Plotted entries from OPSLOG files in XSHOOTER report NLINE_VIS, plot 3 (data set por):
(DATE changes at 21:00 UT or MJD-OBS = xxx.875)
DATE       	MJD-OBS      	values
====================================================
2012-05-17	56065.467181	15
2012-05-18	56066.718352	15
2012-05-20	56068.641827	15
2012-05-22	56070.720108	15