Plotted entries from OPSLOG files in ISAAC report DARK_SW_DC, plot 5 (data set p_R_LL):
(DATE changes at 21:00 UT or MJD-OBS = xxx.875)
DATE       	MJD-OBS      	values
====================================================
2013-05-20	56433.037855310000000	2.26455792031434
2013-05-20	56433.531537800000000	2.23498089964764