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Astron. Astrophys. 352, L17-L21 (1999)


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Letter to the Editor

Imaging and spectroscopy with FORS1 in the field of Q 0307-0015 * **

K. Jäger 1, K.J. Fricke 1, I. Appenzeller 2, T. Szeifert 2,4, J. Heidt 2, W. Gässler 3, R. Häfner 3, W. Hummel 3, B. Muschielok 3, H. Nicklas 1, W. Seifert 2 and O. Stahl 2

1 Universitäts-Sternwarte, Geismarlandstrasse 11, 37083 Göttingen, Germany (jaeger@uni-sw.gwdg.de)
2 Landessternwarte Heidelberg, Königstuhl, 69117 Heidelberg, Germany
3 Universitätssternwarte München, Scheinerstrasse 1, 81679 München, Germany
4 ESO Santiago, Alonso de Cordova 3107, Santiago 19, Chile

Received 12 August 1999 / Accepted 7 October 1999

Abstract

We present VLT-observations of a recently detected galaxy cluster candidate in the field of the radio-quiet quasar Q 0307-0015. R-band images and multi-object spectra (MOS) have been obtained during the commissioning phase II of FORS1 in December 1998. The presumed central cluster galaxy shows the typical spectrum and surface brightness profile of an early-type galaxy and has a redshift of z[FORMULA]0.396. We measured the redshift of 20 galaxies in the [FORMULA] [FORMULA] [FORMULA] field and found further 11 galaxies with similar redshift implying that we see a galaxy cluster at intermediate z. We estimate the cluster richness to be comparable with Abell class 0-1. The cluster is not physically associated with Q 0307-0015 having a redshift of z[FORMULA]0.770. This was to be expected considering the projected distance of [FORMULA]5´ on the sky.

A closer look at the immediate sourrounding of the QSO shows that Q 0307-0015 seems to reside in an unspectacular environment. Neither a definite close companion candidate nor any excess population of faint galaxies can be seen. This is consistent with the finding at low redshift that most radio-quiet QSOs reside in poorer environments than their radio-loud counterparts.

Key words: galaxies: active – galaxies: clusters: general – galaxies: quasars: individual: Q 0307-0015

* Based on observations made with the VLT UT1, operated on Cerro Paranal (Chile) by the European Southern Observatory (ESO).
** Based on observations made with the 2.2m telescope of the German-Spanish Astronomical Centre at Calar Alto, operated by the Max-Planck-Institut für Astronomie (Heidelberg), jointly with the Spanish National Commission for Astronomy.

Send offprint requests to: K. Jäger (jaeger@uni-sw.gwdg.de)

© European Southern Observatory (ESO) 1999

Online publication: November 23, 1999

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