Optical off-nuclear spectra of quasar hosts and radio galaxies

We present optical (similar to 3200 to similar to 9000 Angstrom) off-nuclea r spectra of 26 powerful active galaxies in the redshift range 0.1 less tha n or equal to z less than or equal to 0.3, obtained with the Mayall and Wil liam Herschel 4-m class telescopes. The sample consists of radio-quiet quas ars, radio-loud quasars (All with -23 greater than or equal to M-V greater than or equal to -26) and radio galaxies of Fanaroff-Riley Type II (with ex tended radio luminosities and spectral indices comparable to these of the r adio-loud quasars). The spectra were all taken approximately 5 arcsec off-n ucleus, with offsets carefully selected so as to maximize the amount of gal axy light falling into the slit, whilst simultaneously minimizing the amoun t of scattered nuclear light. The majority of the resulting spectra appear to be dominated by the integrated stellar continuum of the underlying Salar ies rather than by light from the non-stellar processes occurring in the ac tive nuclei, and in many cases a 4000-Angstrom break feature can be identif ied. The individual spectra are described in detail, and the importance of the various spectral components is discussed. Stellar population synthesis modelling of the spect ra will follow in a subsequent paper.