Plotted entries from OPSLOG files in NACO report SLIT, plot 4 (data set angle_HC):
(DATE changes at 21:00 UT or MJD-OBS = xxx.875)
DATE       	MJD-OBS      	values
====================================================
2012-01-22	55949.408002	179.567434811208
2012-01-22	55949.408396	179.577393012933