Drawing the basin boundaries

Question

In my case, I need to use the following data file

Let's plot the basins

m = ReadList["LGs.dat", Number, RecordLists -> True];
getColor[m_List, i_Integer] := 
  Module[{s = m[[i, 3]]}, 
  Which[s == 4, Darker[Green], s == 6, Blue, s == 8, Cyan, s == 10, 
  Orange, s == 12, Purple, s == 14, Red, True, Black]];
data = Table[{PointSize[0.005], getColor[m, i], 
Point[{m[[i, 1]], m[[i, 2]]}]}, {i, 1, Length[m]}];
S0 = Graphics[data];
P0 = Show[{S0}, Axes -> False, Frame -> True, 
  FrameLabel -> {"α", "δ"}, FrameStyle -> Thick, 
  RotateLabel -> False, 
  LabelStyle -> Directive[FontFamily -> "Helvetica", 22], 
  AspectRatio -> 1, PlotRange -> All, PlotRangeClipping -> True, 
  PlotRangePadding -> 0, ImageSize -> 500]

My question is: how can I draw a black solid line, thus highlighting the basin boundaries?

EDIT

Following @yarchik 's suggestion I get the following output

As you can see, the boundary lines are very ugly. Is there a way to obtain nice, smooth solid lines inicating the basin boundaries?

Answer 1

Out-of-box solution (left figure):

ListContourPlot[m[[All, 1 ;; 3]], 
 ContourStyle -> Directive[Black, Dashed], 
 ColorFunction -> "Rainbow",
 ImageSize -> Small, 
 FrameLabel -> {"α", "δ"}, 
 PlotTheme -> "Monochrome"]

This is pure esthetics consideration that the contours are dashed, the image is small, the theme is monochrome. It is fully customizable within ListContourPlot as shown below for different colors.

Explicitly specify the ColorFunction(right figure)

ListContourPlot[m[[All, 1 ;; 3]], 
 ContourStyle -> Directive[Black, Dashed], 
 ColorFunction -> (Which[# < 5, Darker[Green], # < 7, Blue, # < 9, 
     Cyan, # < 11, Orange, # < 13, Purple, # < 15, Red, True, 
     Black] &), 
 ColorFunctionScaling -> False, 
 ImageSize -> Small, 
 FrameLabel -> {"α", "δ"}, 
 PlotTheme -> "Monochrome"]