1999A&A...352L..11H

We present imaging of the host galaxies of H 0414+009 and OJ 287 taken during the commissioning phases of FORS1 at the VLT-UT1. The host galaxy of H 0414+009 is well resolved in R and I, and marginally resolved in B. Based on our 2-dimensional modelling, it is a large and very luminous elliptical galaxy (M_R=-24.6, r_e=35kpc) with colours commonly found in elliptical galaxies (B-R∼1.45 and R-I∼0.45). The results are consistent with previous findings. The host galaxy of OJ 287 is marginally resolved. A de Vaucouleurs profile is slightly preferred over a disk-type profile. If true, the host galaxy is luminous (M_R=-23.4), compact (r_e=4.4kpc) and has a small offset to the south with respect to the active nucleus. This is consistent with the results obtained by Sillanpaeae et al. (1999, Host galaxies and environment of BL Lac objects. In: Takalo L.O., Sillanpaeae A. (eds.)), but different to the findings by Wurtz et al. (1996ApJS..103..109W) and Yanny et al. (1997ApJ...484L.113Y). The analysis of the marginally resolved host galaxies was complicated by a point spread function (PSF) varying across the field. Consequently, better results were obtained when using a PSF which varies with field position as compared to a constant PSF. This is possible as long as a sufficient number of stars is present on the images. Masking the central regions mostly affected by the PSF errors may also improve the results. Based on our experience we describe precaution which has to be taken for FORS1 observations and subsequent analysis of marginally resolved targets such as AGN host galaxies or planetary nebulae around young stellar objects.