Plotted entries from OPSLOG files in NACO report DAILY_DARKRON, plot 4 (data set darkDCR_HC):
(DATE changes at 21:00 UT or MJD-OBS = xxx.875)
DATE       	MJD-OBS      	values
====================================================
2013-05-18	56431.355868420000000	2.74333310127258
2013-05-19	56432.558785010000000	2.77333331108093