set term postscript 
set output "mer98-04.ps"
set angles degrees
set polar
set offsets 0.5 0.5 0 0
set title \
 "Mercury geocentric longitude and distance each 2 days"
plot "mer1998" using 2:4 with lines, \
     "mer1998" using 2:4 with points, \
     "mer1999" using 2:4 with points, \
     "mer2000" using 2:4 with points, \
     "mer2001" using 2:4 with points, \
     "mer2002" using 2:4 with points, \
     "mer2003" using 2:4 with points, \
     "mer2004" using 2:4 with lines