Plotted entries from OPSLOG files in FORS2 report BIAS_med_master, plot 6 (data set parC2m):
(DATE changes at 21:00 UT or MJD-OBS = xxx.875)
DATE       	MJD-OBS      	values
====================================================
2013-06-11	56455.460661220000000	13.2
2013-06-13	56457.395927990000000	11.8
2013-06-13	56457.397280690000000	11.8
2013-06-13	56457.398620190000000	11.8
2013-06-13	56457.400592750000000	11.8
2013-06-13	56457.438323910000000	11.8
2013-06-14	56458.595040180000000	7.1
2013-06-14	56458.597007640000000	7.1
2013-06-15	56459.440120410000000	10.4
2013-06-15	56459.457811250000000	10.5
2013-06-16	56460.445944310000000	11.4
2013-06-16	56460.447290760000000	11.4
2013-06-16	56460.448629100000000	11.4
2013-06-16	56460.450597610000000	11.4
2013-06-16	56460.511032030000000	11.3
2013-06-17	56461.269213430000000	8.8
2013-06-17	56461.334491370000000	8.9
2013-06-17	56461.397421750000000	9.0