Plotted entries from OPSLOG files in NACO report DAILY_DARKRON, plot 2 (data set ronFNS3_HC):
(DATE changes at 21:00 UT or MJD-OBS = xxx.875)
DATE       	MJD-OBS      	values
====================================================
2013-05-21	56434.429370050000000	2.30202711004223
2013-05-24	56437.466728340000000	2.31555798420936