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
====================================================
2013-05-17	56430.370784730000000	204
2013-05-18	56431.271973270000000	201