The WATTS' charts provide the elevation of the limb of the moon using 1800 contour maps (step of 0.2deg) that cover all libration ranges of the moon. The contours of the maps were digitised by H.M. Nautical Almanac Office in the late 1960's, and then converted to a grid format by US Naval Observatory in the early 1970's. These charts are present in 2 forms: as an ascii file watts.dat (without carriage-return or line-feed!), or as a 3-D FITS file watts.fit (transformed from the ascii files with the program "make_fit.c"). More details, especially about the transformations between the original charts and the files stored here, and the special processing of the 36.0{deg} map (map#181), can be found in the "doc.txt" file.