I have shapefile (points) which I got from adding xy data in ArcMap from Excel table. I had Latitude/Longitude data. It is area of northern Australia.
For example (5 points):
Longitude 136.882 142.356 143.049 142.984 145.086
Latitude -12.249 -11.151 -12.659 -12.881 -15.135
What coordinate system should I define here and how?