9 The catalog

9.1 Description of the catalog

The catalog of galaxies which is described here is the first of a series which will be released during the progression of the survey. At the end of the survey a deeper and complete catalog will be produced at PDAC. The present one, is necessarily limited to the first observations (one year).

The catalog contains 20260 galaxies. Among them 14518 are new galaxies while 5742 are galaxies already present in LEDA.

Each galaxy is numbered with a provisional internal number (RED, for Rapid Extraction from DENIS), and an identifier from the LEDA database (PGC/LEDA). Galaxies are also identified with an alternate name taken in the following catalogues: NGC, IC (Dreyer 1988), UGC (Nilson 1973), ESO (Lauberts 1982), MCG (Vorontsov-Velyaminov et al. 1962-1974), CGCG (Zwicky et al. 1961-1968), IIZW, IIIZW, VIII from the catalog of compact and eruptive galaxies (Zwicky 1971), IISZ (extension of the same list by Rodgers et al. (1978), FAIR (Fairall 1977-1988), HICK (Hickson 1989), KUG (Takase & Miyauchi-Isobe 1984-1989), IRAS (IRAS), MK (Markarian 1971-1977), UM (University of Michigan list, MacAlpine et al. 1981). The detailed references to these catalogs are given in Paturel et al. (1989). Two additional catalogs are included: Saito et al. (1990-1991) and Dressler (1980). The notations for corresponding galaxy names are SAIT (e.g. SAIT 69-1, for object 69 in list 1 of Saito et al.) and DRCG (e.g., DRCG 39-41, for galaxy 41 in cluster 39, the numbering of clusters is made according to the order in the original publication).

For each galaxy, the catalog gives the weighted mean parameters obtained as described in the previous section. Actual mean errors $\sigma$ are calculated according to Paturel et al. (1996) using individual mean errors deduced in previous section. For I-band magnitudes the mean error is taken as a function of the magnitude itself. An estimate made from Fig. 10 gives: $\sigma (I) = 0.05B\rm _T-0.51$. The weights used for calculating the weighted means are the inverse square of actual mean errors. For nights suspected to be of poor photometric quality the actual mean error is divided by 3. Further, when the quality of the matrix is uncertain ("peculiar", "multiple" or "truncated"), the weight is divided by 2. This correcting coefficient is deduced from the comparison of I magnitudes with poor quality objects.

The quality of each individual matrix is coded as follows: "Normal" galaxies are coded as 1, "Peculiar" galaxies as 10, "Multiple" as 100 and 'Truncated' as 1000. This code is added for each measurement. So, the resulting code gives immediately the number of independent measurements (sum of digits) and the quality of each of them. For instance, the code 1002 means that there are one truncated matrix and two normal ones (i.e., 3 independent measurements). "Truncated" means an overestimated magnitude, on the contrary, "Multiple" means that the magnitude of the considered galaxy is underestimated.

  

Figure 16: Distribution of the 20260 galaxies of the present DENIS catalog presented with a Flamsteed's equal area projection in equatorial (2000) coordinates

The different columns are the following:

• Column 1: Provisional DENIS identifier. This identifier is just an internal number given for easy identification. This number will be replaced by an appropriate final DENIS number.
• Column 2: LEDA identifier. This number allows rapid retrieval in the LEDA database. This number is identical to the PGC number for LEDA number less than 73197.
• Column 3: Alternate name according to a hierarchy: NGC, IC, ESO, UGC, MCG (see text above).
• Column 4: Equatorial coordinates for epoch 2000, in hours, minutes, seconds and tenths for the Right Ascension and in degrees, arcminutes and arcseconds for the declination. The actual mean error on the position of the galaxy is given in the same column, next line in arcseconds.
• Column 5: Total I-band magnitude I(DENIS) with its mean error on the second line.
• Column 6: Isophotal diameter in log scale $\log D$(DENIS), where D is in 0.1 arcmin following the notation of de Vaucouleurs et al. (RC1, RC2). The actual mean error is given on the second line.
• Column 7: Isophotal axis ratio in log scale $\log R$(DENIS), where R is the ratio of the major to the minor axis. The actual mean error is given on the second line.
• Column 8: Position angle $\beta$(DENIS) in degrees, measured from North Eastwards. Its value lays between and 180 degrees (excluding 180). For $\log R$(DENIS) < 0.5 the meaning is poor. This is reflected by the actual mean error given on the second line.
• Column 9: Photometric morphological type code T(DENIS). The coding is given according to RC2 (i.e. T from -5 to 10 for Elliptical to Irregular galaxies). The mean error is given on the second line.
• Column 10: Quality code of the object (1000 = truncated object, 100 = multiple object, 10 = peculiar object, 1 = normal galaxy). The sum of digits gives the number of independent measurements.

A sample page is given at the end of the paper. The catalog is available in electronic form at PDAC and Lyons Observatory.

9.2 Distribution on the sky

The distribution on the sky is given in equatorial coordinates for the epoch 2000 (Fig. 16). The strips are clearly visible. The zone called "Equatorial" ($\delta$between $+2\deg$ and $-28\deg$) is not so well covered because observations are avoided in this zone when Moon is bright or when the wind is strong. Further, many frames are rejected in this zone at the end of the strip (near $-28\deg$) because of the shift in header-coordinates. No attempt is made to reach low galactic latitudes. This is done independently in J and K bands.

9.3 Completeness limit

If we assume a homogeneous distribution of galaxies ($N \propto r^{3}$), the plot of the number of galaxies (in log scale, i.e. $\log N$) brighter than a given magnitude limit $I_{\rm limit}$versus this magnitude limit should be linear with a slope of 0.6. This plot (Fig. 17) is quite linear up to $I_{\rm limit}= 14.5$with a slope of $0.62 \pm 0.02$.The sense of this completeness limit must be explained. It means that in surveyed directions all galaxies brighter than 14.5 are detected. Because the sampling is made randomly and 1/4 of the survey is presented here, the completeness limit in apparent magnitude of this first DENIS catalog is $I_{\rm limit}= 14.5$.

  

Figure 17: Completeness curve. The completeness curve is quite linear up to the completeness limit $I_{\rm limit}= 14.5$. The slope ($0.62 \pm 0.02$, dashed line) is very nearly the one expected for a homogeneous distribution of galaxies (0.6)

 

Table 1: Sample page of the present catalog

Acknowledgements

This work would have been impossible without the collaboration of M.C. Marthinet, C. Petit, L. Provost, F. Gallet, R. Garnier, J. Rousseau. They are fully associated with this work. The DENIS team is warmly thanked for making this work possible and in particular the Operations team at la Silla. We thank also G. Mamon for careful reading of the article. The DENIS program is partly funded by the European Commission through SCIENCE and Human Capital and Mobility grants. It is also supported in France by INSU, the Education Ministry and CNRS, in Germany by the Land of Baden-Würtenberg, in Spain by DGICYT, in Italy by CNR, in Austria by the Fonds zur Förderung der Wissenschaft und Forschung, in Brazil by FAPESP.