MgII Data:

The file mgcompV7.dat is a composite of data from several sources

Column 1:  Date in m/d/yr format
Column 2:  Day number in Julian Day (starting at the beginning of the Julian Calander about 4500 BC)
Column 3:  Mg Core to wing ratio scaled to the NOAA9/Nimbus7 data with blanks for missing data
Column 4:  A number from 0 to 4 indicating the source of each data point where
      Blank or 0 = No data
      1 = Nimbus7/NOAA9 Data (previously released)
      2 = NOAA 11 Data
      4 = UARS Solstice Data
      3 = NOAA 9 Data with new analysis technique (an attempt to work around bad data)

Besides this readme file and the mgcompV7.dat files, there are two files containing a paper on the 
creation of this data set.  This paper has been accepted for publication in JGR Space Physics.  The 
Mgii.doc is a MsWord file with high resolution figures and Mgii.rtf is a Rich Text  Format with lower 
resolution figures.  There is also MgII.txt file without figures.