changes at 21:00 UT or MJD-OBS = xxx.875)
DATE       	MJD-OBS      	values
====================================================
2012-02-07	55965.489872	200
2012-02-08	55966.386408	198
2012-02-09	55967.458397	198