1999PASP..111.1223N

We have obtained high-resolution R-band images of three BL Lacertae objects, Mrk 421, Mrk 501, and 1ES 2344+514, that have been detected at high-energy (TeV) γ-rays. Because of their TeV emission, these three objects have been targets of intensive optical monitoring during the last few years. We have studied the morphology of host galaxies by fitting ellipses and two-dimensional galaxy+core models to the observed surface brightness distribution. We find the host galaxies to be large (effective radii 7-40 kpc) and bright (M_R=-23.2 to -24.6) elliptical galaxies, whose surface brightness distribution can be described by a single power law I(r)∝r^–β with β=0.10-0.36 to an accuracy of ∼0.2 mag. The isophotes of the host galaxies are found to be ellipses with no apparent ``boxyness'' or ``diskyness.'' The host galaxies of Mrk 501 and 1ES 2344+514 also exhibit a position angle twist that increases linearly with distance from the nucleus.

Using the two-dimensional photometric decomposition we have constructed tables of host galaxy magnitude as a function of measuring aperture diameter and seeing. These tables can be used to ``clean'' photometric data of the host galaxy contribution.