3 Results

The main results of this paper are given in Table 1 (with structure identical to Table 1 in Paper III) as follows: Column 1: CGCG (Zwicky et al. 1961-68) or VCC (Binggeli et al. 1985) denomination.
Column 2: NGC/IC names.
Columns 3, 4: adopted (1950) celestial coordinates, measured by us or taken from NED, with few arcsec uncertainty.
Column 5: "aggregation'' parameter. This parameter defines the membership to a group/cluster/supercluster: CSisol, CSpairs, CSgroups indicate members of the Coma Supercluster (5000 < V < 8000 kms^-1); CSforeg means objects in the foreground of the Coma Supercluster (V < 5000 kms^-1) and CSbackg means objects in the background of the Coma Supercluster (V > 8000 kms^-1). Galaxies in the Virgo region are labelled following the membership criteria given by Binggeli et al. (1993): VCA, VCB, VCM, VCW, VCW', VCSE, VCmem, are members to the cluster A or B, to the M, W, W' or South-East clouds or are not better specified members to the Virgo cluster respectively. NOVCC are galaxies taken from the CGCG in the outskirts of Virgo, but outside the area covered by the VCC. VCback are galaxies in the background of the Virgo cluster (V>3000 km s^-1). Members to the A262 and Cancer clusters are indicated.
Column 6: photographic magnitude as given in the CGCG or in the VCC.
Columns 7, 8: for CGCG galaxies these are the major and minor optical diameters (a₂₅, b₂₅) (in arcmin) derived as explained in Gavazzi & Boselli (1996). These diameters are consistent with those given in the RC3. For VCC galaxies the diameters are measured on the du Pont plates at the faintest detectable isophote, as listed in the VCC.
Column 9: morphological type.
Column 10: number of frames $N_{\rm f}$ combined to form the final image (depending on the adopted mosaic).
Column 11: number of elementary observations (coadds) $N_{\rm c}$. The total integration time (in seconds) is the product of the number of coadds $N_{\rm c}$ times the number of combined frames $N_{\rm f}$ times the on-chip integration time $t_{\rm int}$ which was set to 1 s.
Column 12: seeing (in pixels, with 1.61 arcsec per pixel).
Column 13: adopted zero point (mag/s).
Column 14: observing date (day-month-1997).
Column 15: $H_{\rm B25}$ magnitude obtained extrapolating the present photometric measurements to the optical diameter along circular apertures as in Gavazzi & Boselli (1996).
Column 16: $H_{\rm B25}^{\rm c}$ magnitude computed at the optical diameter (see Col. 15) corrected for galactic and internal extinction following Gavazzi & Boselli (1996). The adopted internal extinction correction is $\Delta m=-2.5 \, D\, \log(b/a)$ where D=0.17, as determined in Boselli & Gavazzi (1994).
Column 17: $H_{\rm T}$ total H magnitude extrapolated to infinity (see Paper V, Gavazzi et al. 2000b).
Column 18: galaxy observed major (r_H(20.5)) radius (in arcsec) determined in the elliptical azimuthally-integrated profiles as the radii at which the surface brightness reaches 20.5 H-mag arcsec^-2. Galaxies which require an extrapolation larger than 0.5 mag to reach the $20.5^{\rm th}$  magnitude isophote are labelled -1.
Column 19: the model-independent concentration index $\rm C_{31}$ as defined in de Vaucouleurs (1977) is the ratio between the radii that enclose 75% and 25% of the total light $H_{\rm T}$.

3.1 The virtual aperture photometry

The present data were compared with aperture photometry available in the literature by integrating the counts in concentric circular rings around the galaxy centres to provide curves of growth up to the diameter of the reference photometry. This comparison provided a general check of the intrinsic photometric accuracy of the current work. The virtual photometry measurements obtained in this work are compared with the aperture photometry available in the literature (200 measurements) in Fig. 3: on the average we find:

$H_{\rm this~work} - H_{\rm literature} = -0.013$ $\pm$ 0.107 mag.

A conservative estimate of the overall photometric accuracy of our data, including systematic errors on the zero point, is thus $\leq$ 0.1 mag.

Figure 3: The comparison between the present photometric measurements and those available from the literature as a function of the normalized aperture

The measurements taken through the individual "virtual circular apertures" are given in Table 2 (available only in digital format) as follows:
Column 1: Galaxy denomination in the CGCG (Z) or VCC catalogues.
Column 2: aperture diameter in arcsec.
Column 3: logarithmic ratio of the adopted aperture diameter to the optical a₂₅ diameter.
Column 4: integrated H magnitude within the aperture.

   

Table 2: The "virtual aperture photometry". This is a one page sample. The entire table containing 2646 entries is only available in electronic format

Galaxy	Ap.	${\rm log} Ap/a_{25}$	H
	arcsec		mag
(1)	(2)	(3)	(4)
VCC 25	19.00	-1.00	10.95
VCC 25	19.30	-.99	10.94
VCC 25	29.00	-.82	10.55
VCC 25	38.60	-.69	10.30
VCC 25	48.30	-.59	10.14
VCC 25	58.00	-.51	10.06
VCC 25	67.60	-.45	10.01
VCC 25	77.30	-.39	9.99
VCC 25	86.90	-.34	9.97
VCC 25	96.60	-.29	9.95
VCC 25	106.30	-.25	9.94
VCC 25	115.90	-.21	9.94
VCC 25	125.60	-.18	9.93
VCC 25	135.20	-.15	9.93
VCC 58	19.30	-.99	12.39
VCC 58	29.00	-.82	11.82
VCC 58	38.60	-.69	11.49
VCC 58	40.60	-.67	11.44
VCC 58	48.30	-.59	11.24
VCC 58	51.80	-.56	11.16
VCC 58	58.00	-.51	11.04
VCC 58	67.60	-.45	10.90
VCC 58	77.30	-.39	10.80
VCC 58	86.90	-.34	10.73
VCC 58	96.60	-.29	10.66
VCC 58	106.30	-.25	10.61
VCC 58	115.90	-.21	10.56
VCC 58	125.60	-.18	10.52
VCC 58	135.20	-.15	10.48
VCC 58	144.90	-.12	10.46
VCC 58	154.60	-.09	10.45
VCC 58	164.20	-.06	10.44
VCC 58	173.90	-.04	10.43
VCC 73	12.90	-1.00	10.60
VCC 73	19.30	-.82	10.19
VCC 73	25.80	-.70	9.95
VCC 73	27.00	-.68	9.91
VCC 73	31.60	-.61	9.81
VCC 73	32.20	-.60	9.80
VCC 73	35.10	-.56	9.76
VCC 73	38.60	-.52	9.71
VCC 73	45.10	-.45	9.64
VCC 73	51.50	-.40	9.59
VCC 73	58.00	-.35	9.55

Figure 4: The distribution of the limiting surface brightness reached in the outer light profiles, as a function of the exposure time

Figure 5: The relation between the apparent major radius rH(20.5) as determined in the infrared (this work) and the optical rB determined in the VCC at the faintest detectable isophote. The solid line represents the relation rH(20.5) = 0.7 rB(25.0)

Figure 6: The dependence of the near-infrared concentration index C31 on H band luminosity

3.2 Radii r_H(20.5)

The lowest surface brightness reached in each image is given as a function of the integration time in Fig. 4 (see Paper III for a more comprehensive description of the meaning of "lowest surface brightness"). Although the present observations are deeper on average than the ones obtained at TIRGO, we decided for consistency to measure the H band radii at the same isophotal radius as in Paper III: i.e. at the 20.5 mag arcsec^-2 isophote.

The comparison between the isophotal B band radii and the infrared r_H(20.5) isophotal radii determined in this work is shown in Fig. 5. The B radii are those measured on the du Pont plates at the faintest detectable isophote, as listed in the VCC. These are on average larger by 25% than the standard r_B(25.0) (Binggeli et al. 1985). Thus it is not surprising that the relation r_H(20.5) = 0.7 r_B used in Paper III (and reproduced as a solid line in Fig. 5) does not hold with the present data-set.

3.3 Magnitudes ($H_{\rm T}$, $H_{\rm B25}$)

$H_{\rm B25}$ magnitudes listed in Col. 15 of Table 1 are obtained by extrapolating the circular aperture measurements to the optical r_B(25.0) radius using standard growth curves (as in Gavazzi & Boselli 1996). $H_{\rm T}$ mag instead are obtained by extrapolating to infinity the magnitude integrated along elliptical isophotes using combinations of exponential and de Vaucoulers laws (see Gavazzi et al. 2000b: Paper V). As expected, $H_{\rm T}$ are brighter than $H_{\rm B25}$ by $0.05\pm0.15$ mag on average.

3.4 Concentration index (C₃₁)

The concentration index C₃₁ is a measure of the shape of light profiles in galaxies, independent of a (model-dependent) bulge-disk decomposition. Values larger than ( C₃₁>2.8) indicate the presence of substantial bulges.

We confirm the presence in our sample of a general correlation between C₃₁ and the H band (total or H₂₅) luminosity (computed from the redshift distance). We find that C₃₁ generally increases toward higher absolute magnitudes (Fig. 6). High C₃₁ are found only among high luminosity systems, but the reverse is not true: there are several high luminosity systems (namely late type spirals) with no or little bulge ( $C_{31}\sim 3$).