Astron. Astrophys. Suppl. Ser. 134, 59-73

The central region of the Fornax cluster

I. A catalog and photometric properties of galaxies in selected CCD fields

M. Hilker ^1,4 - M. Kissler-Patig ^1,2,3 - T. Richtler ¹ - L. Infante ⁴ - H. Quintana ⁴

Send offprint request: M. Hilker

1 - Sternwarte der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
2 - UCO/Lick Observatory, University of California, Santa Cruz, CA 95064, U.S.A.
3 - Feodor Lynen Fellow of the Alexander von Humboldt Foundation
4 - Departamento de Astronomía y Astrofísica, P. Universidad Católica, Casilla 104, Santiago 22, Chile

Received March 23; accepted July 7, 1998

Abstract:

We present a photometric catalog (based on V and I photometry) of galaxies in the central regions of the Fornax galaxy cluster. Our 11 CCD fields cover 0.17 square degrees in total. The limiting surface brightness is around 24 mag arcsec^-2, similar to that of Ferguson's (1989) catalog, whereas our limiting total magnitude is around $V\simeq22$ mag, about two magnitudes fainter. It is the surface brightness limit, however, that prevents us from detecting the counterparts of the faintest Local Group dwarf spheroidals. The photometric properties of all objects are presented as a catalog (Appendix A). The properties and fit parameters of the surface brightness profiles for a sub-sample are presented as a second catalog (Appendix B)¹.

We can only add 4 new dwarf galaxies to Ferguson's catalog. However, we confirm that the dwarf galaxies in Fornax follow a similar surface brightness - magnitude relation as the Local Group dwarfs. They also follow the color (metallicity) - magnitude relation seen in other galaxy clusters. A formerly suspected excess of dwarf galaxies surrounding the central giant cD galaxy NGC 1399 can finally be ruled out.

An enhanced density of objects around NGC 1399 can indeed be seen, but it appears displaced with respect to the central galaxy and is identified as a background cluster at z=0.11 in Paper II of these series, which will discuss spectroscopic results for our sample.

Key words: galaxies: clusters: individual: Fornax cluster -- galaxies: fundamental parameters -- galaxies: photometry -- catalogs -- galaxies: dwarf