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
====================================================
2010-03-14 55270.532432 15.0
2010-03-14 55270.549219 15.0
2010-03-15 55271.418717 14.5
2010-03-15 55271.420057 14.6
2010-03-15 55271.422026 14.6
2010-03-15 55271.429145 14.6
2010-03-15 55271.486657 14.8
2010-03-15 55271.512552 15.0
2010-03-16 55272.434508 14.8
2010-03-16 55272.451861 14.9
2010-03-17 55273.419254 15.1
2010-03-17 55273.426694 15.1
2010-03-19 55275.422790 16.2
2010-03-19 55275.424135 16.1
2010-03-19 55275.426085 16.2
2010-03-19 55275.441459 16.1
2010-03-20 55276.451461 16.1