I just encountered a bug wherein when I generated a gamma nought tiff file from SLC product, the lat long of particular pixel in SLC file (as shown by SNAP ) are different than the lat long of that particular pixel in a gamma nought tiff file. I think there is an issue of georeferencing in the generation of gamma nought file. I am using Sentinel-1 SLC IW product. Kindly help.
How did you generate Gamma Nought? I wonder how you can read the lat/lon value of a tif file without geocoding it.
I just generated gamma nought directly, by selecting the calibrate option. As I was getting the lat long values for every pixel when I just opened the SLC image, so I thought that it is already georeferenced. I f I am wrong, kindly guide.
internal geocoding is not very precise. I would suggest applying the Range Doppler Terrain Correction to your image to have it projected to a map projection and also corrected for topographic distortions.
Ok. Thats why georeferencing is erroneous , so what should be the sequence i.e. I should first apply Range doppler terrain correction and then I should generate the gamma nought from that file?
first calibrate, then geocode 
Thanks a lot.