Plotted entries from OPSLOG files in FORS2 report BIAS_med_master, plot 3 (data set parC2r):
(DATE changes at 21:00 UT or MJD-OBS = xxx.875)
DATE       	MJD-OBS      	values
====================================================
2012-02-03	55961.410037	14.4
2012-02-04	55962.408172	15.0
2012-02-04	55962.409512	15.0
2012-02-04	55962.411493	15.0
2012-02-04	55962.418671	15.0
2012-02-04	55962.441482	15.0
2012-02-04	55962.528718	15.3
2012-02-07	55965.350226	14.1
2012-02-07	55965.352195	14.1
2012-02-07	55965.359364	14.1