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Sample selection

The sample of Seyfert 2 galaxies was defined by Heckman et al (1995) based on the brightness of the Seyfert nucleus. Using the compilation of Whittle (1992), the 30 brightest Seyfert 2 were selected using the [OIII] 5007+4959 emission line flux and the monochromatic flux (nuFnu) of the nuclear non-thermal radio source at 1.4 GHz. All of them satisfy at least one of the two following criteria: log F([OIII])>=-12.0 (erg cm-2 s-1) and log F(1.4GHz)>=-15.0 (erg cm-2 s-1). The sample was restricted to the 20 cases with existing IUE data. The criteria used guarantees that the sample is unbiased with respect to the presence or absence of a nuclear starburst. The targets and properties are summarized in Table 1 of Heckman et al (1995). NGC 1068 was omitted from the sample used by Heckman et al to form the IUE spectral template, since it would otherwise have dominated the template (which weighted spectra based on the square of their signal-to-noise ratio).

We have taken ground-based optical spectroscopy of all the targets accessible with the 4m telescope at Kitt Peak National Observatory. HST UV images have been obtained for 12 of the 20 Seyfert 2 nuclei using the Faint Object Camera (FOC). We have also obtained UV spectra of 4 of these 12 Seyfert 2 nuclei with the HST Goddard High Resolution Spectrometer (GHRS). These are: Mrk 477, NGC 7130 (IC 5135), NGC 5135 and IC 3639 (Tol1238-364). They were chosen from the subsample of 12 Seyfert 2 nuclei for having the highest UV flux on arcsec scales. The results for Mrk 477 have already been presented by Heckman et al (1997) and a summary of the results is presented in this section. Here we present the UV images, UV spectroscopy, and optical spectroscopy of the other three galaxies. HST WFPC2 images, retrieved from the HST archive, are also included. In the following subsections we present a summary of the characteristics of these galaxies. Table 1 lists some properties of these galaxies.
 


 
next up previous
Next: NGC 7130 Up: Ultraviolet-Optical observations of the Previous: Introduction 
Rosa Gonzalez

1998-06-20