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Up: A neutral hydrogen survey

Subsections

3 Observations and results

3.1 Nançay and Parkes H I line observations

The Nançay telescope is a meridian transit-type instrument of the Kraus/Ohio State design, consisting of a fixed spherical mirror, 300 m long and 35 m high, a tiltable flat mirror (200$\times$40 m), and a focal carriage moving along a 90 m long curved rail track, which allows the tracking of a source on the celestial equator for about 1 hour. Located in the centre of France, it can reach declinations as low as $-39^{\circ}$. It has an effective collecting area of roughly 7000 m2 (equivalent to a 94-m diameter parabolic dish). Due to the elongated geometry of the mirrors, at 21-cm wavelength it has a half-power beam width of $3'\,\hspace{-1.7mm}.\hspace{.0mm}6$ E-W$\times$ 22' N-S at declinations from $-38\mbox{$^\circ$ }$ to 15 $\mbox{$^\circ$ }$, and its HPBW in declination increases to 23' at $\delta=30\mbox{$^\circ$ }$, $25'\,\hspace{-1.7mm}.\hspace{.0mm}5$ at 50 $\mbox{$^\circ$ }$ and $32'\,\hspace{-1.7mm}.\hspace{.0mm}5$ at 70 $\mbox{$^\circ$ }$ (E. Gérard, private comm.). Typical system temperatures were $\sim$40 K for our project.

The observations at Nançay were made during several observing runs in the period of July 1995-July 1998, using a total of about 340 hours of telescope time. For a technical description of the Nançay decimetric radio telescope and the general methods for data handling and reduction see, e.g., Theureau et al. (1998) and references therein. Most objects were observed for about four 1-hour long periods; one hour being the typical maximum tracking time for the transit-type Nançay telescope. We obtained our observations in total power (position-switching) mode using consecutive pairs of two-minute on- and two-minute off-source integrations. Off-source integrations were taken approximately 20$^{\rm m}$ E of the target position. For objects with known redshifts the autocorrelator was divided into two pairs of cross-polarized receiver banks (H and V polarisation), each with 512 channels and a 6.4 MHz bandpass, and the centre frequencies of the two banks were tuned to the redshifted systemic H I velocity of the target measured in the Green Bank survey (Table 2), if known, or on the optical systemic velocity (Table 1), if not. Thus, the velocity coverage is about 1200 kms-1 with a velocity resolution of about 3.1 kms-1. For the determination of the H I line profile parameters and upper limits (see Table 2), the velocity resolution was degraded to 15.8 kms-1.


  \begin{figure}\psfig{figure=ds1681fig1a.ps,width=18cm}\end{figure} Figure 1: a) 21-cm H I line spectra of all polar-ring galaxies and polar ring galaxy candidates with previously known redshift observed at Nançay, and of PRC B-08, whose redshift was first measured in the present survey, as well as of PRC D-14, whose redshift was unknown when it was observed for the survey. Velocity resolution is 15.8 kms-1 for all spectra, except for PRC D-14, where it is 19.0 kms-1. Radial velocities are according to the radio convention

For the 8 objects that had no known redshift at the start of the Nançay survey (B-08, 10, 13, 14, 20, 23, 24, and D-14), the autocorrelator was divided into four slightly overlapping banks of 256 channels each. Thus, a search for H I line emission was made in the H polarization channel only, separately in two velocity ranges, 340-5207  kms-1 and 5140-10007 kms-1, respectively. The velocity resolution used for the determination of the profile parameters or upper limits (Table 3) was 19.0 kms-1; the two upper limits given in Table 3 for undetected objects of unknown redshift represent, respectively, the two aforementioned velocity search ranges. Subsequently, one object detected in this mode, B-08, was reobserved in the same way as the other objects with known redshift.

We reduced our H I spectra using the standard Nançay spectral line reduction packages available at the Nançay site. With this software we subtracted baselines (generally third order polynomials), averaged the two receiver polarizations, and applied a declination-dependent conversion factor to convert from units of $T_{\rm sys}$ to flux density in mJy. The $T_{\rm sys}$-to-mJy conversion factor is determined via a standard declination-dependent calibration relation established by the Nançay staff through regular monitoring of strong continuum sources. In addition, we applied a flux density scaling factor (see Matthews et al. 1998; Matthews & van Driel 2000) of 1.26 to our spectra based on statistical comparisons of our late-type spiral survey observations with other data. The reduced Nançay spectra are shown in Fig. 1.

In addition, three PRGs were observed and detected with the 64-m Parkes radiotelescope for our survey: B-01 (IC 51), B-19 (AM 2020-504) and B-21 (ESO 603-G21). Of these, B-19 is a southern object out of reach of the other 3 telescopes used for our survey, with no published H I data. The profile parameters derived for these objects are listed in Table 3.



 
Table 2: H I survey data for the combined polar ring galaxy H I sample
PRC H I Observations -- $V_{\rm HI}$ -- -- $\int$SdV -- -- $\Delta$V20 -- $\Delta$V50 rms
No. Telescope codes Nan GB Eff Nan GB Eff Nan GB Eff Nan Nan
  Survey Others [km s-1] [Jy km s-1] [km s-1] [km s-1] [mJy]

                         
Kinematically-determined polar-ring galaxies            

                         
A-01 E,G,N V 5537 5521 5670 2.07 3.82 3 360 408 310 346 2.2
A-02 G,N V 4596 4572   3.16 6.22   359 441   347 3.0
A-03 G E,G,G43,N,W   875     34.2     298      
A-05 G AT,P,V   2909     23.2     244      
A-06 E,G,N V,W 5424 5480 5423 4.94 16.4 7.3 343 354 214 314 2.9
B-03 N A,V --     <2.1     --       2.3
B-17 G A,N,W   1239     13.6     200      
B-21 E,G,N P 3165 3180 3449 4.95 14.3 17.2 286 272 355 251 2.6
C-13 G A,G,G43,N,W   848     187.8     325      
C-24 E,G,N A 6411 6410 6404 2.32 4.62 3 241 241 239 188 2.3
C-27 E,G A   1954 1968   7.93 7.4   196 177    
C-45 G P,R   524     300     570      

                         
Good candidates for polar-ring galaxies            

                         
B-01 E,G,N P 1715 1709 1728 9.1 11.5 9.4 242 253 236 169 2.6
B-08 N   2859     1.69     188     178 3.9
B-09 N,E   --   5856 <2.4   7 --   353   2.3
B-10* E,N   --     <2.8/2.6     --       2.7/2.5
B-11 E,G G   2769 2769   12.0 11.1 -- 173 156    
B-12 G,N   10481 --   1.46 <6.0   415 --   377 1.5
B-13* N   --     <4.6/4.6   -- --       3.6/3.6
A1254 N   --     <2.1     --       2.3
B-14* N   --     <4.5/5.0   -- --       3.5/3.9
B-16 E V     2842     5.4     386   2.2
B-20 N   --     <2.3/2.8     --       3.1/3.7
B-23 G,N P -- --   <4.3/3.2 <2.2   -- --     5.7/4.2
B-24 N   --     <2.9/2.1     --       2.9/2.8
B-27 G     --     <3.7     --      

                         
Possible candidates for polar-ring galaxies            

                         
C-06 N A --     <2.9     -- --     2.4
C-09 E,G,N   -- 5629 -- <2.4 1.53 <3.2 -- 302 --   2.3
C-11 G G43,P   394     37.4     113      
C-12 E,G,N   1162 1149 1152 0.87 1.64 3.6 143 174 152 117 5.4
C-14 G P   4775     26.2     678:      
C-18 G,N N 1753 1799   1.08 1.75   114 167   94 2.9
C-25 E,G,N   -- 3686 4037 <3.4 3.56 0.9 -- 397 250   3.8
C-26 E,G,N A   5811 5412 <2.8 3.96 4.3 -- 299 620   3.1
C-28 E,N G,E,J,W 1479   1478 34.39   54 313   140 291 4.8
C-29 E,G E   2772 2850   2.9 1.7   164 159    
C-30 E,N   12053   -- -1.2:   <2.7 189   -- 152 3.9
C-32 E,N   --   6639 <3.3   1.6 --   273   2.9
C-33 E,N   3560   3570 2.94   5 237   332 218 2.8
C-34 N A 903     1.47     93     41 2.1
C-35 E,G,N A 1173 -- 1526 2.97 <7.8 1.2 325: -- 322 175 1.8
C-37 E,G,N G 1228   1255 10.47   10.7 90   114 86 4.0
C-38 E,G,N A 3768 3793 3702 8.73 5.71 15.9 367: 91 317 227: 2.2
C-39 E,G,N A 3842: 3811 3936 5.17 12.9 9.4 413 439 262 191 3.6
C-41 G,N   -- 3219   <2.8 1.42   -- 92     3.1
C-42 G P   3242     7.67     401      
C-44 E,G G   1289 1288   6.76 3.5   141 141    
C-46 E,G,N N -- 5759 5365 <2.8 2.91 4.6 -- 109 464   3.1




 
Table 2: continued
PRC H I Observations -- $V_{\rm HI}$ -- -- $\int$SdV -- -- $\Delta$V20 -- $\Delta$V50 rms
No. Telescope codes Nan GB Eff Nan GB Eff Nan GB Eff Nan Nan
  Survey Others [km s-1] [Jy km s-1] [km s-1] [km s-1] [mJy]

                         
Possible candidates for polar-ring galaxies - continued            

                         
C-48 G     --     <10.7     --      
C-49 E,N A 4470   4474 2.07   1.1 303   293 262 2.3
C-50 E,G,N N 6559 6773 6560 2.43 1.96 3.9 540: 163 595 517 2.6
C-51 E,G,N G 5497 -- -- 1.40 <4.8 <3.4 184: -- -- 174: 4.1
C-60 E,G,N   -- 6529 -- <2.6 5.42 <4.5 -- 573 --   2.9
C-64 G,N   5696 5716   2.18 4.55   269 342   217 4.5
C-69 G A,E,N,V   2072     16.1     247      

                         
Systems possibly related to polar-ring galaxies            

                         
D-02 E,G,N   6748 6710 6765 1.37 2.84 2.4 243 282 303 212 2.8
D-03 E,G,N   6614 6610 6635 1.55 2.62 3 136 220 135 75 2.6
D-04 G     5162     14.0     442      
  G     5593     1.38:     167:      
D-12 E,N   7778   -- 2.13   <3.7 283   -- 267 2.4
D-14 E,N   5985   5990 13.82   16.2 395   331   6.2/7.9
D-15 E A,E,G,N,W     983     54.4     234    
D-16 E,N   --   -- <4.0   <8.3 --   --   3.3
D-19 N A 7072     1.88     270     252 2.3
D-21* E,N A (471   475 0.59   0.63 48   47 33) 2.7
D-22 E,G,N A 1327 1053 1325 1.58 3.20 2.3 293 141 274 257 2.1
D-23 E,N G,G43,P --   1396 <1.9   0.55     91   2.1
D-24* E       2806     1     390    
D-25 E,G,N A -- 7024 -- <4.0 2.95 <2.9   279 --   3.3
D-28 E,G,N A,V 7272 7197 -- -0.7: 3.78 <5.9 198 616 -- 165 2.2
D-30 G     6055     9.05     284      
D-35 E,G G43,N,V   4752 4750   4.58 3.8   191 223    
D-43 E,G,N N 3451 -- 3452 5.85 <10.0 3.1 573 -- 571 559 2.2
D-44 E A,G,G43,J,N     2189     21.3     450    
D-46 E A,G     3078     2.2     234    

Notes: N/Nan = Nançay, G/GB = Green Bank, and E/Eff = Effelsberg data, for other telescope codes: see Sect. 3.2 and footnote to Table 3; -- means no detection. Upper limits to the integrated line flux $\int$SdV are 3$\sigma$ values for linewidths depending on luminosity, see text. * B-10, B-13 and B-14: have redshifts outside the H I search range; D-21 and D-24: these detections are unrelated to the PRC objects.


3.2 Notes to individual galaxies

Here we give detailed notes on all objects observed at Nançay, as well as on other objects for which the Green Bank and Effelsberg data show discrepant H I velocities, line widths, or integrated line fluxes. We have indicated for each object with which telescopes it has been observed for our PRG H I survey, or for other projects (see also Table 3): A = Arecibo 305-m, AT = Australia Telescope, E = Effelsberg 100-m, G = Green Bank 90-m, G43 = Green Bank 43-m, IAR = I.A.R. 30-m, N=Nançay 94-m equiv., J = Jodrell Bank 76-m, P = Parkes 64-m, R = RATAN 600, V = VLA and W = Westerbork. The listed upper limits to the integrated H I line flux are 3$\sigma$ limits for flat-topped profiles using estimated widths depending on the blue luminosity of the galaxies. The linewidths of detected PRC objects show an increase with luminosity (van Driel et al., in prep.), though with large scatter. We used the average $\Delta V_{20}$ linewidth for a given LB. Consequently, the listed upper limits for the Green Bank and Effelsberg non-detections are different from those quoted in Papers I and II, where a linewidth of 250 kms-1 was assumed for all objects. For the 3 non-detected objects without known blue luminosity (B-20, B-23 and B-24) a linewidth of 250 kms-1 was assumed, being the average of all detected objects in the sample.

Photographs of Schmidt telescope sky survey-quality of all objects can be found in PRC, and explicit reference is made only to images published elsewhere.

The following data on possible companions detectable within the Nançay beam were extracted from the NED and LEDA database, searching in an area of 5$'\times$28'( $\Delta\alpha\times\Delta\delta$), i.e. 1.25 times the 4$'\times$22'Nançay HPBW in R.A. and in Dec, centered on the pointing positions of the telescope (see Table 1). A search for nearby optical companions of many PRGs was made by Brocca et al. (1997).


Kinematically confirmed PRGs


A-01 = A0136-0801. (E,G,N,V) Well-studied object with a polar ring extending to about three times the radius of the equatorial disc; for images, surface photometry and spectra: see Schweizer et al. (1983), Reshetnikov et al. (1994). Listed as one of the disc-dominated PRGs with large polar rings by Reshetnikov & Sotnikova (1997). Mapped in H I with the VLA by Cox et al. (1995) and van Gorkom et al. (1987), who detected an integrated H I line flux of 1.1 and 2.9 Jy kms-1, respectively. All H I emission is found to be associated with the polar ring, whose outer H I contours appear to warp away from the poles. The H I distribution and velocity field are quite regular, indicating an old and possibly stable ring. The central stellar velocity dispersion is 67 kms-1 (Schweizer et al. 1983; Whitmore et al. 1987). No other galaxies were found within the Nançay search area. A-02 = ESO 415-G26. (G,N,V) Its polar ring is less extended than the stellar disc in optical images; it has extensive debris at a position angle intermediate between those of the disc and the ring, as well as shells and loops in the outer regions - see Schweizer et al. (1983), van Gorkom et al. (1987), Whitmore et al. (1987) and Reshetnikov et al. (1994). Listed as one of the bulge-dominated PRGs with short, narrow rings by Reshetnikov & Sotnikova (1997). Mapped with the VLA by van Gorkom et al. (1987), who detected 3.2 109${M}_\odot$ of H I. Both Nançay and Green Bank profiles, centered at 4665  kms-1 and 400 kms-1 wide, could be confused by the very nearby ( $0'\,\hspace{-1.7mm}.\hspace{.0mm}1$ separation) galaxy [RC3] 022508-315509 at 4530 $\pm$ 15  kms-1, within the linewidth of the PRG. No other galaxies were found within the Nançay search area.

A-06 = UGC 9796 = II Zw 73. (E,G,N,V,W) Very faint polar ring, whose H$\alpha$ kinematics show it to be actually a differentially rotating disc, about 25$^\circ$ from perpendicular to the equatorial disc; No nuclear H$\alpha$ emission (Reshetnikov & Combes 1994). Images, surface photometry: see Reshetnikov et al. (1994), Reshetnikov & Combes (1994) and PRC; optical rotation curve: see Makarov et al. (1997). Listed as one of the disc-dominated PRGs with large polar rings by Reshetnikov & Sotnikova (1997). Since the Green Bank and Effelsberg profiles look quite different, the galaxy was also observed at Nançay. VLA imaging observations (Cox et al. 1995; van Gorkom et al. 1987) show that all our single-dish spectra are confused by companion galaxies, however; for example, 7 companions were detected at the VLA within the Green Bank beam area, resulting in a integrated H I line flux 5 times higher than that of the PRG itself. The VLA images show that in the PRG all H I emission is associated with the polar ring, whose outer H I contours appear to warp away from the poles, in the same sense as the optical warp. No sign of interaction was found between the PRG and its close companion, MCG 07-31-049, a 15.7 mag Irregular at $V_{\rm hel}=5470$  kms-1 (63  kms-1 higher than that of the PRG) at $1'\,\hspace{-1.7mm}.\hspace{.0mm}4$ distance. The only other object within the Nançay search area is a 15.7 mag galaxy pair of $0'\,\hspace{-1.7mm}.\hspace{.0mm}5$ diameter with a redshift of 5606 kms-1, at $1'\,\hspace{-1.7mm}.\hspace{.0mm}5$ distance.


 \begin{figure}\addtocounter{figure}{-1} \psfig{figure=ds1681fig1b.ps,width=18cm} \end{figure} Figure 1: b) Nançay 21-cm H I line spectra - continued

B-03 = IC 1689. (A,N,V) An S0-type galaxy with a warped disc and a blue inner polar disc of only 2 kpc radius. Listed as one of the bulge-dominated PRGs with short, narrow rings by Reshetnikov & Sotnikova (1997). Surface photometry and images: see Hagen-Thorn & Reshetnikov (1997), Reshetnikov et al. (1995), van Gorkom et al. (1987) and the PRC. Two-dimensional spectroscopy of the inner parts (Sil'chenko 1998) shows the orthogonality of star and gas rotation and evidence for a central secondary star formation burst. Not detected at Nançay (line flux <2.1 Jy kms-1), nor at the VLA or Arecibo; best upper limit is 0.55 Jy kms-1 (see Table 3), which sets an upper limit of about 5.5 108 ${M}_\odot$ to the H I mass (for H0=75  kms-1Mpc-1) and of 0.085  ${M}_\odot$/ $L_{\odot,B}$ to the ${M}_{\rm HI}$/LB ratio. Four other galaxies were found within the Nançay search area: (1.) IC 1690, a 14.9 mag elliptical at a redshift of 4537 kms-1, at $6'\,\hspace{-1.7mm}.\hspace{.0mm}3$ distance, (2.) NPM1G +32.0060 (Klemola et al. 1987), a 15.9 mag elliptical at a redshift of 5158 kms-1, at $9'\,\hspace{-1.7mm}.\hspace{.0mm}1$ distance, (3.) the galaxy pair NGC 507/508 (= Arp 229), at an average distance of 13'; NGC 507 is a 12.2 mag early-type spiral of type SA(r)00 at a redshift of 4924  kms-1, and NGC 508 is a 14.1 mag probable elliptical at a redshift of 5529 kms-1. They are listed as members of the NGC 507 group of galaxies (Garcia 1993). Though all four have redshifts within the range of the Nançay spectrum (3970-5170  kms-1), only NGC 507 could be a possible source of confusion, but no line emission was detected from this galaxy. Modelling of its kinematics indicates a flattened dark halo surrounding the PRG.

B-17 = UGC 9562. (A,G,N,V,W) Mapped at the VLA by Cox et al. (1995), who found that the H I is more orderly than earlier low-resolution Westerbork observations (Balkowski 1978) suggested. There is a long streamer of gas connecting the ring spatially and in velocity with II Zw 70, a star-forming dwarf galaxy about 4 arcmin away. The streamer of gas and the dwarf II Zw 70 each have about 1/3 of the H I flux from II Zw 71 itself.

B-19 = AM 2020-504. (P) This is the best-studied case to date of a PR around an elliptical: the optical luminosity profile of the central stellar component follows the R1/4 law (Arnaboldi et al. 1993a). The optical and K-band imaging of the polar-ring shows a gentle warp: the PR is probably stable, giving time to stars to form and grow old. This galaxy has a UV spectrum typical of a starburst galaxy (Arnaboldi et al. 1993b). Our Parkes single dish observations show a total integrated flux of 2.4 Jy  kms-1, centered at 5181 kms-1, with a FWHM of 164 kms-1.

B-21 = ESO 603-G21. (E,G,N) This galaxy exhibits a severely warped structure, which appears dark when crossing the stellar central body - photograph: see Schweizer et al. (1983), CCD image: see PRC. Also identified as possible PRG in Buta (1995). The near-infrared imaging in the K-band (Arnaboldi et al. 1995) showed that most of the stellar light comes from a bright nearly-exponential disk in the plane of the warped dusty structure, and the warp is clearly visible in the K-light. The central round body visible in the optical images is quite faint in the near-infrared. Analysis of the K-image showed the presence of a filament perpendicular to the edge-on exponential disk, which is possibly the true polar ring. Our Parkes single dish observations for ESO 603-G21 give a central velocity 3193 kms-1, a FWHM of 217  kms-1 and a total integrated intensity of 14.4 Jy kms-1. The total H I mass associated with this object is 6.2 109 ${M}_\odot$ Since the Green Bank and Effelsberg profiles have a 270 kms-1 central velocity difference, the galaxy was also observed at Nançay, where we found a central velocity (3165 kms-1) and $\Delta$V20 width (286 kms-1) similar to the Green Bank results. No other objects were found within the Nançay search area, but the Green Bank and Effelsberg observations are confused by an object at basically the same redshift as B-21: ESO 603-G20, a 14.7 mag edge-on superthin galaxy, located 5' W of the PRC object, for which a Nançay H I flux of 8.6 Jy kms-1 was measured, centered at 3189 kms-1 with a FWHM of 216  kms-1 (Theureau et al. 1998) - the presence of this object in the beams cannot explain the discrepancy between the Green Bank and Effelsberg profiles, though. No other objects were found within the Nançay search area.

C-24 = UGC 4261. (A,E,G,N) Possibly in the process of forming a ring through accretion (Reshetnikov & Combes 1994). Multicolor surface photometry: Reshetnikov et al. (1998). The H$\alpha$ rotation curve (Reshetnikov & Combes 1994) along the suspected ring (or, probably, ring in formation) is asymmetric. Has an H II-type nuclear spectrum (Reshetnikov & Combes 1994; Keel 1985; Weistrop & Downes 1991). One other galaxy was found within the Nançay search area: KUG 0808+370, a 17 mag spiral of unknown redshift, at $8'\,\hspace{-1.7mm}.\hspace{.0mm}8$ distance.


Good candidates


A1254-1230. (N) Not in PRC, but identified as good PRG candidate by Schechter et al. (1993), who give an optical redshift. Not detected at Nançay (line flux < 1.7 Jy kms-1). No other galaxies were found within the Nançay search area.

ESO 235-58. (P) This galaxy was erroneously classified as a barred spiral galaxy, with a weak broken ring surrounding a bar, but a later analysis of the optical images showed it to be a polar ring (Buta & Crocker 1993): the un-sharp masking revealed a dust lane along the elongated component, previously identified as a bar, showing it to be an edge-on S0. CCD photometry: Buta & Crocker (1993). Single dish H I observations (Mathewson 1993, private communication) done at Parkes indicated a central velocity of 4310 kms-1, a FWHM of 292 kms-1 and a total line flux of 5.8 Jy kms-1.

B-01 = IC51 (E,G,N) The ring has about the same size as the inner component, and the galaxy has an extensive set of distinct outer stellar shells - photos: see Arp (1966) and Hernquist & Quinn (1988); optical and radio imaging: see Mollenhoff et al. (1992); Secondary nucleus - see Forbes et al. (1994). Mapped in H I at the VLA by Schiminovich (see Galletta et al. 1997) who found emission around 1725 kms-1 only; the CO and H I may have different kinematics. Our Parkes H I profile shows a detection centered at 1763 kms-1, with a FWHM of 175 kms-1 and an integrated line flux of 10.9 Jy kms-1. An H2 mass of 7 108 ${M}_\odot$ was derived from CO(1-0) line mapping by Galletta et al. (1997), centered at 1666 kms-1. The claim (in Galletta et al. 1997) that our Nançay H I data show detections at other velocities (in the range of 1310- 1900 kms-1) is in error; the spectrum presented here is fully consistent with the Green Bank and Effelsberg data.

B-08 = AM 0623-371 (N) Has a small luminous component perpendicular to the main body. This object was first observed in the velocity-search mode (range 340- 10007  kms-1) and detected as a weak profile straddling two correlator banks. We therefore reobserved it in the same mode as the other objects with known redshift - the quoted profile parameters (Table 3) are from the latter observations. There are several other objects within the Nançay search area, members of the Abell 3390 cluster at redshifts of about 9500 kms-1, none of which could cause confusion with the H I detection at 2863 kms-1. Note that the reference CSRG 0497 (Buta 1995) refers to the nearby 9745 kms-1 object, not to B-08 (though in the NED and LEDA database B-08 and CSRG 0497 are regarded as one and the same object).

B-09 = UGC 5119. (N) Has a very faint, small component perpendicular to the main body. It was not detected at Nançay (line flux <1.7 Jy kms-1), but detected at Effelsberg with a line flux of 7 Jy kms-1, see Paper II where it is erroneously listed as B-10 in Table 1. The Effelsberg spectrum appears affected by strong radio interference, and the "detection'' could therefore well be spurious. There are no other published H I observations of this object. Long-slit H$\alpha$ spectra (Reshetnikov & Combes 1994) show strong line absorption and no nuclear H$\alpha$ emission. No optical emission lines were found by Osterbrock & Dahari (1983). No other galaxies were found within the Nançay search area.

B-10 = A0950-2234. (E,N) Faint structure perpendicular to the main axis, extending to about twice the radius of the principal disc. Not detected at Nançay (line flux <2.0 Jy kms-1), but the redshift of 14700 kms-1 reported by Sackett & Jarvis (private comm.), and unknown at the time of the Nançay observations, lies well outside the velocity search window. Note that the detected object listed as B-10 in Table 1 of Paper II is in fact B-09. This object is not listed in the NED or LEDA database, nor were any other objects found within the Nançay search area.

B-12 = ESO 503-G17. (G,N) One of the best defined polar ring candidates in Category B; the perpendicular structure extends to about twice the radius of the principal disc. The optical redshift is from Jarvis & Sackett (private communication, see Paper I). No other objects were found within the Nançay search area.

B-13 = Abell 1631-14. (N) Faint, broad ring structure inclined about 30$^\circ$ to the minor axis, extended to about twice the radius of the principal disc. Not detected at Nançay (line flux <2.7 Jy kms-1), but the redshift of 16200 kms-1 reported by Sackett & Jarvis (private comm.), and unknown at the time of the Nançay observations, lies well outside the velocity search window. Three other members of the Abell 1631 cluster were found within the Nançay search area: Nos. 7, 9 and 10 with redshifts of 14909, 14654 and 14345 kms-1 (Dressler & Schectman 1988), respectively. If the PRG is a cluster member its redshift would be well beyond our H I search range of 340 to 10007 kms-1.

B-14 = Abell 1644-105. (N) Ring is too faint to be seen on POSS plates, but CCD imaging shows it to be well-defined and symmetric (PRC). Not detected at Nançay (line flux <2.8 Jy kms-1), but the redshift of 15800  kms-1 reported by Sackett & Jarvis (private comm.), and unknown at the time of the Nançay observations, lies well outside the velocity search window. All 5 objects found within the Nançay search area are 15 or 16$^{\rm th}$ mag E or S0 galaxies and members of cluster Abell 1644 (Abell et al. 1989) at a mean redshift of 14213 kms-1 (Zabludoff et al. 1993).

B-16 = NGC 5122. (N,V) Listed as one of the disc-dominated PRGs with large polar rings by Reshetnikov & Sotnikova (1997). Its faint ring is smooth and warped, and very nearly perpendicular to the disc, and both are seen nearly edge-on; CCD image by J. Gallagher & L. Matthews: in Cox et al. (1995). Stellar absorption lines only were found by Rodgers et al. (1978). The galaxy was observed at a higher, incorrect redshift, at both Green Bank and Nançay. The galaxy was detected in Nançay at the correct redshift by Theureau et al. (1998), see Table 3; no confusing objects were found within the Nançay search area. Mapped in H I at the VLA (Cox et al. 1995), who found that the H I is associated with the ring, not with the host galaxy. The ring is asymmetric and extends towards a companion galaxy, MCG-02-34-045, a 15.5 mag Sc/d object at $V_{\rm hel}=2929$  kms-1 (74 kms-1 higher than that of the PRG) at $11'\,\hspace{-1.7mm}.\hspace{.0mm}6$ distance. The polar ring gas is not warped, and no gaseous bridge is visible between the two companion galaxies.

B-20 = A 2135-2132. (N) Not detected at Nançay (line flux <2.5 Jy kms-1). This object is not listed in the NED database, nor were any other objects found within the Nançay search area.


 \begin{figure}\addtocounter{figure}{-1} \psfig{figure=ds1681fig1c.ps,width=18cm} \end{figure} Figure 1: c) Nançay 21-cm H I line spectra - continued

B-23 = A 2330-3751. (G,N) Faint structure perpendicular to the major axis, a bit smaller than the major axis diameter of the principal disc. Spectra were obtained at the Siding Spring Observatory 2.3 m telescope and the double beam spectrograph in August 1995 to get the optical redshift along the PR along PA = $156^\circ$. The wavelength range in the blue arm was from 3600 to 5600 Å, and from 6400 to 7005 in the red. No features were indentified upon the continuum emission. Not detected at Nançay or Green Bank (line flux <2.2 Jy kms-1). Only referred to in the PRC and Paper I. The centres of 2 galaxy concentrations lie within the Nançay search area: B-23 is located $5'\,\hspace{-1.7mm}.\hspace{.0mm}7$ from the centre of cluster AM 2330-375 (Arp & Madore 1987), and $8'\,\hspace{-1.7mm}.\hspace{.0mm}5$ from the centre of cluster Abell 4015, both of unknown redshift.

B-24 = A 2333-1637. (N) Asymmetric polar ring, about 45$^\circ$ from perpendicular - transitory configuration? Not detected at Nançay (line flux <2.5 Jy kms-1). This object is not listed in the NED and LEDA database, nor were any possible companions found within the Nançay search area.

B-27 = ESO 293-IG17. (G) Only a slight extension is seen along the minor axis, appears to be surrounded by shell-like nebulosity. After the completion of our H I survey an optical redshift of about 15300 kms-1 was published (Loveday et al. 1996), which places the object well outside the 1000-8000  kms-1 velocity search range used at Green Bank.


Possible PRG candidates


C-06 = NGC 0304. (A,N) Shows faint filaments along the minor axis; it is not clear from surface photometry whether it is an elliptical or a disc system (PRC). Classified by Keel (1985) as an edge-on spiral, based on CCD images. Not detected at Nançay (line flux <2.9 Jy  kms-1), nor at Arecibo (see Table 3), giving a best upper limit to the integrated H I line flux of 1.0 Jy kms-1. No other objects were found within the Nançay search area. C-09 = NGC 0442. (E,G,N) Has a dust lane perpendicular to the major axis, and two short spikes on either side of the galaxy; surface photometry: see PRC. Not detected at Nançay or Effelsberg, but detected at Green Bank. The only other object found within the Nançay search area is IRAS F01119-0128, of unknown redshift, with a flux density of 3.6 Jy at 100 $\mu$m wavelength, at a distance of $10'\,\hspace{-1.7mm}.\hspace{.0mm}6$.

C-12 = UGC 1198 = VII Zw 3 (E,G,N) Small galaxy, crossed by a slight enhancement of light along its minor axis; surface photometry: see PRC. No other galaxies were found within the Nançay search area.

C-14 = NGC 979 (G) No optical redshift has been published for this object. Our Green Bank H I profile of this galaxy is very broad ($\Delta$V20 = 678 kms-1) and centered at 4775 kms-1. This may be due to confusion with ESO 426-22, a 14.8 mag SBc spiral at 9' distance with an optical redshift of 5127 $\pm$ 60 kms-1; no H I spectrum has been published of this galaxy.

C-18 = ESO 358-G20. (G,N) Shows a faint ringlike structure to the north, as well as scattered debris to the southeast and a bright "crescent moon'' feature just south of the nucleus. The Green Bank H I profile is considerably wider than the Nançay profile (167 and 114 kms-1, respectively) - due to interference? Our observations, plus 30 minutes more, were used by Matthews et al. (1998). Within the Nançay search area only two probable ellipticals were found of about 19 mag, without known redshift, at an average distance of $12'\,\hspace{-1.7mm}.\hspace{.0mm}5$. C-25 = UGC 4323. (E,G,N) Maybe in the process of forming a ring through accretion (Reshetnikov & Combes 1994), shows a faint jetlike extension to northeast and an inner dust lane near the minor axis. Optical study by Reshetnikov et al. (1995), optical spectrum: see Moody & Kirshner (1988). It's optical redshift is 3972 $\pm$ 55  kms-1. Asymmetric H$\alpha$ rotation curve (Reshetnikov & Combes 1994). Has a LINER-type nuclear spectrum (Reshetnikov & Combes 1994). It was not detected at Nançay (line flux <2.9 Jy kms-1), while the Green Bank and Effelsberg profiles do not even show an overlap in velocity (the measured mean velocities and $\Delta$V20 widths are 3686, 397  kms-1 and 4037, 250 kms-1, respectively), and the Effelsberg integrated line flux is 4 times smaller than that measured at Green Bank. The complete discrepancy between the two H I spectra, as well as between the Green Bank and optical redshifts appears to be due to interference at Green Bank rather than to confusion with other galaxies in the beams.

C-26 = UGC 4332. (A,E,G,N) Optical and near-infrared imaging: Gavazzi et al. (1994, 1996a); Hubble Space Telescope imaging of central regions: Malkan et al. (1998). A Seyfert-type nuclear spectrum was reported in Reshetnikov & Combes (1994), though the work by Braatz et al. (1996) shows no optical emission lines. Asymmetric H$\alpha$ rotation curve (Reshetnikov & Combes 1994), probably due to extended dust features. No H2O megamaser activity was detected (Braatz et al. 1997). Not detected at Nançay (line flux <2.3 Jy kms-1), while at Effelsberg a velocity of 5412 kms-1 was measured, 350 kms-1 lower than at Green Bank, and a two times larger FWHM (620 kms-1). Three Arecibo detections (see Table 3 ) indicate a mean systemic velocity of 5486 kms-1, a FWHM of 450  kms-1 (consistent with the optical velocity of 5505 $\pm$ 94 kms-1) and a line flux of 2.5 Jy kms-1. There appear to be no objects that could cause confusion within the Arecibo beam. One other galaxy was found within the Nançay search area: 16.2 mag object Cf11 (Corbelli et al. 1991), of unknown redshift. Also within the Nançay search area, at $6'\,\hspace{-1.7mm}.\hspace{.0mm}3$ distance from C-26, lies the centre of group LGG 158 (Garcia 1993) in the Cancer II group, of unknown redshift. Ten galaxies are listed within the Green Bank HPBW in the NED database - 8 with known redshifts, of which 2 with a redshift within 500 kms-1 of the PRC object: NGC 2562 (4999 kms-1) and CGCG 119-061 (5180 kms-1); neither was detected in H I, with published upper limits of 0.53 and 0.8 Jy kms-1, respectively (see Huchtmeier & Richter 1989).

C-28 = NGC 2748. (E,G,J,N,W) Exhibits a faint structure perpendicular to the stellar disc, and appears to be a spiral galaxy surrounded by a polar ring. It may be in the process of forming a ring through accretion (Reshetnikov & Combes 1994). Flat H$\alpha$ major axis rotation curve, H II-type nuclear spectrum (Reshetnikov & Combes 1994; Ho et al. 1997). Its optical kinematics were studied by Hagen-Thorn et al. (1996) and Courteau (1997). Deep r-band CCD surface photometry: see Courteau (1996) and Héraudeau & Simien (1996). Radial luminosity profile fit shows no evidence for a bulge (Baggett et al. 1998). The only possible other galaxy within the Nançay search area might the 16.9 mag object IRAS F09075+7631, of unknown redshift, at a distance of 10'. The FWHM of the Nançay profile (313 kms-1) is consistent with the 5 other literature values (see Table 3), and much broader than the 140 kms-1 measured at Effelsberg.

C-30 = UGC 5101. (E,N) Shows an inner disc-like extension along the minor axis. Multicolor surface photometry: Reshetnikov et al. (1998) Ultraluminous IRAS galaxy (e.g., Sanders et al. 1988), with LINER/Seyfert spectrum (Kim et al. 1995; Veilleux et al. 1995; Goncalves et al. 1999) and OH line megamaser (Henkel 1990; Martin et al. 1989). Long-slit H$\alpha$ spectrum: see Reshetnikov & Combes (1994). The Nançay profile shows a 152 kms-1 wide absorption profile centered on 12053 kms-1, within the $\pm$214 kms-1 error on the 134 kms-1 higher optical redshift. The profile could be an off-band detection, as the continuum flux density of the PRC object at 20 cm, 158 mJy (White & Becker 1992), seems too feeble for pronounced self-absorption. The Effelsberg observations did not cover this high velocity range. Optical imaging: see Smith et al. (1996), near-infrared imaging: see Majewski (1993), radio continuum imaging: see Crawford et al. (1996). No other galaxies were found within the Nançay search area.

C-32 = IC 575. (E,N) Has an underlying elliptical-like luminosity profile, with strong dust lanes along the major axis and a ringlike disc. Photo: see Arp (1966), surface photometry: PRC, V-band CCD image: see Mollenhoff et al. (1992), whose VLA continuum images show a compact radio core coinciding with the optical intensity peak. Detected by us at Effelsberg, but not at Nançay; no other published H I detection exists. Three other objects were found within the Nançay search area: (1.) VV 111a/b, a galaxy pair of unknown brightness and redshift, at $1'\,\hspace{-1.7mm}.\hspace{.0mm}4$ distance (2.) MCG -01-25-057, a 17 mag object of unknown redshift, at $2'\,\hspace{-1.7mm}.\hspace{.0mm}3$ distance, and (3.) IC 0574, a 15 mag early-type disc galaxy (SA0-:), at $6'\,\hspace{-1.7mm}.\hspace{.0mm}2$ distance.

C-33 = ESO 500-G41. (E,N) Shows spiral structure, unlike most other candidates, and was classified as (R)SA(r)ab in Buta (1995), with an inner and an outer ring of $0'\,\hspace{-1.7mm}.\hspace{.0mm}6$ and $1'\,\hspace{-1.7mm}.\hspace{.0mm}3$ diameter, respectively. The absorption line seen in the Nançay spectrum must be due to the Off-position detection of another object, centered at a velocity of 3755 kms-1 with profile widths $\Delta$V50 = 61 and $\Delta$V20 = 233 kms-1, as the Effelsberg profile shows only H I emission. The Nançay emission line detection of C-33 may in principle be confused by this Off-band detection, but the Nançay and Effelsberg central emission line velocities correspond to within 10 kms-1. No other galaxies were found within the Nançay search area.

C-34 = NGC 3384. (A,G,J,N) Classified as SB01 in the RSA, it shows a disc-like component in the inner regions along the minor axis (Davoust et al. 1984). It has a disc-to-bulge luminosity ratio of 0.9, a disc scalelength of 2.7 kpc (Fisher et al. 1996; Baggett et al. 1998) and a central stellar velocity dispersion of 150 kms-1 (Fisher et al. 1996; Prugniel & Simien 1996). Near-infrared photometry: see Jungwiert et al. (1997). Optical spectra: stellar line strengths and their gradients were measured by Fisher et al. (1996); no emission lines are visible in the spectra of Ho et al. (1995, 1997). No stellar counter-rotation was found by Kuijken et al. (1996), only a suggestion of independent kinematical components like nuclear discs and bars. Member of the LGG 217, or Messier 96 (Leo I), group (Garcia 1993). Part of a second, stronger, line profile is seen at the high end of the Nançay band (at 1150-1400 kms-1), which is undoubtedly due to NGC 3389, a 12.4 mag Sc spiral at the edge of the Nançay beam ( $2'\,\hspace{-1.7mm}.\hspace{.0mm}8$ E and $5'\,\hspace{-1.7mm}.\hspace{.0mm}7$ S of C-34) at an H I redshift of 1298  kms-1 with a FWHM of about 245 kms-1 (Helou et al. 1981; Staveley-Smith & Davies 1988) and a line flux of about 26 Jy kms-1. The PRC object was detected at Nançay (line flux 1.5 Jy kms-1), but not at Arecibo - the best published Arecibo upper limit is 0.62 Jy kms-1 (see Table 3). The well-established optical redshift of the PRC object, 735 $\pm$ 36 kms-1, is 170 kms-1 lower than the Nançay value, 903 kms-1, and the H I profile is quite narrow, $\Delta$ V20 =93  kms-1. Given this descrepancy, the non-detection at Arecibo and the lack of confusing galaxies in the neighbourhood, we may have detected a tail or bridge of H I far from the galaxy's center due to interaction with its nearby companion NGC 3379, a 10.2 mag elliptical at a redshift of 888 kms-1. C-35 = NGC 3414. (A,E,G,N) Has unusual isophotes, considered to be a box or X-galaxy by Whitmore & Bell (1988), and faint extensions perpendicular to the major axis suggest the possibility of a ring (PRC). Has an optical LINER emission line spectrum (Ho et al. 1995, 1997) The central stellar velocity dispersion is 253 kms-1 (see Prugniel & Simien 1996, and references therein), and the maximum stellar rotation velocity about 55 kms-1 (Lake & Dressler 1986). Three other objects were found within the Nançay search area: (1.) NPM1G +28.0180 (Klemola et al. 1987), a 16.1 mag object at a redshift of 1142 kms-1, at 2' distance, (3.) NGC 3418, a 14.1 mag early-type (SAB(s)0/a:) spiral with an optical redshift of 1251 $\pm$ 52 kms-1, at $8'\,\hspace{-1.7mm}.\hspace{.0mm}5$ distance, and (3.) UGC 5958, a 15.3 mag Sbc spiral at $7'\,\hspace{-1.7mm}.\hspace{.0mm}6$ distance, detected in H I at Arecibo with a line flux of about 2.6 Jy kms-1 at a redshift of 1182 kms-1 with a FWHM of 185 kms-1 (Bicay & Giovanelli 1986; Giovanelli et al. 1997; Schneider et al. 1986). The PRC object has a well-established optical redshift of 1445 $\pm$ 63 kms-1. Our Nançay and Effelsberg spectra do not even show an overlap in velocity (the measured mean velocities and $\Delta$V20 widths are 1173, 325: kms-1 and 1526, 322 kms-1, respectively), and the Effelsberg integrated line flux is 2.5 times smaller than the Nançay value. The two published Arecibo profiles of the PRC object, which should be free of confusion with NGC 3418 and UGC 5958, do not have any overlap in velocity either, as their mean velocities and FWHMs are 1414, 330  kms-1 (Bieging & Biermann 1977) and 1592, 256  kms-1 (DuPrie & Schneider 1996), respectively. DuPrie & Schneider actually mapped the NGC 3414 group at Arecibo and found no evidence of extended H I features within the group.

C-37 = UGC 6182. (E,G,N) One other galaxy was found near the edge of the Nançay search area: UGC 6182, a 14.7 mag spiral of unknown redshift and $1'\,\hspace{-1.7mm}.\hspace{.0mm}3$ diameter, at $12'\,\hspace{-1.7mm}.\hspace{.0mm}5$ distance.

C-38 = NGC 3934. (A,E,G,N) Already recognized as a PRG by Schweizer et al. (1983); CCD images (PRC) show a structure resembling two crossed discs in the inner regions, as well as extensive shells in the outer region. The galaxy was observed at Nançay as the Effelsberg profile is much stronger (15.9 vs. 5.7 Jy kms-1) and wider ($\Delta$V20 317 vs. 91 kms-1) than measured at Green Bank; also, the Green Bank spectrum shows only one peak, while the Effelsberg data show two. The Nançay spectrum shows 3 peaks, centered at about 3610, 3775 and 3805 kms-1; at Green Bank only the middle peak was detected, while at Effelsberg both the middle and the lowest-velocity peak were seen. The Green Bank observations may well be unreliable, however, as they were plagued by solar interference, affecting the baseline. Published Arecibo detections (see Table 3) indicate detections of the middle peak only (V=3740  kms-1 and $\Delta V_{20}=290$  kms-1, I=4.4 Jy  kms-1). The peaks at 3610 and 3775 kms-1 may well be due to confusion by 14.3 mag NGC 3933, located $2'\,\hspace{-1.7mm}.\hspace{.0mm}7$ W and $2'\,\hspace{-1.7mm}.\hspace{.0mm}6$ S of the PRC object, on the edge of the Nançay beam but well inside the other beams. H I spectra of NGC 3933 (see Huchtmeier & Richter 1989) show a systemic velocity of about 3731 kms-1 and a $\Delta$V20 width of 355  kms-1, measured with the $1'\,\hspace{-1.7mm}.\hspace{.0mm}9$ radius Arecibo beam, and thus in principle free of confusion by C-38 at a distance of $3'\,\hspace{-1.7mm}.\hspace{.0mm}7$, unless it has an H I size much larger than its optical dimensions, about 1' diameter. The question remains why the narrow peak at 3805 kms-1 was observed only at Nançay; no other galaxies were found within the Nançay search area, and only one catalogued object of unknown redshift (16 mag UGC 6835) was found at the edge of the Effelsberg beam, $6'\,\hspace{-1.7mm}.\hspace{.0mm}2$ from C-38.

C-39 = NGC 4174. (A,E,G,N) Very faint polar ring-like feature, CCD image: see PRC. All our H I survey profiles are likely to be confused, as it is in a compact group of galaxies, HCG 61 (Hickson 1982). The Green Bank and Effelsberg line fluxes are comparable (average 11 Jy  kms-1) and 2.3 times higher than measured at Nançay, while the Effelsberg profile width (262  kms-1) is 1.8 times narrower than the others. CCD imaging (broad-band and H$\alpha$: see Hickson et al. (1988), Mendes de Oliveira & Hickson (1994), Vilchez & Iglesias-Paramo (1998a, 1998b). The optical redshift of the PRC object is 4010 $\pm$ 73 kms-1. Several other objects were found within the Nançay search area: (1.) NGC 4175, a 14.2 mag Sbc spiral with an optical redshift of 4001 $\pm$ 43 kms-1, at $1'\,\hspace{-1.7mm}.\hspace{.0mm}5$ distance, (2.) NGC 4169, a 13.1 mag early-type (S0a) galaxy with an optical redshift of 3783 $\pm$ 28 kms-1, at $2'\,\hspace{-1.7mm}.\hspace{.0mm}4$ distance, (3.) NGC 4170, a 13.6 mag Sdm spiral at the much lower redshift of (4.) 1127 kms-1, at $3'\,\hspace{-1.7mm}.\hspace{.0mm}4$ distance, and (5.) three 17-18 mag galaxies, Nos. 101-103 from Kent et al. (1993), of unknown redshift, at about $5'\,\hspace{-1.7mm}.\hspace{.0mm}5$ distance. Even the published Arecibo spectrum of Sulentic & Arp (1983) is bound to be confused - note its width of 547  kms-1 (Table 3). C-41 = IC 3370. (G,N) Though generally considered a box-shaped elliptical, with a prominent dust lane in its inner regions, there is evidence for cylindrical rotation and X-shaped isophotes (Jarvis 1987; Goudfrooij 1994a, 1994b; Keel & Wu 1995; Penereiro et al. 1994). Two possible nuclei in addition to the primary one were identified by Forbes et al. (1994). The central stellar velocity dispersion is 202 kms-1 (see Prugniel & Simien 1996), and the maximum stellar rotation velocity about 95 kms-1 (Carollo et al. 1993; Jarvis 1987). Detected at Green Bank, but not at Nançay (with a higher rms noise). No other object was found within the Nançay search area.

C-44 = NGC 5103 (E,G) This object has an optical redshift of 1283 $\pm$ 50 kms-1. Our Effelsberg and Green Bank profiles show the same central velocity (1289  kms-1) and $\Delta$V20 width (141 kms-1), though the Effelsberg flux (6.8 Jy kms-1) is almost two times larger. Of the 3 other published Green Bank profiles (see Table 3), one has a mean velocity of 1289 kms-1, while the two others are centered on 1225 kms-1, with a line flux of 10.5 Jy kms-1, 3 times that of the other spectrum.

C-46 = ESO 576-G69. (E,G,N) Galaxy wrapped by a series of optical arcs, and with a long tidal tail. CCD imaging: see Giraud (1986). Also identified as possible PRG in Buta (1995). Not detected at Nançay (line flux <2.3 Jy kms-1), while the Effelsberg profile is 4.5 times broader (464 kms-1) than the Green Bank profile, and has a 400 kms-1 lower central velocity. The strong and broad Nançay detection by Boissé et al. (1988) is incompatible with any of our survey data (see Table 3), and may be spurious. Two other galaxies were found within the Nançay search area: (1.) ESO 576-G070, a 14.6 mag lenticular of unknown redshift and a diameter of $1'\,\hspace{-1.7mm}.\hspace{.0mm}3$, at 5' distance, and (2.) IRAS F13274-2051, a 15.7 mag object of unknown redshift, at $11'\,\hspace{-1.7mm}.\hspace{.0mm}6$ distance.

C-49 = NGC 6028. (A,E,N) The nearest and brightest outer ringed, Hoag-type galaxy. Images and surface photometry, as well as a discussion of the nature of the object: see Schweizer (1987), Wakamatsu (1990) and Gavazzi et al. (1995). No other galaxies were found within the Nançay search area.


  \begin{figure}\psfig{figure=ds1681fig2.ps,width=18cm}\end{figure} Figure 2: A comparison of integrated H I line fluxes, on a logarithmic scale, from the present survey at Nançay, Green Bank and Effelsberg, as well as from other published sources for the Arecibo observations. To guide the eye, a diagonal solid line with a slope of 1 was plotted in each pannel; these lines are not fits to the data. a) Nançay vs. Green Bank, b) Nançay vs. Effelsberg, c) Nançay vs. Arecibo (literature values), and d) Green Bank vs. Effelsberg

C-50 = UGC 10205. (E,G,N) Looks like a normal SO/a-Sa type galaxy in many respects, but its edge-on absorption "disc'' (Gavazzi & Randone 1994) shows evidence for a brightness bump in the light profile and a warp (PRC), and deep exposures indicate diffuse debris and shell structure in the outer regions (Rubin 1987, PRC). Long-slit H$\alpha$ spectra show 3 gas kinematic components structures along the major axis, one of which is in counterrotation (Rubin et al. 1985; Vega et al. 1997). Low-resolution near-infrared mapping: see Giovanardi & Hunt (1996). Its main peculiarities were modeled by Reshetnikov & Evstigneeva (1999) as the early stage in the capture and tidal disruption of a small type E/S0 companion by the massive central galaxy. Compared to the Nançay and Effelsberg results, the Green Bank central velocity is 213 kms-1 higher and its 163 kms-1 FWHM is much narrower than the 560 kms-1 measured elsewehere, though the line fluxes are similar. The only possible companion, at the edge of the Nançay search area ( $12'\,\hspace{-1.7mm}.\hspace{.0mm}7$ distance), might be IRAS F16036+3019, of unknown redshift.

C-51 = NGC 6285+6286. (E,G,N) Clear tidal interaction between this close pair ( $1'\,\hspace{-1.7mm}.\hspace{.0mm}5$ separation), and both have debris highly inclined to their central planes. More southern NGC 6286 is the more obvious PRG candidate (according to PRC), while Reshetnikov & Combes (1994) and Reshetnikov et al. (1996) interpret it as a spiral (as opposed to the regular, S0-type, central PRG discs) with a ring of a size comparable to that of the galaxy in an early stage of formation, rotating in an orthogonal plane, accompanied by accretion onto NGC 6285. Deep CCD images show filaments between the systems (see PRC). NGC 6285 H$\alpha$ velocity field and surface photometry: see Reshetnikov et al. (1993b, 1995, 1996). Near-infrared imaging shows the mildly disturbed morphology of NGC 6286, whose major axis H$\alpha$ rotation curve looks regular (Smith et al. 1996). Near-infrared spectra: Smith et al. (1996), Goldader et al. 1997a); resulting starburst model: see Goldader et al. (1997b). Optical spectra show that NGC 6285 has an H II-type spectrum and a complex H$\alpha$ velocity field, while NGC 6286 is a LINER (Carrasco et al. 1997; Veilleux et al. 1995; Kim et al. 1995). One other galaxy was found in the Nançay search area: UGC 10646, a 14.8 mag elliptical of unknown redshift and $1'\,\hspace{-1.7mm}.\hspace{.0mm}3$ diameter, at $12'\,\hspace{-1.7mm}.\hspace{.0mm}2$ distance. C-60 = ESO 464-G31. (E,G,N) Disturbed system, appears to consist of two nearly perpendicular edge-on components, of which one is associated with faint, extended debris. Its optical spectrum shows emission lines, but could not be classified as either Seyfert or LINER by Maia et al. (1996). Divided into two objects of magnitudes of 15.02 and 15.64 by the automated surface photometry of the ESO-LV catalog (Lauberts & Valentijn 1989). Listed as galaxy pair AM 2115-273 in Arp & Madore (1987). No other galaxy was found in the Nançay search area.

C-64 = ESO 343-IG13. (G,N) CCD imaging (No. 57 in van den Broek et al. 1991) show it to be a close, interacting IRAS galaxy pair. Both members have an H II-type spectrum (van den Broek et al. 1991; Kim et al. 1995; Veilleux et al. 1995; Sekiguchi & Wolstencroft 1993). No OH megamaser emission was found by Staveley-Smith et al. (1992). VLA 6 and 20 cm continuum imaging: see van Driel et al. (1991). One other galaxy was found in the Nançay search area, of unknown redshift: ESO 343-G012, a 16.4 mag spiral of $1'\,\hspace{-1.7mm}.\hspace{.0mm}5$ diameter, at $8'\,\hspace{-1.7mm}.\hspace{.0mm}1$ distance.


Systems possibly related to PRGs


D-02 = NGC 235. (E,G,N) This galaxy is member of an optical pair (CCD image: see Keel 1996) and is sometimes listed as having triple/multiple components. Optical debris connects it to its partner, NGC 232, with which the IRAS detection is associated. NGC 235a was classified as (R')SAB(s)a in Buta (1995), with an outer ring of $0'\,\hspace{-1.7mm}.\hspace{.0mm}56$ diameter. Hubble Space Telescope imaging of the inner regions: Malkan et al. (1998). Classified as a Seyfert by Maia et al. (1987); no optical emission lines were found by Braatz et al. (1997). No H2O megamaser activity was detected (Braatz et al. 1996). One other galaxy was found in the Nançay search area: NGC 232, a 14.4 mag SB(r)a? pec type spiral at only 2' distance with a mean optical redshift (LEDA) of 6733 $\pm$ 53 kms-1, 69 kms-1 higher than the optical redshift of the PRC object (6664 $\pm$ 48). The only published H I observation of NGC 232 was obtained with Nançay: at $1'\,\hspace{-1.7mm}.\hspace{.0mm}5$ E and $2'\,\hspace{-1.7mm}.\hspace{.0mm}5$ S of NGC 235, i.e. well within the Nançay HPBW, Martin et al. (1991) detected H I with a line flux of 1.66 Jy kms-1, at $V_{\rm hel}$ = 6675 kms-1 and with $\Delta$V20 = 411 kms-1.

D-03 = ESO 474-IG28. (E,G,N) Photograph: see Johansson (1988). Optical spectroscopy (Johansson 1988) shows an H II-type starburst spectrum, and Coziol et al. (1994) identified it as an UV-bright galaxy. One other object was found at the edge of the Nançay search area: MCG +04-03-007, a galaxy pair at $13'\,\hspace{-1.7mm}.\hspace{.0mm}9$ distance, at a redshift of 16,000 kms-1, far outside our velocity range.


  \begin{figure}\psfig{figure=ds1681fig3.ps,width=18cm}\end{figure} Figure 3: A comparison of H I line widths W20 from the present survey at Nançay, Green Bank and Effelsberg, as well as from other published sources for the Arecibo observations. To guide the eye, a diagonal solid line with a slope of 1 was plotted in each pannel; these lines are not fits to the data. a) Nançay vs. Green Bank, b) Nançay vs. Effelsberg, c) Nançay vs. Arecibo (literature values), and d) Green Bank vs. Effelsberg

D-04 = ESO 296-G11 (G) Photometric and spectroscopic observations (Aguero et al. 1999) of this system, a.k.a. the Boomerang, show that it consists of two advanced late-type galaxies with similar general properties, which form a triple system together with a small nearby galaxy. Optical redshifts are 5267 $\pm$ 53 (NW object) and 5052 $\pm$ 35 kms-1 (SE object), respectively. The integrated B magnitude of the pair is listed as 14.41, and that of the SE object as 17. Of the two Green Bank detections, the weaker one, centered at 5593 kms-1, is marginal, and the stronger is centered at 5192 kms-1. No catalogued confusing objects were found within the Green Bank beam.

D-12 = UGC 4892. (E,N) Possibly in the process of forming a ring through accretion (Reshetnikov & Combes 1994). Has a Seyfert/LINER-type nuclear spectrum, the suspected ring shows a linear H$\alpha$ rotation curve (Reshetnikov & Combes 1994). Three other galaxies were found in the Nançay search area, of which the first pair might be a source of H I confusion: (1.) MCG +08-17-066, a 17 mag $0'\,\hspace{-1.7mm}.\hspace{.0mm}3$ diameter superimposed galaxy pair at $6'\,\hspace{-1.7mm}.\hspace{.0mm}9$ distance, at $V_{\rm opt}$=7806 $\pm$ 32 kms-1 (Fisher et al. 1995), only 28 kms-1 higher than the Nançay profile central velocity, and (2.) MCG +08-17-067, a 16.9 mag $0'\,\hspace{-1.7mm}.\hspace{.0mm}4$ diameter object at $7'\,\hspace{-1.7mm}.\hspace{.0mm}7$ distance of unknown redshift.

D-14 = UGC 5485. (E,N) May be similar to an X- or box-shaped galaxy (PRC). Two other galaxies were found in the Nançay search area: MCG +11-13-004 and MCG +11-13-005. Both are 18$^{\rm th}$ mag objects of $0'\,\hspace{-1.7mm}.\hspace{.0mm}2$ average diameter without known redshifts, not likely to confuse our H I emission line search out to a redshift of 10000 kms-1.

D-16 = NGC 3406. (E,N) Not detected at Nançay and Effelsberg (line flux <2.4 Jy kms-1). Pair of early-type galaxies, separation 20'', optical radial velocities are 7473 and 7138 kms-1, respectively (Davoust & Considère 1995). The central stellar velocity dispersion is 321  kms-1 (White et al. 1983). Not detected in radio continuum (Cordey 1986). Listed as pair in the NED database: a 14.1 mag E-type of $1'\,\hspace{-1.7mm}.\hspace{.0mm}1$ diameter at redshift 7473 $\pm$ 10  kms-1, and a 14.9 mag S0 of $0'\,\hspace{-1.7mm}.\hspace{.0mm}6$ diameter at 7138 $\pm$ 50  kms-1. One other galaxy was found in the Nançay search area: NGC 3410, at $1'\,\hspace{-1.7mm}.\hspace{.0mm}9$distance, a 15.1 mag probable spiral with two highly discrepant published optical redshifts, 7105 (White et al. 1983) and 8292 kms-1 (Huchra et al. 1983).

D-19 = NGC 3808b = UGC 6643. (A,G,N) Northern member of a close interacting pair with luminous bridge and short tails, see the CCD images by Gavazzi & Randone (1994), Laurikainen et al. (1998) and Reshetnikov et al. (1996); H$\alpha$ imaging by Gavazzi et al. (1998); near-infrared photometry by Gavazzi et al (1996b) and Grauer et al. (1998). Considered (Reshetnikov & Combes 1994; Reshetnikov et al. 1996) a galaxy in the process of forming a ring rotating around the major axis of the galaxy through accretion, with a size comparable to that of the galaxy. Very peculiar H$\alpha$ kinematics, with a noticeable offset between the photometric and kinematic centres; the ring (in formation) has a nearly straight H$\alpha$ rotation curve (Reshetnikov & Combes 1994; Reshetnikov et al. 1996). Has a nuclear spectrum on the boundary of AGN and H II-type spectra (Reshetnikov & Combes 1994). Listed as pair, with a $1'\,\hspace{-1.7mm}.\hspace{.0mm}1$ separation: NGC 3808a, a 14.1 mag SAB(rs)c:pec object of $1'\,\hspace{-1.7mm}.\hspace{.0mm}7$ diameter at a mean optical redshift of 7050 $\pm$ 38 kms-1 (LEDA), and NGC 3808b (the PRC object), a 15 mag I0? pec object of $0'\,\hspace{-1.7mm}.\hspace{.0mm}5$ diameter, at 7189 $\pm$ 55  kms-1 (LEDA). No other objects were found in the Nançay search area. D-21 = UGC 7636. (A,E,N,W) V-shaped low-surface brightness galaxy located $5'\,\hspace{-1.7mm}.\hspace{.0mm}6$ to the SE of the giant Virgo Cluster elliptical NGC 4472, with which it is in tidal interaction; see the review paper on dwarf ellipticals by Ferguson & Binggeli (1994). CCD photometry: see McNamara et al. (1994) and Patterson & Thuan (1996). The Nançay and Effelsberg detection are associated with an H I cloud unrelated to the PRC object: an Arecibo observation (Kumar & Thonnard 1983) with a $3'\,\hspace{-1.7mm}.\hspace{.0mm}8$ round beam pointed towards the NW of D-21 showed a narrow emission feature, like our data. An H I profile (Patterson & Thuan 1992) taken with the large beam of the Green Bank 43-m. telescope shows an additional, underlying broad component. Subsequent WSRT H I line imaging has shown the existence of an H I cloud halfway between both galaxies (Henning et al. 1993; Sancisi et al. 1987). The mean optical redshifts of the bright elliptical and D-21 listed in the LEDA database are, respectively, 982 $\pm$ 49 and 276 $\pm$ 60 kms-1 (see Binggeli et al. 1993). The redshift of the H I cloud is 466 kms-1, its centre position is located $2'\,\hspace{-1.7mm}.\hspace{.0mm}2$ to the SW of the centre of D-21 (i.e., well within the Nançay HPBW) and its line flux is 0.49 Jy  kms-1. WSRT and Arecibo observations (see Sancisi et al. 1987) place an upper limit of 2.25 Jy kms-1 for the integrated H I line flux of D-21, which we have assumed to be at the distance of the Virgo Cluster, 13.5 Mpc. Optical surface photometry: see Binggeli & Cameron (1993) and Gallagher & Hunter (1989), near-infrared surface photometry: see James (1991), where the object is referred to as VCC 1249. No other galaxy was found within the Nançay search area and velocity range.



 
Table 3: Other published H I data for the combined polar ring galaxy H I sample
PRC Tel. $V_{\rm HI}$ $\int$SdV $\Delta$V20 $\Delta$V50 Ref. PRC Tel. $V_{\rm HI}$ $\int$SdV $\Delta$V20 $\Delta$V50 Ref.
No. Code [km s-1] [Jy km s-1] [km s-1] [km s-1]   No Code [km s-1] [Jy km s-1] [km s-1] [km s-1]  

                         
A-01 V 5528 1.1 374 411 vG87 A-03 G 930 15.3     K77
  V   2.9 385   C95   W 870 30.9   282 S80
A-02 V 4604 3.7   328 vG87 A-05 V 2910 16.0 243 231 vG87
A-03 N 868 28.5 345 260 B72   AT 2905 23.1 240 221 A97
  N 880 45.0 390   B79   P 2910   220   B97
  E 870 32.3 307 280 Bi78 A-06 W 5407 3.6 443 385 S84
  G43 875 24.6 342 298 G75   V   4.3 385   C95

                         

                         
B-01 P 1763 10.9 175 227 * B-17 A 1258 12.1 218   GG81
B-03 A   <0.56     GH89   A 1255 10.5 204 171 TM81
  V   <0.55     vG87   N 1238 13.2 314 199 L73
B-11 G 2764 11.2     B87   V 1255 12.5     C95
B-16 N 2859 2.6 365 254 T98   W 1255 8.6     Ba78
  V   6.5 400   C95 B-19 P 5181 2.4 164 235 *
B-17 A 1257 9.0     DR78 B-21 P 3184 14.4 217 295 *

                         

                         
C-06 A   <1.0     G86 C-29 E 2619 7.7 502 432 H94
  A   <3.0     KS80 C-34 A   <0.62     BB77
C-11 IAR 370 35.1 103 80 BM85   A   <0.8     G83
  P 387 26.0     B88 C-35 A 1414 1.0 390 330 BB77
  G43 404 32.4     FT81   A 1592 0.72   256 DS96
  P 387 38.0 116   R82 C-37 G 1226 13.3 138 97 HG91
C-13 N 855 227.8 400 332 B80 C-38 A 3779       B85d
  G 851 129.2     DS83   A 3699 4.38 290 251 HR89
  G43 851 150.9     DS83 C-39 A 3922 4.1 547   SA83
  G 856 177.7 332 309 FT81 C-42 P 3289 15.6 403 356 A89
  G 852 150.3     R80 C-44 G 1289 3.2 140 112 HG91
  A 848 >52.0 324 306 S86   G 1225 10.5     RH91
  G 851 154.6 325   TC88   G 1225 10.4 230 130 HR89
  W 846 135 322 304 vD95 C-45 P 559 52.0 551 528 GW76
C-14 P   <10.4     H81   R 567 231 231   G80
C-18 N 1789 0.61 147 54 F90 C-46 N 5366 17.5 740 585 B88
  N 1744 0.17 118 98 MG98 C-49 A 4475 1.9 293 276 G81
C-24 A 6421 2.58 213 146 BG87 C-50 N 6556 2.0 564 548 T98
C-26 A 5480 1.3     B85c C-51 G   <4.5     HR89
  A 5496 2.32 493 436 BG86 C-69 A 2083 10.0 193 155 GH93
  A 5482 2.83   462 H97   A 2081 12.8 203 158 TM81
C-27 A 1969 6.6 196 169 HG84   A 2083 12.3 223   GG81
C-28 G 1476 33.5 319   AW86   A 2081 10.0 200   H81
  J 1473 31.1 318 287 D80   A 2083 10.0   159 KS80
  W 1476 29.4 319   K96   B 2081 14.1     H98
  G 1466 7.0   294 M94   E 2083 2.5   146 H95
  E 1488 42.1 313   WK91   N 2093 17.4 259 187 B75
  G 1476 33.5 319   HR89   V 2081       BK88

                         

                         
D-15 A 993 70.5     H82 D-35 G43   <8.3     B76
  E 992 63.1 229 173 B83   N 4720 3.6 470 330 D90
  G 989 113.2 200   H82   V   4.0     H94
  G 970 59.5 244 179 PS74 D-43 N 3455 4.1 575 565 T98
  G 992 63.1 229 173 HR89 D-44 A 2174 8.8     DS83
  N 994 62.9 250 183 B70   A 2178 5.4   160 G87
  W 987 62.3 258 176 M95   A 2281 18.0 450 388 L93
D-16 G   <3     DS83   A 2267   481   M82
D-19 A 7078 3.4 290   C83   A 2255 18.2 429   TW82
  A 7080 2.0 293   SA83   A 2174 8.8     DS83
  A 7067 3.5 352 289 B85c   G 2178 19.0     DS83
  A 7076 3.5   269 H97   G 2162 25.4 217 158 DR78
D-21 A,W   <2.2     S.3.2   G 2260 31.4 288 140 PS74
D-22 A   1.66     KS79   G 2162       RD76
D-23 G   <3.5     RH87   G 2193 23.2 220 135 S78
D-25 A   <1.8     B87   G43 2247 38.8     DS83
D-28 A 7298 -6.8 345 490 C87   J 2280 44.8     LD87
  A 7287 -4.2   173 G87   N 2230 42.9 335 135 B82
  A 7270 -5.9 570 360 B85 D-46 A 3086 4.0 274 239 L87
  A 7350 abs. 705 365 H83   A 3072 3.4 286 253 SK78
  V 7256 abs.   405 D82   G 3090 3.0 245 220 RH91




H I references and telescope codes to Table 3
A89 Aaronson et al. (1989) AW86 Armstrong & Wootton (1986) A97 Arnaboldi et al. (1997)
B85 Baan et al. (1985) BM85 Bajaja & Martin (1985) B76 Balick et al. (1976)
B72 Balkowski et al. (1972) Ba78 Balkowski (1978) B79 Balkowski (1979)
B97 Barnes et al. (1997) B88 Becker et al. (1988) BG86 Bicay & Giovanelli (1986)
BG87 Bicay & Giovanelli (1987) Bi78 Bieging (1978) BB77 Bieging & Biermann (1977)
B83 Bohnenstengel (1983) B88 Boissé et al. (1988) B85a Bothun et al. (1985a)
B85b Bothun et al. (1985b) B70 Bottinelli et al. (1970) B75 Bottinelli et al. (1975)
B80 Bottinelli et al. (1980) B82 Bottinelli et al. (1982) BK88 Brinks & Klein (1988)
B87 Bushouse (1987) C87 Chamaraux et al. (1987) C83 Chincarini et al. (1983)
C95 Cox et al. (1995) D80 Davies (1980) DS83 Davis & Seaquist (1983)
DR78 Dickel & Rood (1978) DR80 Dickel & Rood (1980) D82 Dickey (1982)
D90 Dupraz et al. (1990) DS96 DuPrie & Schneider (1996) FT81 Fisher & Tully (1981)
F90 Fouqué et al. (1990) G75 Gallagher et al. (1975) GW76 Gardner & Whiteoak (1976)
G87 Garwood et al. (1987) G83 Giovanardi et al. (1983) G81 Giovanelli et al. (1981)
G86 Giovanelli et al. (1986) GH89 Giovanelli & Haynes (1989) GH93 Giovanelli & Haynes (1993)
GG81 Gordon & Gottesman (1981) G80 Gosachinskii et al. (1980) H81 Hawarden et al. (1981)
H81 Haynes (1981) HG91 Haynes & Giovanelli (1991) H97 Haynes et al. (1997)
H98 Haynes et al. (1998) H83 Heckman et al. (1983) H94 Hibbard et al. (1994)
H94 Huchtmeier (1994) HR89 Huchtmeier & Richter (1989) H82 Hunter et al. (1982)
H95 Huchtmeier et al. (1995) K96 Kamphuis et al. (1996) K77 Knapp et al. (1977)
KS79 Krumm & Salpeter (1979) KS80 Krumm & Salpeter (1980) L73 Lauqué (1973)
L87 Lewis (1987) LD87 Lewis & Davies (1973) L93 Lu et al. (1993)
M94 Magri (1994) M98 Matthews et al. (1998) M82 Mirabel (1982)
M95 Mulder et al. (1995) PS74 Peterson & Shostak (1974) R82 Reif et al. (1982)
RH87 Richter & Huchtmeier (1987) RH91 Richter & Huchtmeier (1991) RD76 Rood & Dickel (1976)
R80 Rots (1980) S86 Schneider et al. (1986) S80 Shane (1980)
S84 Schechter et al. (1984) S78 Shostak (1978) SK78 Silvergate & Krumm (1978)
SA83 Sulentic & Arp (1983) T98 Theureau et al. (1998) TM81 Thuan & Martin (1981)
TW82 Thuan & Wadiak (1982) TC88 Tifft & Cocke (1988) vD95 van Driel et al. (1995)
vG87 van Gorkom et al. (1987) WK91 Wunderlich & Klein (1991) * This paper

         
A Arecibo 305-m AT Australia Telescope E Effelsberg 100-m
G Green Bank 90-m G43 Green Bank 43-m IAR I.A.R. 30-m
J Jodrell Bank 76-m N Nançay 94-m equiv. P Parkes 64-m
R RATAN 600 V VLA W Westerbork


D-22 = NGC 4643. (A,E,G,N) Very faint, disclike feature aligned with the major axis of this otherwise normal-looking barred spiral, extending to about three times the optical radius of the inner galaxy. Has a LINER-type optical spectrum (Boulesteix et al. 1988; Ho et al. 1997; Keel 1983). Only nuclear line emission was found in the H$\alpha$ imaging by Pogge & Eskridge (1993) and only very faint, patchy circumnuclear H$\alpha$ emission by Pogge (1989). Optical and near-infrared imaging (Ohta et al. 1990; Shaw et al. 1995) suggest the presence of secondary, nuclear bar. A projected maximum stellar rotation velocity of 90  kms-1 was derived from long-slit spectroscapy at 4 position angles by Bettoni & Galletta (1997). The Green Bank H I line profile is centered at a 250  kms-1 lower radial velocity than the optical redshift of the PRG and the Nançay and Effelsberg H I velocity, and the Green Bank profile width (140 kms-1) is two times narrower. According to Paper I, the Green Bank detection is "probably associated with a small companion galaxy of unknown redshift at 20' distance, which nevertheless is a very gas-poor system ( ${M}_{\rm HI}$/LB = 0.02 ${M}_\odot$/ $L_{\odot,B}$)''. No other galaxies were found in the Nançay search area.

D-23 = NGC 4753. (E,G,G43,N,P) Appears to be a good candidate for the formation of an X- or box-shaped galaxy by accretion (PRC); short exposures show a extensive, seemingly chaotic pattern of dust lanes (Sandage 1961), which was matched, however, by a precessing disc model (Steiman-Cameron et al. 1992). Rising H$\alpha$ rotation curve, flattening out beyond 10'' radius; LINER-type nuclear spectrum (Reshetnikov & Combes 1994). Listed as member of group LGG 315 (Garcia 1993), alias the NGC 4643 and NGC 4753 groups, and group 41 from Huchra & Geller (1982). No other objects found within the Nançay search area. The Nançay and Effelsberg profile parameters are totally different; the narrow peak seen at Effelsberg does not even correspond to a peak in the broad, and weak, Nançay profile. Published H I upper limits only, the best is 3.5 Jy kms-1(see Table 3 and Huchtmeier & Richter 1989).

D-24 = ESO 575-G44 (E) Very close pair of galaxies of 15.06 and 13.53 mag, respectively. The optical redshift of the system (9066 $\pm$ 90 kms-1) is based on two measurements (Dressler 1991 and Fairall et al. 1992). This value lies outside the range of the Effelsberg H I observations, where a 390 kms-1 wide profile centered on 2806 kms-1 was detected instead. No other catalogued galaxies were found within the Effelsberg beam area. The Effelsberg detection therefore appears to be spurious.

D-25 = UGC 8387 = IC 883. (A,E,G,N) This objects shows two linear, one-sided and almost perpendicular tidal tails protruding from the centre in the optical and near-infrared (Smith et al. 1995, 1996; Stanford & Bushouse 1991, PRC). It is quite infrared luminous. Near-infrared spectra and H$\alpha$ rotation curve: see Smith et al. (1996). Has a LINER optical spectrum (Kim et al. 1995; Veilleux et al. 1995). Near infrared spectrum: see Puxley (1994); near-infrared imaging: see Zhou et al. (1993). In our survey, H I emission was observed at Green Bank only. Observations with the much smaller ( $3'\,\hspace{-1.7mm}.\hspace{.0mm}8$ diameter) Arecibo beam show a broad, triple-peaked absorption feature against the continuum (Mirabel & Sanders 1988), while Bushouse (1987) measured an upper limit of 1.8 Jy kms-1. No other galaxies were found within the Nançay search area. D-28 = NGC 6240. (A,E,G,N) This galaxy is a merger product with a luminosity profile similar to that of an elliptical and it is a superliminous IRAS galaxy. In its inner parts many crossed optical loops can be seen, while the outer regions show an extensive set of shells. The H I emission line spectrum may be influenced by absorption against the strong continuum, since it is a strong radio source. CCD images: see PRC. It has a LINER optical spectrum (Goldader et al. 1997; Kim et al. 1995; Rieke et al. 1985; Veilleux et al. 1995); stellar kinematics: see Lester (1994) The object contains a strong continuum source (650 mJy at 21 cm), and thus care has to be taken in accurately determining the radio telescope's passband in both polarisations used; we did this at Nançay using a strong quasar. An absorption profile was detected at Nançay as well as in several Arecibo and VLA studies (see Table 3): only the Arecibo profile of Garwood et al. (1987) has a FWHM (173 kms-1) comparable to our Nançay measurement, the others are considerably broader (average 405 kms-1). The OH lines also show an absorption profile (Baan et al. 1985, 1992). No H2O megamaser activity was detected (Braatz et al. 1997). Near-infrared imaging and spectrum: see Doyon et al. (1994), Rieke et al. (1985), Zhou et al. (1993). No other galaxies were found within the Nançay search area.

D-43 = ESO 510-G13. (E,G,N) Boxy system with a very thin optical disc and a dust lane along its minor axis. It was separated as two sources by the automatic ESO-LV surface photometry software. Other published Nançay detection: see Theureau et al. (1998). No other galaxies were found within the Nançay search area.

3.3 Results - comparison with the Green Bank and Effelsberg survey data and other published data

Basic H I line data obtained for our PRG survey at Green Bank, Effelsberg and Nançay are given in Table 2 for all 74 galaxies of the combined PRG H I sample. The Green Bank and Effelsberg data were taken straight from Papers I and II, respectively. The velocity resolution used at Nançay to determine the H I line parameters or upper limits is 15.8 kms-1 for the objects with previously known redshift and 19.0 kms-1 for the others.

The estimated upper limits to the integrated H I line fluxes listed in Table 2 are 3$\sigma$ values for an assumed 250  kms-1 wide flat-topped profile; the double upper limits listed for objects without previously known redshift are for the low (340-5207  kms-1) and high ( 5140-10007  kms-1) Nançay velocity search ranges, respectively.

Most PRG objects observed are rather faint in H I, as is obvious from the signal-to-noise ratio of many of the H I profiles obtained with any of the three telescopes used for our survey. The average integrated line flux of the galaxies detected at Nançay, and plotted in Fig. 2, is only 1.7 Jy kms-1. This often makes it difficult to determine really accurate profile parameters from a spectrum measured with any single telescope. We will therefore have to rely on a comparison of all available profiles per galaxy in order to derive the most reliable H I parameters possible, which can then be used to calculate derived quantities - these data will be presented and analysed in the next paper in these series (van Driel et al., in preparation).

A potentially important factor in the comparison of profiles of the same object is the significant difference in beam size for the telescopes used: 21' round at Green Bank, 12' round at Effelsberg, and $4'\times22'$ ( $\Delta\alpha\times\Delta\delta$) at Nançay for $\delta\le 30$$^\circ$. A larger beam size may in principle lead to (1.) higher H I masses measured for galaxies with extended H I distributions, and (2.) a higher chance of confusion by other galaxies in the beam area, as detailed in the present paper (Sect. 3.2) and in the Appendix to Paper I. Another important factor is that recent projects at the three sites have shown that Nançay appears to be better protected against radio frequency interference in the 21-cm band than Green Bank and Effelsberg, avoiding spectral contamination - clear evidence of interference is shown by, e.g., the very broad Effelsberg profiles in Fig. 3.

A comparison of the integrated H I line fluxes of objects detected with different telescopes for our PRG survey, as well as between our Nançay and published Arecibo data (Fig. 2) shows a considerable scatter in all plots. On average, values measured at Nançay are generally about 2 times lower than those measured at Green Bank or at Effelsberg - of the 3 Nançay values which are about twice as high as the Effelsberg measurements (for C-35, C-49 and D-43) only the C-35 measurement appears to be due to confusion. On the other hand, the Nançay-Arecibo comparison shows an agreement between most measurements; confusion within the Nançay beam is the cause of the considerably higher H I flux measured at Nançay for C-35, so the Nançay and Arecibo data appear to be consistent. The comparison of our Green Bank and Effelsberg values show clustering around a ratio of 1.

Similar comparisons (Matthews et al. 1998; Matthews & van Driel 2000) of recent Nançay line fluxes of two samples of unresolved galaxies with (much) stronger H I emission, observed and reduced in exactly the same way as our PRG data, does not show a clear systematic difference with line fluxes measured at other sites (primarily Green Bank and Arecibo) by other authors, or with fluxes measured earlier at Nançay by other authors. In conclusion, the cause of the Nançay-Green Bank/Effelsberg flux discrepancy found in our survey is not clear.

A comparison of the central H I line velocities measured with different telescopes (see Table 3) shows that most 21-cm radial velocities are rather accurate: the external error is of the order of 20 to 30 kms-1, compared to the 16 kms-1 velocity resolution of the Nançay data. Some large discrepancies are found, though, especially in the comparison between Effelsberg and Green Bank data, where 5 (out of 19) profiles of commonly observed objects have differences between 210 and 400 kms-1, but these seem to be due to confusion with nearby galaxies and/or radio interference signals (see the Notes in Sect. 3.2).

A comparison (Fig. 3) of H I linewidths determined at 20% of the peak intensity value, $\Delta$V20, in general shows good agreement, even without applying corrections for instrumental resolution. In the Nançay-Green Bank comparison, only one object (C-50) shows a much larger Nançay linewidth, which is consistent with the Effelsberg data. In the Nançay-Effelsberg comparison, the largest discrepancies (the broader Nançay profile of C-39) can be explained by confusion with nearby group members, while the broad width of the C-28 Nançay profile is consistent with 5 literature values. In the Green Bank-Effelsberg comparison, the most prominent exceptions are 5 galaxies (C-26, 38, 46 and 50, and D-22) for which the discrepancies appear to be due to radio interference or confusion (see Sect. 3.2). In conclusion, the discrepancies in measured line widths can be explained by radio interference or confusion with other galaxies.

Acknowledgements
We would like to thank the staff of the Nançay and ARPEGES departments of the Paris Observatory for their support with the observations and the data reduction, especially Dr. E. Gérard. We have made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the U.S. National Aeronautics and Space Administration, as well as the Lyon-Meudon Extragalactic Database (LEDA) supplied by the LEDA team at the CRAL-Observatoire de Lyon (France). The Unité Scientifique Nançay of the Observatoire de Paris is associated as Unité de Service et de Recherche USR No. B704 to the French Centre National de Recherche Scientifique (CNRS). Nançay also gratefully acknowledges the financial support of the Région Centre in France.

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