Bibcode
DOI
Sbarufatti, B.; Treves, A.; Falomo, R.; Heidt, J.; Kotilainen, J.; Scarpa, R.
Referencia bibliográfica
The Astronomical Journal, Volume 132, Issue 1, pp. 1-19.
Fecha de publicación:
7
2006
Número de citas
90
Número de citas referidas
77
Descripción
We report on ESO Very Large Telescope optical spectroscopy of 42 BL
Lacertae objects of unknown redshift. Nuclear emission lines were
observed in 12 objects, while for another six we detected absorption
features due to the host galaxy. The new high signal-to-noise ratio
spectra therefore allow us to measure the redshift of 18 sources. Five
of the observed objects were reclassified as either stars or quasars,
and one is of uncertain nature. For the remaining 18 the optical spectra
appear without intrinsic features in spite of our ability to measure
rather faint (equivalent width ~0.1 Å) spectral lines. For the
latter sources a lower limit to the redshift was set, exploiting the
very fact that the absorption lines of the host galaxy are undetected in
the observed spectra.