2 The sample

The B2 sample of LLRGs comprises the samples by Colla et al. ([1975], hereafter C75) and Fanti et al. ([1978], herafter F78). Both samples are optically complete down to the limiting magnitudes of $m_{\rm pg}=15.7$ for C75, known as the "bright'' sample, and m_V=16.5 for F78, known as the "faint'' sample. A few galaxies on the "faint'' sample have V magnitudes in the range 16.5-17 mag. On the radio side the two samples are complete down to 0.25 Jy at 408 MHz, although fainter radio galaxies are listed down to 0.2 Jy. The average redshift for the "bright'' sample is 0.03 and the average radio power $P_{408} \sim 10^{24.2}$ W Hz^-1. The same parameters for the "faint'' sample are 0.09 and 10^25.1 W Hz^-1. Whereas that the "bright'' sample includes galaxies of all morphological types, only those classified as ellipticals were included in the F78 "faint'' sample.

High quality radio maps for most of the galaxies were obtained in a systematic way by the Bologna group using VLA configurations A,B and/or C, or their combination (Parma et al. [1986]; de Ruiter et al. [1986]; Fanti et al. [1986], [1987]; Morganti et al. [1987]). The sample was also subject to systematic studies of their radio cores (Feretti et al. [1984]; Giovannini et al. [1988]) and their IR properties (Impey & Gregorini [1993]). After removing eight misclassified galaxies the combined B2 sample comprised 115 galaxies (Fanti et al. [1987], hereafter F87). Parma et al. ([1987]) analysed from the available radio maps from the Bologna group and the literature the presence of radio jets, obtaining a subsample of 43 B2 radio galaxies with jets and a smaller subsample of 11 sources with ill-defined radio jets. The radio sources observed for this work include all but one (B2 1426+25) of the 72 galaxies in the B2 sample not classified by Parma et al. ([1987]) as having a well-defined jet. Surface photometry of a subset of 24 B2 radio galaxies with jets was previously reported by our group (González-Serrano & Pérez-Fournon [1989], [1991], [1992]; González-Serrano et al. [1993], hereafter Papers I-IV) and sources with jets in Parma et al. ([1987]) were deliberately excluded for the present work. An exception was the galaxy B2 0326+39 (not included in Papers I-IV), which was observed with the new sources due to scarcity of other targets at the right ascensions observable during the runs. Together with the data in Papers I-IV we have now obtained V-band optical CCD imaging for 83 per cent (96/115) of the B2 galaxies. In more recent works Parma et al. ([1993]) and Morganti et al. ([1997]) have analysed the presence of jets on the B2 galaxies using a whole set of VLA observations at various resolutions, including new unpublished data. From this analysis eight ill-defined jets have been now confirmed, another one was rejected (B2 1609+31) and three new radio jet sources were identified (B2 1615+32, B2 1833+32 and B2 0828+32).

 

 

Table 2: Flux levels on the V-band contour plots

B2 name	$\mu_{\rm sky}^{a}$	$\mu_{\rm first}$	$\Delta$mag	$\sigma$ level	seeing(arcsec)
0116+31	20.77	24.33	0.60	0.75	1.72
0120+33	20.71	24.92	0.60	1.00	1.85
0149+35	21.01	24.11	0.60	2.50	2.00
0207+38	21.00	23.88	0.60	3.00	1.96
0209+37	21.27	24.47	0.60	2.50	1.65
0222+36	21.05	24.13	0.60	2.50	1.94
0258+35	20.97	23.99	0.60	0.75	1.85
0326+39	20.95	25.06	0.60	1.00	1.69
0331+39	21.06	23.77	0.60	2.50	1.95
0648+27	20.77	23.95	0.60	1.00	2.16
0708+32	20.87	24.57	0.60	1.50	1.23
0722+30	20.89	24.24	0.60	2.00	2.21
0800+24	20.88	24.12	0.60	1.50	2.10
0828+32	21.04	23.81	0.60	1.00	1.45
0838+32	20.99	24.36	0.60	0.50	1.29
0843+31	20.86	24.56	0.60	1.50	1.89
0916+33	20.84	24.18	0.60	0.50	1.76
0922+36	21.01	24.08	0.60	2.50	1.12
0924+30	21.26	24.86	0.60	1.50	1.86
0944+39	20.29	24.38	0.60	1.00	2.35
1003+26	20.96	24.17	0.60	0.75	1.49
1003+35	21.01	24.64	0.60	1.50	1.10
1037+30	20.82	24.02	0.60	1.00	1.62
1039+27	21.16	24.50	0.60	2.00	2.14
1101+38	20.73	21.90	0.60	8.00	1.52
1102+30	20.99	24.32	0.60	0.50	1.13
1106+26	20.87	24.25	0.60	1.50	0.95
1113+24	20.93	24.62	0.60	1.50	1.63
1141+37	21.01	24.67	0.60	1.50	1.76
1144+35	20.80	24.21	0.60	2.00	1.38
1204+24	20.94	24.60	0.60	1.50	1.36
1204+34	21.15	24.59	0.60	1.50	2.56
1217+29	18.97	22.08	0.60	2.50	1.36
1251+27	21.05	24.34	0.60	1.50	0.99
1256+28	21.14	23.46	0.60	2.00	2.44
1257+28	21.14	23.94	0.60	2.50	1.34
1300+32	20.99	24.22	0.60	0.50	1.33
1303+31	21.02	24.33	0.60	2.00	1.44
1316+29	21.21	24.14	0.60	2.00	1.46
1317+33	21.07	23.51	0.60	1.50	1.64
1318+34	21.20	24.09	0.60	2.00	1.38
1339+26	21.09	23.78	0.60	2.00	1.70
1346+26	21.19	24.13	0.60	2.00	1.92
1347+28	21.41	24.23	0.60	1.00	1.27
1358+30	21.18	24.41	0.60	1.00	1.91
1422+26	21.41	24.27	0.60	2.00	1.26
1430+25	21.21	24.14	0.60	2.00	1.18
1441+26	21.10	24.04	0.60	2.00	1.68
1447+27	21.18	23.33	0.60	2.00	1.28
1455+28	21.42	24.27	0.75	2.00	1.26
1457+29	21.14	24.06	0.75	2.00	2.02
1502+26	21.03	23.32	0.60	1.50	1.02
1511+26	21.10	24.35	0.75	1.50	1.83
1512+30	21.43	24.59	0.60	1.50	1.31
1527+30	21.14	24.10	0.60	2.00	1.49
1557+26	21.09	24.34	0.60	0.50	1.45
1609+31	20.90	24.25	0.60	1.50	1.75
1610+29	21.14	24.10	0.60	2.00	1.36

 

Table 2: continued

B2 name	$\mu_{\rm sky}^{a}$	$\mu_{\rm first}$	$\Delta$mag	$\sigma$ level	seeing(arcsec)
1615+32	21.07	23.74	0.75	2.00	2.08
1615+35	20.92	24.26	0.60	1.50	1.31
1621+38	21.09	23.86	0.60	1.00	1.05
1626+39	21.08	23.92	0.60	1.00	1.29
1652+39	21.07	23.17	0.60	8.00	1.03
1657+32	21.18	24.14	0.60	1.00	1.37
1658+32	20.97	24.02	0.60	2.00	1.46
1726+31	21.02	24.33	0.75	1.50	1.13
1833+32	20.92	23.99	0.60	2.00	1.53
1855+37	20.91	23.53	0.60	2.00	1.23
2240+29	20.79	23.46	0.60	3.00	1.25
2257+25	19.20	22.67	0.60	0.50	1.26
2320+32	19.59	21.98	0.60	1.00	1.79
2335+30	20.86	24.48	0.60	0.50	2.03
a V mag arcsec-2.

The list of B2 galaxies studied in this work is presented in Table 1. Information is given on the names of the optical galaxy/radio source in other catalogues, position of the optical galaxy, radio power, redshift, presence of radio jets (from Parma et al. [1987], [1993] and Morganti et al. [1997]) and references for radio maps. Positions of the optical galaxies were taken from the original papers by C75 and F78, except for a few cases. For B2 1300+32 and B2 1422+26 we used the positions given by F87 and for B2 1141+37 that given by Giovannini et al. ([1988]). In two additional cases the positions were obtained from the CCD images, using as reference APM positions from POSS-I prints (Irwin [1992]). These sources are B2 0838+32, whose position in C75 corresponds to the mid point between two galaxy components and B2 1610+29, whose position in the same work has a rather large offset.

For a few B2 sources the original identification papers by C75 and F78 listed more than one optical galaxy that could be associated to the radio emission. In the series of papers on VLA observations by the Bologna group (F87 and references therein) the optical counterparts were identified more precisely as the resolution of the radio maps increased and from the detection of the radio cores. The optical galaxy listed in Table 1 for B2 1141+37 (one of the galaxies in a group of four) is different from that given by F87. In addition, there are four sources in Table 1 for which one of the tentative identifications given by the Bologna group is selected in our work (B2 0838+32, B2 1106+26, B2 1502+26 and B2 1511+26). The explanation of the selection of the optical galaxy in these cases is presented in next section. For the source B2 0843+31 we listed the same optical galaxy as that given by the Bologna group, although the identification is uncertain. The ambiguity in the identification was previously noted by de Ruiter et al. ([1986]) and F87. The identification of source B2 0916+33 with a bright galaxy appears to be erroneous. C75 identified the source with an irregular galaxy, and the source was not further studied by the Bologna group since their follow up radio observations were restricted to the elliptical galaxies. A bright spiral galaxy was identified with B2 1441+26 in C75, but this appears to be another misidentification (Parma, private communication). A description of the optical identification of these three radio sources is presented in the next section.

The redshifts listed in Table 1 were taken from C75 and F78, except for B2 1457+29, which was obtained in this work, and B2 1039+27, B2 1106+26, B2 1141+37, B2 1300+32, B2 1317+33, B2 1339+26 and B2 1502+26, whose redshifts were taken from the NASA/IPAC Extragalactic Database (NED).

The total radio power at 408 MHz was calculated using the total flux densities at 408 MHz given by C75, F78 and the revised values (for some sources) presented by Feretti et al. ([1984]) and Giovannini et al. ([1988]). An spectral index $\alpha = -0.7$ ( $S_\nu \propto \nu^{\alpha}$) was assumed to obtain the k-correction. The used expression was log P₄₀₈ = 24.20 + log S₄₀₈ + 2 log (z ( 1 + z/2)) - log (1 + z) $^{1+\alpha}$, being S₄₀₈ the total flux density at 408 MHz in mJy, z the redshift and P₄₀₈ the total radio power at 408 MHz in W Hz^-1.