Estimate UVW from image parameters

                # the phase center PSF
                self.phasePSF = phasePSF;
                # Observed frequency
                self.freq0 = freq0 or 1.;
                # the compression in time
                self.dtime = dtime or 1;
                # the compression in frequency
                self.dfreq = dfreq or 1;
                # the resolution or the pixel size in radian
                self.resolution = np.pi*(cellsize/3600.)/180.;
                self.npix, n = phasePSF.shape
                Fov = n*self.resolution
                Delta_u, Delta_v = (1./Fov, 1./Fov)
                u = np.linspace(-(n-1)/2*Delta_u,(n-1)/2*Delta_u,n)
                v = np.linspace(-(n-1)/2*Delta_v,(n-1)/2*Delta_v,n)
                uu,vv = np.meshgrid(u,v)
                # angle of orientation
                vv[vv==0]=1.e-9
                angle = np.arctan(uu/vv)
                #angle[uu==0]=1e-9
                # uv distance in radian
                self.uvd = np.sqrt(uu**2 + vv**2)
                # angular velocity on one year
                ang_velocity = 2.*np.pi/(3600.*24.)
                self.du =ang_velocity*self.uvd*(-1*np.sin(angle))
                self.dv =ang_velocity*self.uvd*np.cos(angle)
                self.UVdomain = np.fft.fftshift(np.fft.fft2(self.phasePSF))
                print ("**************************** here ************************************************")
                self.liste=[]
                self.cellsize = cellsize
                self.npixDirty = npix