RGB color values (0 to 255) for use by IDL routine CIE1931.pro in drawing a CIE chromaticity diagram
    R    G    B  indx wavelength (RGB values were determined by eye; they can be improved)
  200    0  225    1  400  violet-purple
  190    0  220    2  410
  180    0  210    3  420
  170    0  220    4  430
  170    0  230    5  440
  145    0  230    6  450
  125    0  240    7  460
   50    0  255    8  470
    0   50  255    9  480  blue
    0  255  255   10  490  cyan
    0  255  127   11  500
    0  255    0   12  510  green
   38  255    0   13  520
   77  255    0   14  530
  115  255    0   15  540
  154  255    0   16  550
  193  255    0   17  560
  231  255    0   18  570
  255  255    0   19  580  yellow
  255  150    0   20  590  orange
  255   83    0   21  600
  255   66    0   22  610
  255   50    0   23  620
  255   33    0   24  630
  255   15    0   25  640
  255    0    0   26  650  red
  255    0    0   27  660
  255    0    0   28  670
  255    0    0   29  680
  255    0    0   30  690
  255    0    0   31  700