SPATIAL SOURCE DISTRIBUTION OF BULGES FROM SURFACE PHOTOMETRY - APPLICATION TO NGC-2841

We tackle here the problem of obtaining the spatial density of sources rho in the bulge of a spiral galaxy using bidimensional surface photo metry. V,R,I,Z CCD images, taken with the 4.2m William Herschel Telesc ope at seeing limit resolution (0.5''-1.1''), yield the photometric pa rameters for the galaxy NGC 2841. The necessary procedure prior to obt aining a surface density distribution of luminosity sigma correspondin g to the bulge is explained and applied to this galaxy. A method is pr oposed to treat the integral relationship between the spatial distribu tion rho(R) and the observed surface distribution sigma(r). The analys is of the position angle and ellipticity variations with radius takes to the possible presence of a stellar bar structure within the inner t en arcseconds of the galaxy. In the case of NGC 2841, the misalignment between the position angle of the isophotes corresponding to the bulg e and the disc components, gives evidence to support the presence of a non-axisymmetric bulge for the galaxy. For this galaxy, it is necessa ry to reproduce the light distribution of the bulge geometry consistin g of a family of triaxial ellipsoids with variable axial ratios.