Plotted entries from OPSLOG files in ISAAC report DARK_SW_DC, plot 2 (data set p_R_UL):
(DATE changes at 21:00 UT or MJD-OBS = xxx.875)
DATE       	MJD-OBS      	values
====================================================
2013-05-20	56433.037855310000000	2.54514442054742
2013-05-20	56433.531537800000000	2.50827810111267