All observations have been conducted with the SAO RAS 6m telescope during the period 1996-2000. Besides candidate companion galaxies, three SBS BCGs were also observed. For one of them (SBS 1413+495) the redshift was unknown before, and for two others we tried to improve the accuracy of redshifts to make more confident our search for companions. This optical redshift for SBS 1413+495 was later confirmed and its precision was improved using HI data by Thuan et al. (1999). Candidate neighbours for two additional BCGs not entering into the sample of 86 BCGs were also observed, and appeared to be real companions (SBS 0916+542 and 1120+586). Observational results on these two new galaxies are given as well in Table A.1.
Three set-ups were used for the observations:
Since these observations were performed mainly as a back-up program, in most of the cases the conditions were not photometric. Our main goal was to get radial velocity of the studied candidates. Therefore we discuss only this parameter.
Reduction was done as follows.
Cosmic ray hits removal was done in MIDAS.
The standard procedures of debiasing,
flatfielding, wavelength and flux calibration were done in
IRAF.
Standard routines IDENTIFY, REIDENTIFY, FITCOORD, TRANSFORM were used
to do the
wavelength calibration and the correction for distortion and tilt for
each frame. Then the one-dimensional spectra were extracted from each
frame using the APALL routine without weighting.
To derive the
instrumental response function, we fitted the observed spectral
energy distribution of the standard stars with a high-order
polynomial.
Final measurements of the line intensities and positions and radial velocities were done in MIDAS. To improve the accuracy of the redshift determination, and further, to reduce possible small systematic shifts in the zero point of the wavelength calibration, we additionally checked the wavelengths of the night sky emission lines on the 2D spectra at the position of the object spectrum.
The objects observed are listed in Table A.1 containing
the following information:
Column 1: The object's IAU-type name.
Column 2: Right ascension (RA) for equinox B1950.
Column 3: Declination for equinox B1950.
Column 4: Apparent B-magnitude from APM database
(Irwin 1998) which was recalculated to standard
CCD B-magnitude using the calibration suggested by Kniazev et al.
(2001b). Its rms uncertainty is 0
45 over
the magnitude range
to
.
Column 5: Heliocentric velocity and its rms uncertainty in km s-1.
Column 6: Absolute B-magnitude calculated from the apparent B magnitude
and the heliocentric velocities. No correction for galactic extinction
is made because all observed objects are located at high galactic latitudes
and because the corrections are significantly smaller than the uncertainties
of the magnitudes.
Column 7: Preliminary spectral classification type according to
the presented spectral data. BCG/H II means that the galaxy
possesses a characteristic H II-region spectrum and a low enough
luminosity (
). SBN are spiral galaxies of lower
excitation with the central SF
burst and the corresponding position in the line ratio diagrams, as
discussed, e.g., in Ugryumov et al. (1999).
Seyfert galaxies are separated mainly on the diagnostic diagrams as AGN.
The criterion of broad lines was also used for the Sy classification.
The ELG type means that an object has emission lines but is difficult
to be classified using the existing data.
ABS means a galaxy with the detected and identified absorption lines.
Column 8: One or more alternative names
according to the information from NED.
Column 9: The list of spectral lines, well detected in the object
spectrum and used for classification and/or redshift measurement.
All observed spectra are shown in Figs. A.1-A.3.
Acknowledgements
We are pleased to thank T. Kniazeva for the help in the reduction of observational data and D. Makarov for consultations. Our thanks to K. Noeske for sending us his and co-authors' article prior publication, and to J. Schombert, who kindly provided us with some unpublished data on the LSB galaxy sample. The authors thank the anonymous referee for useful suggestions. We acknowledge the partial support from Russian state program ``Astronomy'' and Center of Cosmoparticle Physics "Cosmion". This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. The use of the Digitized Sky Survey (DSS-II) and APM Database is gratefully acknowledged.
Copyright ESO 2001