R. Falomo et al., HOST GALAXY AND ENVIRONMENT OF THE BL-LACERTAE OBJECT PKS-0548-322 - OBSERVATIONS WITH SUBARCSECOND RESOLUTION, The Astrophysical journal, 438(1), 1995, pp. 9-10
We report on direct, subarcsecond resolution imaging of the nebulosity
and spectroscopy of galaxies in the field of the BL Lacertae object P
KS 0548-322. Surface photometry of the nebulosity is used to derive th
e properties of the host galaxy (M(v) = -23.4), which exhibits signs o
f interaction with a close companion galaxy at similar to 25 kpc. The
radial brightness profile of the nebulosity is well fitted by the cont
ribution of a bulge (r(1/4)) plus a point source and a small internal
disk. An analysis of the galaxies in the field shows that the source i
s located in a rich cluster of galaxies. Spectra of five galaxies in t
he field indicate that they are at the same redshift as the BL Lac obj
ect, thus supporting the imaging result of a surrounding cluster assoc
iated with the BL Lac. This cluster is most likely Abell S0549.