Plotted entries from OPSLOG files in AMBER report P2VM_MK, plot 2 (data set P2VM_VIS23_MK2_ops):
(DATE changes at 21:00 UT or MJD-OBS = xxx.875)
DATE       	MJD-OBS      	values
====================================================
2013-05-03	56416.331853207600000	0.891851293090514