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
====================================================
2012-02-06	55964.337644	2.37759152872333
2012-02-07	55965.369912	2.37114323320409
2012-02-08	55966.384569	2.32138897521809
2012-02-09	55967.363475	2.35229931212254