EDP Sciences
Free access
Volume 412, Number 3, December IV 2003
Page(s) 651 - 655
Section Galactic structure and dynamics
DOI http://dx.doi.org/10.1051/0004-6361:20031519

A&A 412, 651-655 (2003)
DOI: 10.1051/0004-6361:20031519

Optical spectroscopy of BL Lac objects: New redshifts and mis-identified sources

N. Carangelo1, 2, R. Falomo3, J. Kotilainen4, A. Treves2 and M.-H. Ulrich5

1  Università di Milano-Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
2  Università dell' Insubria, via Valleggio 11, 22100 Como, Italy
    e-mail: treves@uninsubria.it
3  Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy
    e-mail: falomo@pd.astro.it
4  Tuorla Observatory, University of Turku, Väisäläntie 20, 21500 Piikkiö, Finland
    e-mail: jarkot@astro.utu.fi
5  European Southern Observatory, ESO Headquarter Garching, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
    e-mail: mhulrich@eso.org

(Received 23 January 2003/ Accepted 12 June 2003)

We are carrying out a multi-purpose program of high signal to noise optical spectroscopy at medium resolution of 30 BL Lac objects. Here we report the detection of three new redshifts, and the discovery of three misclassified sources. The new redshifts refer to PKS 0754+100 ( z=0.266), H-1914-194 ( z=0.137) and 1ES0715-259, for which we derive a redshift of  z=0.465 and also a "new" classification a Steep Spectrum Radio Quasar. In two cases (UM493 and 1620+103) stellar spectra indicate a wrong classification. The three sources with new redshift measurement show strong [OIII] emission in their spectra and their host galaxy properties are known. The central black hole masses derived using the $M_{\rm BH}-L_{\rm bulge}$ and the $M_{\rm BH}$- $\sigma$([OIII]) relations are compared.

Key words: galaxies: BL Lacertae objects: general -- galaxies: active -- galaxies: quasars: general

Offprint request: N. Carangelo, nicoletta.carangelo@mib.infn.it

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© ESO 2003