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Astron. Astrophys. 328, L17-L20 (1997)

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2. The NGC4235 pair

Fig. 1 shows the configuration of the three bright X-ray sources in the NGC4235 field. The pair of AGN's are aligned within about [FORMULA] and their distances from the center deviates from the mean by only 8%. The average background density of X-ray sources has been measured by Hasinger et al. (1993 with a revision at the bright end, 1997 in preparation) with the same ROSAT PSPC in the same 0.5 - 2.0 keV band. The density is too small to explain such a pair as coincidence, especially since no other, unaligned X-ray sources are present. The apparent magnitudes and redshifts of the two AGN's are as catalogued by Hewitt and Burbidge (1993) and Véron-Cetty and Véron (1996).

[FIGURE] Fig. 1. A 19.4 ks exposure with the ROSAT PSPC. The central galaxy is an X-ray point source but the optical image is outlined approximately to scale to show the position of the minor axis. The X-ray counts per ks for the three bright sources are marked followed by the optical identification of the object and its redshift. The plus sign indicates the position of a V = 16.3 mag. Seyfert 1 of redshift z =.080. Note that the point spread function for the photons broadens appreciably off axis.
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© European Southern Observatory (ESO) 1997

Online publication: March 26, 1998