Dear Neil, Thank you for the kind assistance. I downloaded this precipitation images from Famine Early Warning Systems Network of US Government http://earlywarning.usgs.gov/fews/africa/web/dwndailyrfe.php . When I open the file in ArcGIS and see spatial reference in properties, I so no reference. Is there any way out? Prabin, errr... If the original bil images are not georeferenced then no amount of assigning a coordinate system / projecting and what not is going to help. They are simply not georeferenced. You will have to go through a georeferencing step which involves picking control points from the image and assigning to these points their correct coordinates. But that is rather odd, where did this raster data come from? Neil
... View more