Fast estimation of position and depth to magnetic sources can be done using Euler's homogeneity relation. This method is based on the use of vertical and horizontal gradients and does not need any assumption on the magnetization. The analytic signal can also be used to locate magnetic sources without making any assumption on the magnetization. Synthetic data examples are presented in this paper. These examples have been computed in order to investigate the sensitivity of the two methods and particularly the Euler deconvolution method where the choice of parameters such as the grid spacing, the structural index, the deconvolution window size and the tolerance, is very important to well determine the source location. Data from the Iracoubo region, in North West French Guyana has been interpreted to illustrate the techniques. This area is characterized by granitic massifs and Jurassic dykes.