Table 2 (click here) gives an overview of the content of this catalogue. Column 2 gives the exposure times of the CCD fields used, and Col. 3 indicates the size of the stellar psf (major, minor axis) on these frames. Column 4 gives the magnitude limits at which the sample can be considered complete. These limits were derived from the comparison of plots of the number of EO's versus magnitude (see Fig. 5 (click here)) with R band galaxy counts by Metcalfe et al. (1991). Some entries for the completeness magnitude in Table 2 (click here) are marked as uncertain, caused by a small count of EO's, or by a magnitude distribution that is inconclusive. Corresponding completeness limits at V magnitudes are about 0.3 mag deeper.
Figure 5: Distribution of R magnitudes in the field
of
NGC 3226/7 among identified extended objects (solid line) and stellar
objects (dashed line)
Column 5 gives the size of the field (size of CCD-field minus size of the central interacting galaxy) to which the number counts in the following columns refer to. In Cols. 6 and 8, the measured counts of extended (EO) and Stellar Objects (SO) are given for each field, as well as (second number in these columns) the counts of these objects within the catalogue's completeness limit.
Also in Table 2 (click here), the numbers of expected background galaxies (Col. 7) and stars (Col. 9) within the fields' completness limits are given. The expected numbers of background galaxies were computed from the galaxy counts by Metcalfe et al. (1991). The errors in the expected galaxy counts are larger than given by Poisson statistics due to the clustering of galaxies. We based these errors on a calculation of the angular 2-point correlation function for the size of our CCD field, following the precepts of Roche et al. (1993). Since the completeness magnitudes of our catalog were derived by a comparison with Metcalfe et al.'s (1991) galaxy counts, it is no surprise that these counts roughly agree. We note however, that in most fields there are more objects then expected about 1-2 magnitudes below the completeness limit (i.e. in the range R= 18 - 19.5).
The counts of expected background stars were computed with a Galactic
population model (Bienayme et al. 1987,
Robin et al. 1996)
that is available online at
http://www.obs-besancon.fr/www/modele/modele_ang.html. The star
counts in our catalogue are generally somewhat higher than predicted
by this model. This is expected, as all ambiguous objects (whose psf
was somewhat larger then the stellar psf, but too small to be clearly
identified as EO) were included within the catalogue's stellar count,
N(SO), to which they contribute about
. In fields of the
more nearby central galaxies, such as
NGC 3226/7, Globular Clusters
may contribute to the total number of SOs, but their low
brightness would exclude them from the SOs within the completeness
limits.
In Fig. 5 (click here) we note the difference in the magnitude distribution function of SOs and of EOs. In general, the SO distribution is very similar across all the fields, whereas the magnitude distribution of EOs varies strongly among the different fields. The interpretation of the galaxy and star counts will be the topic of a forthcoming paper.
A compilation of parameters of the EOs is given in the catalogue's main tables (Tables 4-15), which are available in electronic form at CDS. Each table corresponds to one CCD-field. As an example, the first lines of electronic Table 12, listing the identified EOs within the field of NGC 3226/7, are shown in Table 3 (click here).
The columns in Tables 4-15 are:
Column 1: Identification number of the EO.
Columns 2 & 3: Size of the EO, giving the elliptical fitting values 
, in arcseconds.
Column 4: Position angle of the major axis, in degrees.
Columns 5 & 6: V magnitude and its error. 99.99 indicates unreliable photometry. -99.99 indicates an oversaturated object.
Columns 7 & 8: R magnitude and its error. 99.99 indicates unreliable photometry. -99.99 indicates an oversaturated object.
Columns 9 & 10: Position 
,
relative to the reference point (see Table 1) in arc seconds.