Plotted entries from OPSLOG files in ISAAC report DARK_LW_UCHB, plot 4 (data set p_STD_11):
(DATE changes at 21:00 UT or MJD-OBS = xxx.875)
DATE       	MJD-OBS      	values
====================================================
2012-05-19	56067.448230	2.61378223689988
2012-05-20	56068.452993	3.72713880527867
2012-05-20	56068.461877	1.22409612272336
2012-05-21	56069.450917	2.78245467267014
2012-05-22	56070.470249	2.6055279695948