Plotted entries from OPSLOG files in VIMOS report IFUSTAB_HRo, plot 4 (data set parQ4):
(DATE changes at 21:00 UT or MJD-OBS = xxx.875)
DATE       	MJD-OBS      	values
====================================================
2012-05-20	56068.524917	199
2012-05-21	56069.012299	198
2012-05-21	56069.050919	199
2012-05-21	56069.089372	198
2012-05-21	56069.127306	200
2012-05-21	56069.164283	198
2012-05-21	56069.201145	200
2012-05-21	56069.240030	199
2012-05-21	56069.263651	199
2012-05-21	56069.287891	199
2012-05-21	56069.491706	199
2012-05-22	56070.515295	199
2012-05-23	56071.040466	199
2012-05-23	56071.174951	199
2012-05-23	56071.194995	199
2012-05-23	56071.208484	199
2012-05-23	56071.525917	199