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The Southern Sky Redshift Survey
We report redshifts, magnitudes, and morphological classifications for5369 galaxies with m_B <= 15.5 and for 57 galaxies fainter than thislimit, in two regions covering a total of 1.70 sr in the southerncelestial hemisphere. The galaxy catalog is drawn primarily from thelist of nonstellar objects identified in the Hubble Space TelescopeGuide Star Catalog (GSC). The galaxies have positions accurate to ~1"and magnitudes with an rms scatter of ~0.3 mag. We compute magnitudes(m_SSRS2) from the relation between instrumental GSC magnitudes and thephotometry by Lauberts & Valentijn. From a comparison with CCDphotometry, we find that our system is homogeneous across the sky andcorresponds to magnitudes measured at the isophotal level ~26 magarcsec^-2. The precision of the radial velocities is ~40 km s^-1, andthe redshift survey is more than 99% complete to the m_SSRS2 = 15.5 maglimit. This sample is in the direction opposite that of the CfA2; incombination the two surveys provide an important database for studies ofthe properties of galaxies and their large-scale distribution in thenearby universe. Based on observations obtained at Cerro TololoInter-American Observatory, National Optical Astronomy Observatories,operated by the Association of Universities for Research in Astronomy,Inc., under cooperative agreement with the National Science Foundation;Complejo Astronomico El Leoncito, operated under agreement between theConsejo Nacional de Investigaciones Científicas de laRepública Argentina and the National Universities of La Plata,Córdoba, and San Juan; the European Southern Observatory, LaSilla, Chile, partially under the bilateral ESO-ObservatórioNacional agreement; Fred Lawrence Whipple Observatory;Laboratório Nacional de Astrofísica, Brazil; and the SouthAfrican Astronomical Observatory.
| Spectroscopy of the NGC 4782/3 Dumbbell Dominated Group of Galaxies: Dark Haloes and Merger of Subgroups
A nearly complete sample of new velocities for 96 galaxies covering anarea 1^deg^ x 1.25^deg^ centered on NGC 4782/3 are presented. Includingdata from the literature a total of 125 velocities are compiled. Wededuce that 40 galaxies are likely members of the group centered on NGC4782/3, more than doubling the original confirmed 13 members. Based onthis extended velocity sample we analyze the velocity structure of thisunusual group. A bi-modal velocity structure centered on each of thedumbbell components provides evidence for an ongoing collision of twosubgroups associated to these components. In velocity space the richersubgroup is centered on the more massive NGC 4782. From the subgroupdynamics we derive approximate dynamical masses of 5 x 10^13^ M_sun_ and1 x 10^13^ M_sun_ for the NGC 4782 and NGC 4783 subgroups, respectively.This leads to a group M/L ~ 300 (M/L)_sun_, implying that -90% of thegroup mass is in dark form, within subsystems associated to eachsubgroup. The colliding elliptical galaxies have massive haloes whichshould be important in shaping the outcome of the collision and mergerprocess. In particular, haloes could change the interpretation of thetidal distortions and play a role in the shaping of the radio doublebent jet structure of 3C 278.
| An image database. II. Catalogue between δ=-30deg and δ=70deg.
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
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