In selected fields in the Fornax cluster, located near ellipticals, more than 870 galaxies were identified down to a V magnitude of 22 mag. Photometric properties, such as total V magnitude, (V - I) color, peak and effective surface brightness, and effective radius of these galaxies are compiled in a catalog.
For a bright subsample of the galaxies we determined the seeing corrected true central surface brightnesses. Exponential and/or de Vaucouleur profiles were fitted to these data and their parameters are given in a further catalog (Appendix B). Only few galaxies could clearly be identified as dwarf galaxies by their location in the surface brightness magnitude diagram, where they follow the expected sequence for dwarf ellipticals. Most of them are already listed in the Fornax Cluster Catalog (Ferguson 1989). However, our survey limit of about 24 mag arcsec-2 in peak surface brightness is too bright to detect dwarfs like the faintest Local Group dwarf spheroidals, if they were located at the Fornax distance. On the other hand, among the high surface brightness objects compact dwarfs might be hidden, as shown by two nucleus-like objects that are Fornax members as derived from their radial velocities (see also Paper II).
The "n'' parameter of the Sérsic profile fits is clearly correlated to the absolute luminosity of the dwarf ellipticals in Fornax. The n-luminosity relationship seems to continue in the domain of "normal'' early-type galaxies.
In the color magnitude diagram the dwarfs tend to follow a color - magnitude relation in the sense that fainter galaxies are bluer. The common explanation for this relation is a decreasing metallicity with decreasing luminosity. However, for some dwarfs the blue colors might also be a hint for an existing young or intermediate-age stellar population, as it is seen in several Local Group dwarf spheroidals. Evident signs for recent and ongoing star formation in the center of the cluster can only be seen in the irregular galaxy NGC 1427A.
At fixed limiting magnitude the galaxy density strongly varies from field to
field. On average the density in most fields is comparable to the one in the
absolute background fields.
South and east of NGC 1399 we found a significant excess of galaxies as
compared to the other fields. However, an excess of dwarf galaxies surrounding
NGC 1399 can be ruled out, since nearly all of these galaxies belong to a
background cluster at z = 0.11. The brightest galaxy of this background
cluster possesses an extended cD halo and is located 
south of
NGC 1399.
The strong background galaxy fluctuations make the search for compact dwarfs
by a statistical subtraction of background objects meaningless.
The point sources in the central Fornax fields are not uniformly distributed
around NGC 1399. The peak of their density distribution is displaced about
east of the center of the galaxy. Assuming that most of them
are no background cluster members, but rather globular clusters, two
explanations seem to be possible: (1) the central globular cluster system
and the bulge of NGC 1399 are disentangled from each other and
follow different potentials, or (2) tidal tails of accreted globular clusters
from passing Fornax galaxies have temporarily squewed the distribution of
globular clusters.
We thank the referee H.C. Ferguson for his very useful comments which improved the paper. This research was partly supported by the DFG through the Graduiertenkolleg "The Magellanic System and other dwarf galaxies" and through grant Ri 418/5-1 and Ri 418/5-2. LI and HQ thanks Fondecyt Chile for support through "Proyeto FONDECyT 8970009" and from a 1995 Presidential Chair in Science.
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