W. van Driel^1,2 - P. Marcum³ - J. S. Gallagher III⁴ - E. Wilcots⁴ - C. Guidoux⁵ - D. Monnier Ragaigne¹

1 - DAEC, UMR CNRS 8631, Observatoire de Paris, Section de Meudon, 5 place Jules Janssen, 92195 Meudon Cedex, France
2 - Unité Scientifique Nançay, USR CNRS B704, Observatoire de Paris, 18330 Nançay, France
3 - Department of Physics and Astronomy, Texas Christian University, Box 298840, Fort Worth, TX 76129, USA
4 - Astronomy Department, University of Madison-Wisconsin, 475 N. Charter St., Madison WI 53706-1582, USA
5 - Faculté des Sciences et des Techniques, Université de Tours, Avenue Monge, 37000 Tours, France

Abstract
At Nançay, 21-cm H I line observations were made of 15 spiral-dominated loose groups of galaxies, divided into two samples: an "interacting'' sample containing at least one pair of interacting galaxies, and a "control'' sample having no optical evidence of interactions or morphological disturbances among the group members. The interacting sample consists of 62 galaxies representing 9 different groups, and the control sample contains 40 galaxies representing 6 groups. Of the 91 galaxy and galaxy pairs observed, 74 were detected, while upper limits were placed on the remaining 17 objects. These homogeneous H I data, which will be used in future analyses, provide comparative information on the H I content of groups and serve as a probe of the vicinity of the target spirals for H I clouds or very low surface brightness gas-rich galaxies.

Key words: galaxies: distances and redshifts - galaxies: general - galaxies: interactions - galaxies: ISM - radio lines: galaxies

1 Introduction

However, the non-detection of a hot, intragroup medium within spiral-rich galaxy groups does not preclude those groups from being real physical systems. The dynamical evolution of a bound group will influence the temperature of the intragroup medium (Mulchaey & Zabludoff 1998), analogous to correlations such as that seen between L_x, T_x and velocity dispersion in galaxy clusters (Xue & Wu 2000). Some studies (Marcum 1994; Hickson et al. 1988; Nolthenius 1993) show that, on average, spiral-rich groups have lower velocity dispersions as compared to elliptical-dominated systems. This reduction in the thermal energy being deposited into the intragroup medium of spiral-rich groups predicts that the extant intergalactic gas in these systems would most likely exist mainly in the form of neutral hydrogen. Indeed, some groups have been found to be rich in neutral hydrogen which is tied up in either low surface brightness dwarfs (Gallagher et al. 1995) or H I clouds (e.g., Schneider et al. 1986b; Hoffman et al. 1992).

**Table 1:** Group properties.
GH	NGal	RA	Dec.	${<}V_{\rm vir}{>}$	$\sigma_V$	d	$B\rm _T$
No.		(2000.0)		(kms^-1)	(kms^-1)	(Mpc)	(mag)
(1)	(2)	(3)		(4)	(5)	(6)	(7)

Interacting group sample
45	4	09 16.8	41 17	1833	150	24.4	12.4
58	10	10 19.5	20 46	1319	217	17.6	10.1
67	8	10 51.4	33 35	1814	174	24.2	10.7
86	3	11 37.6	32 09	2806	41	37.4	12.4
92	11	11 54.9	25 29	4361	518	58.1	11.8
126	6	13 56.1	37 40	3532	357	47.1	11.3
141	13	14 23.9	36 01	3683	461	49.1	10.6
153	3	15 26.3	41 17	2790	45	37.2	12.7
156	4	15 34.8	15 30	2040	93	27.2	11.6

Control group sample
49	3	09 50.5	43 44	4889	65	65.2	12.3
57	4	10 13.6	03 21	1248	60	16.6	10.6
89	7	11 42.5	09 46	6118	180	81.6	11.8
118	3	13 25.4	36 14	5537	254	73.8	12.7
123	17	13 51.3	40 53	2600	158	34.6	9.8
155	6	15 34.0	43 16	5933	149	79.1	12.1

Note: mean group velocities $V_{\rm vir}$ were corrected for Virgocentric infall, and H₀=75 kms^-1 Mpc^-1 was assumed.

The dynamical evolution of a loose group is undoubtedly actuated by multiple minor mergers between these gas-rich satellites and larger group members (Haynes et al. 2000), as well as the more dramatic interactions between the large mass galaxies. While the ramifications of such encounters can be found across the spectrum (such as H $\alpha$ , Band thermal infrared luminosity enhancements resulting from the ensuing star formation activity, and optical morphological signatures such as tidal tails and bridges), there is evidence that the disruptions in the gaseous disk is long-lived. For example, the presence of X-shaped structures seen in some peculiar S0 galaxies (Mihos et al. 1995), and the counter-rotating disks seen in some early-type spirals (Corsini et al. 1998; Jore et al. 1996) in otherwise optically normal-looking galaxies is interpreted as the aftermath of minor mergers. The outer regions of gas disks are vulnerable to warps and other distortions created by a close encounter with a passing galaxy, and are not likely to rebound quickly once disturbed. The denser regions of a galaxy cluster environment, where galaxy interactions likely occur with high frequency, impact the H I properties of the cluster members even more severely: H I disks in galaxies located closest to the cluster core are more likely to be gas-deficient, truncated and asymmetrical. These trends are found even in loose clusters (Chamaraux et al. 1980; Haynes et al. 1985). Thus, peculiarities in the H I properties of a galaxy serve as a "fossil'' record of past galaxy-galaxy interactions. Groups of galaxies which are dynamically evolved systems, whose members have experienced multiple disruptive interactions, would be expected to harbor a higher frequency of H I peculiarities. Therefore, a comparative analysis of H I properties can be used as relative dynamical "age'' indicator for groups of galaxies.

Based on the idea that the neutral hydrogen properties is sensitive to environment, our main motivation for this single-dish H I line observational study of loose groups is to test whether "interacting'' groups, which we define as groups hosting at least one pair of optically disturbed interacting galaxies, show evidence for prolonged histories of galaxy-galaxy interactions among the other group members. In the "interacting'' groups, most of the galaxy members (with, of course, the exception of the interacting pair itself) show no unusual optical features indicative of past tidal interactions. Either (1) the group is a truly youthful kinematical system, having not yet experienced multiple tidal interactions within the system, or (2) the aftermath of previous galaxy-galaxy interactions among the other group members has left no signatures which are still optically visible. A comparative analysis of asymmetries in the H I line profile shapes (however with caution: see Richter & Sancisi 1994) and the total H I content for the galaxy groups can help distinguish between these two possibilities. Understanding the kinematical evolution of galaxy groups is particularly important, in light of HST observations of galaxy groups at very high redshift.

Though oft-cited H I mappings of galaxy groups frequently show tidal H I features, it would be misleading to draw the conclusion from these examples that such features are commonplace. Generally, these observations cover only the inner parts of groups, often centered on an interacting galaxy pair. Examples are the Arecibo maps of groups by Haynes et al. (1981), showing tidal features from at least one group member in 6 of the 15 groups mapped, and the VLA maps of the M81 group by Yun et al. (1994). Observations searching for H I throughout the volume covered by groups are rare, due to the large apparent size of nearby groups. Systematic searches for H I clouds in groups were made at Arecibo by Lo & Sargent (1978) in the nearby M 81, NGC 1023 and CVnI groups (the latter was also covered in the Nançay blind H I line search by Kraan-Korteweg 1999) and by Zwaan (2000, 2000) in 6 groups at redshifts of 1800-3000 km s^-1 (NGC 5798, 5962, 5970, 6278, 6500 and 6574) with properties similar to those of the Local Group of galaxies. All H I emission features detected in these searches could unambiguously be associated to optically identified galaxies or to a previously known H I tidal feature in the NGC 6500/01 pair. The 5 $\sigma$ H I mass detection limit for an H I cloud with a linewidth of 10 km s^-1 is about $8\times 10^{6}$ ${M}_\odot$ at the average distance of 30 Mpc (for H₀=75 km s^-1 Mpc^-1) for the groups in Zwaans' study. For comparison, the detection limit of the present H I survey is about 4 times higher.

In this paper we present a new homogeneous set of H I 21-cm line observations for galaxies in 15 loose groups: 9 with at least one pair of strongly interacting galaxies and 6 without optical indicators of tidal interactions. The galaxy group sample selection is described in Sect. 2, where the basic optical properties of the program galaxies are listed as well. The observations and data reduction are described in Sect. 3, and the H I results are presented in Sect. 4, including notes to invidual galaxies for the interpretation of the 21-cm line data and a comparison of the observed global line parameters with published values. These H I data will, together with our optical and near-infrared data on the groups, provide the basis for a discussion of evolution within galaxy groups that is planned for a future paper (Marcum et al., in preparation).

2 The observed galaxy group sample

The "interacting'' group sample comprises 62 galaxies in 9 groups, of which 8 galaxies were not previously observed in H I and 4 were not detected. The "control'' sample comprises 40 galaxies in 6 groups, of which 3 were not previously observed and 6 were not detected in the 21-cm line. Basic properties of the program objects are presented in Table 1.

Listed in the 7 columns of Table 1 are (1) Geller & Huchra (1983) group designation number; (2) total number of galaxy members in group; (3) right ascension and declination of the group, from Geller & Huchra (1983), converted from epoch B1950.0 to J2000.0; (4) mean recession velocity in km s^-1 of the group members, using optical radial velocities from the LEDA database and corrected to the Galactic Standard of Rest, following de Vaucouleurs et al. (1991, hereafter RC3); (5) velocity dispersion of group, using mean optical radial velocities from the LEDA database; (6) adopted distance in Mpc, derived from the mean recession velocity of the group, corrected for Virgocentric infall, following LEDA, and using a Hubble constant of 75 km s^-1 Mpc^-1; (7) total apparent B magnitude of group members, from Geller & Huchra (1983).

Tables 2 and 3 list basic optical properties of the target objects. The 9 columns of Tables 2 and 3 are: (1) GH83 group designation number; (2) galaxy identification; (3) right ascension and declination of the galaxy centroid, computed from data taken from RC3; (4) morphological type, from LEDA and NED; (5) apparent $B\rm _T$ magnitude, from LEDA; (6) galaxy isophotal B band diameter at the 25 mag arcsec^-2 level, from LEDA; (7) axial ratio in the B band, from LEDA; (8) optical recessional velocity, from LEDA; (9) error in recessional velocity, from LEDA.

3 Observations and data reduction

**Table 2:** Basic optical data for the interacting group sample.
GH	Ident.	RA	Dec.	Morphol. Class.		$B\rm _T$	D₂₅	axial	$V_{\rm opt}$	err
No.		(2000.0)		LEDA	NED	mag	(')	ratio	(kms^-1)	(kms^-1)
(1)	(2)	(3)		(4)		(5)	(6)	(7)	(8)	(9)

45	NGC 2798*	09 17 22.9	42 00 02	SBa	SB(s)ap	13.03	2.7	0.35	1733	64
	NGC 2799*	09 17 31.4	41 59 39	SBm	SB(s)m?	13.96	1.8	0.29	1863	72
	NGC 2844	09 21 48.0	40 09 07	Sa	SA(r)a:	13.72	1.7	0.44	1495	16
	NGC 2852	09 23 14.2	40 09 53	SBa	SAB(r)a?	13.98	1.5	0.93	1821	54

58	NGC 3162	10 13 31.9	22 44 23	SBbc	SAB(rs)bc	12.20	3.1	0.83	1456	56
	NGC 3177	10 16 34.4	21 07 29	Sb	SA(rs)b	13.01	1.5	0.76	1220	56
	NGC 3185	10 17 38.6	21 41 19	SBa	(R)SB(r)a	12.82	1.7	0.6	1237	26
	NGC 3187	10 17 47.5	21 52 25	SBc	SB(s)cp	13.72	2.5	0.41	1582	28
	NGC 3189	10 18 05.7	21 49 59	Sa	SA(s)ap	11.86	4.6	0.42	1289	31
	NGC 3193	10 18 25.0	21 53 42	E	E2	11.70	2.2	0.9	1378	27
	NGC 3213	10 21 17.7	19 39 07	Sbc	Sbc:	14.13	1.0	0.79	1412	50
	NGC 3226*	10 23 27.4	19 53 55	E	E2:p	12.34	2.6	0.87	1325	72
	NGC 3227*	10 23 31.4	19 51 48	SBa	SAB(s)p	11.28	5.4	0.69	1145	54
	NGC 3239	10 25 05.5	17 09 35	Irr	IB(s)mp	11.71	4.5	0.54	830	52

67	UGC 5870	10 45 58.6	34 57 53	S0	S0?	14.27	1.1	1.00	2032	50
	NGC 3381	10 48 25.0	34 42 44	SBb	SBp	12.77	2.0	0.92	1506	33
	NGC 3395*	10 49 49.4	32 58 51	SBc	SAB(rs)cdp:	12.39	1.7	0.56	1634	39
	NGC 3396*	10 49 56.1	32 59 22	SBm	IBmp	12.48	2.7	0.42	1666	36
	NGC 3424	10 51 46.6	32 54 02	SBb	SB(s)b:?	13.07	2.7	0.28	1420	35
	NGC 3430	10 52 10.9	32 57 09	SBc	SAB(rs)c	12.21	4.1	0.55	1577	77
	NGC 3442	10 53 08.2	33 54 36	Sa	Sa?	13.80	0.6	0.77	1713	52
	UGC 6070	10 59 46.5	33 23 32	Sm	S?	13.45	0.7	0.77	1861	60

86	UGC 6545	11 33 44.5	32 38 04	SBb	S?	14.46	1.2	0.37	4278	1885
	NGC 3786*	11 39 42.4	31 54 35	SBa	SAB(rs)ap	13.44	2.0	0.55	2596	296
	NGC 3788*	11 39 44.0	31 55 58	SBab	SAB(rs)abp	13.33	1.6	0.26	2486	150

92	NGC 3902	11 49 18.9	26 07 22	SBbc	SAB(s)bc:	13.76	1.6	0.81	3628	50
	NGC 3920	11 50 06.3	24 55 15		S?	14.01	1.0	0.95	3611	37
	UGC 6806	11 50 19.7	25 57 42	Sc	Sp	14.17	1.9	0.32	3757	50
	NGC 3944	11 53 05.5	26 12 28	E-S0	S0-:	14.12	1.4	0.77	3638	31
	IC 746	11 55 34.6	25 53 19	Sbc	Sb	14.36	1.1	0.30	5000	50
	NGC 3987	11 57 21.2	25 11 41	Sb	Sb	13.90	2.2	0.19	4533	28
	NGC 3997	11 57 47.3	25 16 18	SBb	SBbp	14.02	1.6	0.55	4742	42
	NGC 4005	11 58 10.3	25 07 18	S?	Sb	13.89	1.2	0.59	4425	65
	NGC 4015A*	11 58 43.3	25 02 40	Sc	E	14.15	0.9	0.23	4780	57
	NGC 4015B*	11 58 43.1	25 02 35	Sab	S?	12.81	1.4	0.66	4347	44
	NGC 4022	11 59 01.1	25 13 19	S0	SAB0⁰:	14.24	1.3	0.95	4340	88

126	NGC 5341	13 52 31.4	37 48 58	SBd	S?	14.08	1.3	0.42	3740	60
	NGC 5351	13 53 28.1	37 54 52	SBb	SA(r)b:	13.00	2.9	0.55	3845	66
	NGC 5378	13 56 50.6	37 48 00	SBa	(R')SB(r)a	13.67	2.7	0.83	3017	42
	NGC 5380	13 56 56.7	37 36 34	E-S0	SA0^-	13.26	1.9	1.00	3116	126
	NGC 5394*	13 58 33.8	37 27 18	SBb	SB(s)bp	13.69	1.7	0.66	3442	88
	NGC 5395*	13 58 38.3	37 25 32	Sb	SA(s)bp	12.12	2.6	0.53	3505	35

141	NGC 5529	14 15 34.1	36 13 36	Sc	Sc	12.74	6.5	0.11	2957	60
	NGC 5533	14 16 07.6	35 20 42	Sab	SA(rs)ab	12.70	3.2	0.60	3781	56
	NGC 5544*	14 17 02.4	36 34 21	S0-a	(R)SB(rs)0/a	13.97	1.1	0.89	3106	75
	NGC 5545*	14 17 05.4	36 34 34	Sbc	SA(s)bc:	14.90	1.0	0.34	3139	85
	NGC 5557	14 18 26.2	36 29 38	E	E1	11.91	2.3	0.79	3221	43
	NGC 5589	14 21 24.7	35 16 15	SBa	SBa	14.20	1.1	1.00	3391	50
	NGC 5590	14 21 38.0	35 12 19	S0	S0	13.42	1.8	1.0	3242	50
	NGC 5596	14 22 29.2	37 07 17	S0	S0	14.41	1.1	0.74	3265	351
	NGC 5614	14 24 08.2	34 51 27	Sab	SA(r)abp	12.54	2.4	0.83	3872	41
	NGC 5656	14 30 25.1	35 19 12	Sab	Sab	12.64	1.9	0.77	3150	9
	NGC 5675	14 32 39.8	36 18 12	SBb	S?	13.72	2.8	0.35	4066	108
	NGC 5684	14 35 49.8	36 32 35	S0	S0	13.59	1.6	0.85	4082	31
	NGC 5695	14 37 23.0	36 34 15	SBa	SBb	13.58	1.5	0.7	4168	115

153	NGC 5929*	15 26 05.5	41 40 17	Sa	Sab:p	14.06	1.0	0.95	2514	33
	NGC 5930*	15 26 07.8	41 40 39	SBab	SAB(rs)bp	13.53	1.8	0.46	2664	48
	UGC 9858	15 26 40.9	40 33 52	SBbc	SABbc	13.83	4.3	0.19	2624	8

156	NGC 5951	15 33 43.1	15 00 27	SBc	SBc:	13.47	3.6	0.22	1670	63
	NGC 5953*	15 34 32.4	15 11 42	S0-a	SAa:pec	13.13	1.8	0.74	2061	90
	NGC 5954*	15 34 34.8	15 12 12	SBc	SAB(rs)cd:p	13.12	1.3	0.48	2034	81
	NGC 5962	15 36 31.7	16 36 32	Sc	SA(r)c	12.03	3.0	0.72	1993	56

Note: Asterisks (*) in this and following tables denote target pairs which are confused within a single Nançay beam (see Table 6, also).

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 at approximately 20' E of the target position. The autocorrelator was divided into two pairs of cross-polarized receiver banks, each with 512 channels and a 6.4 MHz bandpass. This yielded a channel spacing of 2.64 km s^-1, for an effective velocity resolution of $\sim$ 3.3 km s^-1 at 21-cm, which was smoothed to a channel separation of 13.2 and a velocity resolution of 15.8 km s^-1 during the data reduction, in order to search for faint features. The center frequencies of the two banks were tuned to the known redshifted H I frequency of the target. Total integration times were up to 5 hours per galaxy, depending on the strength of the source (see Tables 4 and 6).

We reduced our H I spectra using the standard DAC and SIR spectral line reduction packages available at the Nançay site. With this software we subtracted baselines (generally third order polynomials) and averaged the two receiver polarizations. To convert from units of $T_{\rm sys}$ to flux density in mJy we used the calibration procedure described in Matthews et al. (2000), see also Matthews et al. (1998) and Matthews & van Driel (2000). This procedure yields an internal calibration accuracy of about $\pm$ 15% near the rest frequency of the 21cm line, where the observations presented here were made.

4 Results

Derived Nançay H I profile parameters for the target galaxies are listed in Tables 4 and 6. For each group of galaxies, a single distance was assumed (see Table 1), calculated using a Hubble constant of 75 km s^-1 Mpc^-1 and the mean radial velocities of the group members, corrected for Virgocentric infall. No corrections have been applied to these values for, e.g., instrumental resolution or cosmological stretching (e.g., Matthews et al. 2000).

Listed in the 9 columns of Tables 4 and 6 are: (1) GH83 group designation number; (2) galaxy identification; (3) right ascension and declination of the galaxy centroid taken from the RC3; (4) recessional velocity, as derived from Nançay observations and corrected to the Galactic standard of rest, as well as its estimated uncertainty; (5) integrated neutral hydrogen line flux; (6) neutral hydrogen line full width measured at the 50% level of the peak flux density; (7) neutral hydrogen line full width measured at the 20% level of the peak flux density; (8) root-mean-square of the flux density, measured outside the emission line profile; (9) neutral hydrogen mass, using the adopted distance as given in Table 1; (10) luminosity in the B band, using the adopted distance as given in Table 1; (11) neutral hydrogen mass to B band luminosity ratio.

We estimated the uncertainties, $\sigma_{V_{\rm HI}}$ , in the central H I velocities following Fouqué et al. (1990):

4.1 Notes to individual galaxies

**Table 3:** Basic optical data for the control group sample.
GH	Ident.	RA	Dec.	Morphol. Class.		$B\rm _T$	D₂₅	axial	$V_{\rm opt}$	err
No.		(2000.0)		LEDA	NED	mag	(')	ratio	kms^-1	kms^-1
(1)	(2)	(3)		(4)		(5)	(6)	(7)	(8)	(9)

49	NGC 2998	09 48 43.6	44 04 52	SBc	SAB(rs)c	13.10	2.9	0.48	4767	19
	NGC 3009	09 50 10.5	44 17 40	Sc	S?	13.36	0.8	0.93	4604	50
	UGC 5295	09 52 54.1	42 50 55	SBb	SAB(s)b	14.26	2.1	0.56	4805	40

57	NGC 3156	10 12 41.1	03 07 50	S0	SO:	13.07	1.9	0.62	1230	89
	NGC 3165	10 13 31.4	03 22 32	Sm	SA(s)dm	14.49	1.4	0.49	1317	50
	NGC 3166	10 13 44.9	03 25 31	S0-a	SABO^-a	11.22	4.7	0.46	1329	75
	NGC 3169	10 14 14.3	03 28 08	Sa	SA(s)ap	11.04	4.6	0.56	1253	46

89	UGC 6617	11 39 17.5	09 57 48	S0	S0?	14.28	0.9	0.36	6228	31
	NGC 3817	11 41 53.1	10 18 07	S0-a	SB0/a	14.27	0.7	0.76	6102	32
	NGC 3822*	11 42 11.3	10 16 40	S0	Sb	14.10	0.8	0.60	6132	33
	NGC 3825*	11 42 23.7	10 15 52	SBa	SBa	13.93	0.9	0.81	6436	132
	IC724	11 43 34.7	08 56 31	Sa	Sa	13.49	2.3	0.40	5959	16
	NGC 3843	11 43 54.1	07 55 32	S0-a	S0/a	14.00	1.0	0.45	5908	50
	NGC 3839	11 43 54.4	10 46 59	Sd	Sdm:	13.60	1.0	0.51	5920	45

118	NGC 5141	13 24 51.6	36 22 40	S0	S0	13.80	1.7	0.76	5201	101
	NGC 5142	13 25 01.3	36 23 58	S0	S0	14.20	1.3	0.67	5235	65
	NGC 5149	13 26 09.7	35 56 04	SBbc	SBbc	13.90	1.5	0.64	5601	49

123	NGC 5289	13 45 09.2	41 30 11	SBab	(R)SABab:	13.95	1.6	0.31	2446	51
	NGC 5290	13 45 19.2	41 42 55	Sbc	Sbc:	13.29	3.7	0.27	2544	48
	NGC 5297	13 46 24.1	43 52 25	SBc	SAB(s)c:	12.39	5.5	0.23	2492	106
	NGC 5311	13 48 55.9	39 59 07	S0-a	S0/a	13.59	2.6	0.81	2698	40
	UGC 8736	13 49 03.9	39 29 56	Sc	S?	14.25	1.3	0.42	2404	50
	NGC 5313	13 49 44.7	39 59 10	Sb	Sb?	12.71	1.7	0.56	2597	44
	NGC 5320	13 50 20.5	41 22 06	SBc	SAB(rs)c:	12.96	3.6	0.49	2646	65
	NGC 5326	13 50 50.7	39 34 29	Sa	SAa:	12.90	2.2	0.54	2540	68
	NGC 5336	13 52 10.9	43 14 34	Sc	Scd:	13.57	1.4	0.89	2297	60
	NGC 5337	13 52 23.1	39 41 15	S?	S?	13.35	1.7	0.48	2208	46
	NGC 5350*	13 53 21.5	40 21 48	SBbc	SB(r)b	12.23	2.7	0.80	2322	61
	NGC 5354*	13 53 26.6	40 18 16	S0	E2	12.40	1.7	0.87	2681	244
	NGC 5353	13 53 26.8	40 17 03	S0	S0	11.97	1.9	0.71	2170	103
	NGC 5355	13 53 45.9	40 20 17	S0	E3	13.98	0.6	0.64	2422	38
	NGC 5362	13 54 53.5	41 18 51	Sb	Sb?p	13.20	2.2	0.44	2228	45
	NGC 5371	13 55 40.5	40 27 44	SBbc	SAB(rs)bc	11.38	4.2	0.81	2570	40
	NGC 5383	13 57 05.2	41 50 44	SBb	(R')SB(rs)b:p	12.10	2.7	0.81	2227	26

155	NGC 5934	15 28 12.4	42 55 49	S?	S?	14.60	0.7	0.47	5600	39
	NGC 5945	15 29 45.2	42 55 14	SBab	SB(rs)ab	13.80	2.6	0.85	5521	50
	IC4562	15 35 57.6	43 29 40	E	E?	13.81	1.2	1.00	5666	145
	IC4564*	15 36 27.0	43 31 08	Sc	S?	14.41	1.3	0.35	5669	39
	IC4566*	15 36 42.6	43 32 24	Sab	Sab	14.11	1.6	0.64	5608	47
	IC4567	15 37 13.3	43 17 54	Sc	Scd?	13.51	1.4	0.71	5775	40

Note: Asterisks (*) in this and following tables denote target pairs which are confused within a single Nançay beam (see Table 7, also).

We have summarized previously-published results of single-dish H I observations as well as of interferometric H I line imaging of galaxies and groups from the sample (see also the catalogue of H I maps by Martin 1998). Global profile parameters derived from these data are given in Tables 6 and 7, where the following columns are listed, while the keys to the telescopes and references used in these two tables are given in Table 8:

(1) GH83 group designation number; (2) galaxy identification; (3) mean velocity of the H I line profiles; (4) integrated line flux of the H I profiles; (5) H I line width measured at the 50% level of the peak flux density; (6) H I line width measured at the 20% level of the peak flux density; (7) telescope used (see Table 8); (8) literature reference (see Table 8).

For some objects, extended H I emission may have been missed by the single Nançay profile pointed towards the galaxy's centre. To assess which H I masses may be underestimated, we have assumed the H I diameters to be 1.25 times as large the optical D₂₅ dimensions, a rule-of-thumb from interferometric H I line imaging studies of normal, non-interacting spirals (e.g., Broeils & van Woerden 1994, and references therein). We have also noted other points of interest, like the presence of active nuclei.

4.1.1 Interacting group sample

NGC 2798/9 pair: our Nançay profile, like all other published single-dish profiles of the pair, is undoubtedly confused by H I emission from nearby spiral UGC 4904. VLA H I observations (Nordgren et al. 1997; see Table 6) show an integrated line flux of 7.0 Jy km s^-1 and a mean velocity of about 1800 km s^-1 for the pair, and 6.0 Jy km s^-1 centered on 1670 km s^-1 for UGC 4904. The pair shows an H I tail and signs of interaction in the velocity field; a total flux of about 5.0 Jy km s^-1 resides in the two disks, and about 2.0 Jy km s^-1 outside them.

NGC 3162: Four of the six available integrated line fluxes of this object are in agreement ( $\sim$ 26 Jy km s^-1), the exceptions being the considerably higher Nançay value (44.1 Jy km s^-1) of Bottinelli et al. (1982) and the considerably lower (6.2 Jy km s^-1) Arecibo value of Williams & Rood (1987), whose W₂₀ of 605 km s^-1 is about three times larger than the other available values.

NGC 3177: The 2 Nançay and the 3 Arecibo $I_{\rm HI}$ measurements are about equally divided around two values (5.9 and 3.3 Jy km s^-1) without consistency per telescope. This excludes a possible beam size effect and, in any case, the H I diameter of this galaxy with its $1'\,\hspace{-1.7mm}.\hspace{.0mm}5$ D₂₅ diameter is not expected to exceed the beam size of either telescope.

NGC 3185/87/89/93 subgroup: the area covering NGC 3185/87/89/93 was mapped in H I at the VLA by Williams et al. (1991), who, erroneously, refer to NGC 3189 as NGC 3190. These data show that our NGC 3185 spectrum will be confused by emission from NGC 3187 in the $\sim$ 1300-1400 km s^-1 range, and that our NGC 3187 and NGC 3189 spectra will be confused by each other in the $\sim$ 1400-1500 km s^-1 range. The Nançay pointings should cover essentially all emission from NGC 3187 and 3189, judging from the VLA H I column density map. The H I line flux we measured towards NGC 3187 (8.8 Jy km s^-1) is comparable to the value of 10.6 Jy km s^-1 measured at the VLA for this object, though on average two times lower than the previously published Nançay values (24.6: and 14.2 from, respectively, Bottinelli et al. 1982; Balkowski & Chamaraux 1983). The uncertain integrated H I line flux of NGC 3189 measured at Green Bank (7.3: Jy km s^-1, Huchtmeier 1982) and the Arecibo measurement of 6.1 by Krumm & Salpeter (1982) are about twice as large as our Nançay value (3.1). Our value is consistent, however, with the mean of the four other literature values, 3.5 Jy km s^-1. NGC 3185 is an (R)SB(r)a with a Seyfert2 spectrum, and NGC 3189 an SA(s)apec with a LINER spectrum.

NGC 3226/7 pair: mapped in H I at the VLA (Mundell et al. 1995). No H I was detected in NGC 3226, and NGC 3227 shows a complex H I distribution and kinematics. About half the H I resides in a disk with a normal rotation curve, the rest in two plumes extending 7' N and 16' S of the system, and in an H I feature at the base of the N plume which may be a gas-rich dwarf galaxy. As the plumes have a N-S orientation, the Nançay beam will cover almost all of the H I emission, as the southernmost half of the southern plume is relatively faint compared to the bulk of the emission. Our Nançay integrated line flux (16.6 Jy km s^-1) is consistent with the Green Bank and Jodrell Bank data, while the Arecibo values are a bit lower. The only significantly discrepant Arecibo value is the 6.8 Jy km s^-1from Chamaraux et al. (1987). Our W₂₀ profile width is consistent with the other measurements, but our W₅₀ value (103 km s^-1) is similar to the Green Bank measurement by Peterson (1979) only, the 5 other published values are $\sim$ 350 km s^-1 on average. NGC 3226 is an E2:pec with a LINER spectrum, and NGC 3227 an SAB(s)pec with a Seyfert1.5 spectrum.

Table 4: Nançay H I line data for the interacting group sample.
GH Ident. RA Dec. $V_{\rm HI}$ $I_{\rm HI}$ W₅₀ W₂₀ rms ${M}_{\rm HI}$ L_B ${M}_{\rm HI}$ /L_B

[log] [log]

No. No. (2000.0) kms^-1 Jy kms^-1 kms^-1 kms^-1 mJy ${M}_\odot$ $L_{\odot,B}$ ${M}_\odot$ / $L_{\odot,B}$

45 N2798/9* 09 17 27 41 59 50 $1750\pm8$ 10.9 304 424 2.7 9.18 9.90 0.19

N2844 09 21 48 40 09 07 $1494\pm4$ 7.6 309 337 2.8 9.03 9.48 0.35

N2852 09 23 14 40 09 53 $1781\pm3$ 5.2 211 232 2.1 8.86 9.37 0.31

58 N3162 10 13 32 22 44 23 $1301\pm2$ 25.6 183 204 5.9 9.27 9.80 0.30

N3177 10 16 35 21 07 29 $1326\pm16$ 3.4 180 325 3.3 8.39 9.48 0.08

N3185 10 17 39 21 41 19 $1225\pm6$ 3.1 248 276 2.5 8.35 9.55 0.06

N3187 10 17 48 21 52 25 $1589\pm11$ 8.8 236 296 5.5 8.81 9.19 0.41

N3189 10 18 06 21 49 53 $1300\pm23$ 5.0 458 560 4.4 8.56 9.94 0.04

N3193 10 18 25 21 53 42 $1361\pm25$ 1.5 470 514 2.2 8.05 10.00 0.01

N3213 10 21 18 19 39 07 $1345\pm13$ 1.3 149 187 2.4 7.97 9.03 0.09

N3226/7* 10 23 30 19 52 51 $1146\pm5$ 16.6 103 437 2.3 9.08 10.31 0.06

N3239 10 25 06 17 09 35 $762\pm1$ 43.3 132 183 3.5 9.50 10.00 0.32

67 U5870 10 45 59 34 57 53 $1992\pm4$ 4.6 229 244 2.9 8.80 9.25 0.35

N3381 10 48 25 34 42 44 $1629\pm2$ 13.0 68 135 3.5 9.25 9.85 0.25

N3395/6* 10 49 53 32 59 06 $1637\pm2$ 18.1 105 180 2.6 9.40 10.29 0.13

N3424 10 51 47 32 54 02 $1507\pm5$ 15.5 318 401 2.8 9.33 9.73 0.40

N3430 10 52 11 32 57 09 $1584\pm2$ 30.7 333 353 3.9 9.63 10.07 0.36

N3442 10 53 08 33 54 36 $1731\pm5$ 3.2 133 160 2.1 8.64 9.44 0.16

U6070 10 59 47 33 23 32 $1853\pm5$ 5.2 115 157 2.9 8.85 9.58 0.19

86 U6545 11 33 45 32 38 04 2630 1.0 150: 2.5 8.53 9.55 0.10

N3786/8* 11 39 43 31 55 16 $2674\pm7$ 14.1 436 535 2.3 9.57 10.28 0.19

92 N3902 11 49 19 26 07 22 $3651\pm11$ 8.9 241 371 4.5 9.85 10.22 0.43

N3920 11 50 06 24 55 15 $3635\pm3$ 8.4 181 211 2.9 9.82 10.12 0.51

U6806 11 50 20 25 57 42 $3751\pm2$ 17.5 205 245 2.8 10.14 10.05 1.24

N3944 11 53 06 26 12 28 -- <3.1 -- -- 3.4 <9.39 10.07 <0.21

I746 11 55 35 25 53 19 $5027\pm6$ 6.7 268 288 3.9 9.73 9.97 0.57

N3987 11 57 21 25 11 41 $4450\pm7$ 7.8 521 551 2.3 9.79 10.16 0.43

N3997 11 57 47 25 16 18 $4771\pm5$ 7.6 241 273 3.2 9.78 10.11 0.47

N4005 11 58 10 25 07 18 -- <2.3 -- -- 2.6 <9.27 10.16 <0.13

N4015A/B* 11 58 43 25 02 35 $4516\pm25$ 3.1 404 524 3.1 9.39 10.70 0.05

N4022 11 59 01 25 13 19 -- <2.6 -- -- 2.9 <9.34 10.02 <0.20

126 N5341 13 52 32 37 48 58 $3649\pm4$ 5.1 252 265 3.1 9.42 9.91 0.33

N5351 13 53 28 37 54 52 $3607\pm4$ 18.3 415 438 5.1 9.98 10.34 0.44

N5378 13 56 51 37 48 00 $3000\pm22$ 3.9 301 367 5.0 9.31 10.07 0.17

N5380 13 56 57 37 36 34 $3000\pm11$ 2.9 304 336 2.5 9.18 10.23 0.09

N5394/5* 13 58 36 37 26 25 $3454\pm12$ 20.0 457 577 5.4 10.02 10.78 0.17

141 N5529 14 15 34 36 13 36 $2884\pm3$ 26.4 565 604 3.1 10.17 10.49 0.48

N5533 14 16 08 35 20 42 $3864\pm2$ 19.3 431 456 2.7 10.04 10.49 0.35

N5544/5* 14 17 04 36 34 28 $3071\pm14$ 3.8 247 310 2.9 9.33 10.14 0.16

N5557 14 18 26 36 29 38 -- <2.6 -- -- 2.9 <9.17 10.81 <0.02

N5589 14 21 25 35 16 15 $3397\pm8$ 1.3 182 195 2.2 <8.20 9.89 0.10

N5590 14 21 38 35 12 19 -- <2.8 -- -- 3.1 <8.96 10.21 <0.10

N5596 14 22 29 37 07 17 $3122\pm13$ 1.0 544 554 3.4 8.75 9.81 0.09

N5614 14 24 08 34 51 27 $3893\pm12$ 3.2 138 246 2.3 9.26 10.56 0.05

N5656 14 30 25 35 19 12 $3163\pm6$ 8.2 338 377 3.2 9.67 10.52 0.14

N5675 14 32 40 36 18 12 -- <2.2 -- -- 2.4 <9.09 10.09 <0.10

N5684 14 35 50 36 32 35 -- <2.3 -- -- 2.6 <9.12 10.14 <0.10

N5695 14 37 23 36 34 15 -- <2.4 -- -- 2.7 <9.13 10.14 <0.10

153 N5929/30* 15 26 07 41 40 28 $2539\pm14$ 3.0 219 299 2.3 8.96 10.13 0.07

U9858 15 26 41 40 33 52 $2621\pm2$ 30.5 364 388 2.6 10.00 9.80 1.57

156 N5951 15 33 43 15 00 27 $1780\pm1$ 17.5 265 284 1.6 9.48 9.67 0.65

N5953/4* 15 34 33 15 11 57 $1966\pm4$ 7.7 146 275 1.9 9.13 9.81 0.21

N5962 15 36 32 16 36 32 $1957\pm2$ 17.6 341 364 2.3 9.49 10.25 0.17

**Table 4:** Nançay H I line data for the interacting group sample.
GH	Ident.	RA	Dec.	$V_{\rm HI}$	$I_{\rm HI}$	W₅₀	W₂₀	rms	${M}_{\rm HI}$	L_B	${M}_{\rm HI}$ /L_B
									[log]	[log]
No.	No.	(2000.0)	kms^-1	Jy kms^-1	kms^-1	kms^-1	mJy	${M}_\odot$	$L_{\odot,B}$	${M}_\odot$ / $L_{\odot,B}$

45	N2798/9*	09 17 27	41 59 50	$1750\pm8$	10.9	304	424	2.7	9.18	9.90	0.19
	N2844	09 21 48	40 09 07	$1494\pm4$	7.6	309	337	2.8	9.03	9.48	0.35
	N2852	09 23 14	40 09 53	$1781\pm3$	5.2	211	232	2.1	8.86	9.37	0.31

58	N3162	10 13 32	22 44 23	$1301\pm2$	25.6	183	204	5.9	9.27	9.80	0.30
	N3177	10 16 35	21 07 29	$1326\pm16$	3.4	180	325	3.3	8.39	9.48	0.08
	N3185	10 17 39	21 41 19	$1225\pm6$	3.1	248	276	2.5	8.35	9.55	0.06
	N3187	10 17 48	21 52 25	$1589\pm11$	8.8	236	296	5.5	8.81	9.19	0.41
	N3189	10 18 06	21 49 53	$1300\pm23$	5.0	458	560	4.4	8.56	9.94	0.04
	N3193	10 18 25	21 53 42	$1361\pm25$	1.5	470	514	2.2	8.05	10.00	0.01
	N3213	10 21 18	19 39 07	$1345\pm13$	1.3	149	187	2.4	7.97	9.03	0.09
	N3226/7*	10 23 30	19 52 51	$1146\pm5$	16.6	103	437	2.3	9.08	10.31	0.06
	N3239	10 25 06	17 09 35	$762\pm1$	43.3	132	183	3.5	9.50	10.00	0.32

67	U5870	10 45 59	34 57 53	$1992\pm4$	4.6	229	244	2.9	8.80	9.25	0.35
	N3381	10 48 25	34 42 44	$1629\pm2$	13.0	68	135	3.5	9.25	9.85	0.25
	N3395/6*	10 49 53	32 59 06	$1637\pm2$	18.1	105	180	2.6	9.40	10.29	0.13
	N3424	10 51 47	32 54 02	$1507\pm5$	15.5	318	401	2.8	9.33	9.73	0.40
	N3430	10 52 11	32 57 09	$1584\pm2$	30.7	333	353	3.9	9.63	10.07	0.36
	N3442	10 53 08	33 54 36	$1731\pm5$	3.2	133	160	2.1	8.64	9.44	0.16
	U6070	10 59 47	33 23 32	$1853\pm5$	5.2	115	157	2.9	8.85	9.58	0.19

86	U6545	11 33 45	32 38 04	2630	1.0	150:		2.5	8.53	9.55	0.10
	N3786/8*	11 39 43	31 55 16	$2674\pm7$	14.1	436	535	2.3	9.57	10.28	0.19

92	N3902	11 49 19	26 07 22	$3651\pm11$	8.9	241	371	4.5	9.85	10.22	0.43
	N3920	11 50 06	24 55 15	$3635\pm3$	8.4	181	211	2.9	9.82	10.12	0.51
	U6806	11 50 20	25 57 42	$3751\pm2$	17.5	205	245	2.8	10.14	10.05	1.24
	N3944	11 53 06	26 12 28	--	<3.1	--	--	3.4	<9.39	10.07	<0.21
	I746	11 55 35	25 53 19	$5027\pm6$	6.7	268	288	3.9	9.73	9.97	0.57
	N3987	11 57 21	25 11 41	$4450\pm7$	7.8	521	551	2.3	9.79	10.16	0.43
	N3997	11 57 47	25 16 18	$4771\pm5$	7.6	241	273	3.2	9.78	10.11	0.47
	N4005	11 58 10	25 07 18	--	<2.3	--	--	2.6	<9.27	10.16	<0.13
	N4015A/B*	11 58 43	25 02 35	$4516\pm25$	3.1	404	524	3.1	9.39	10.70	0.05
	N4022	11 59 01	25 13 19	--	<2.6	--	--	2.9	<9.34	10.02	<0.20

126	N5341	13 52 32	37 48 58	$3649\pm4$	5.1	252	265	3.1	9.42	9.91	0.33
	N5351	13 53 28	37 54 52	$3607\pm4$	18.3	415	438	5.1	9.98	10.34	0.44
	N5378	13 56 51	37 48 00	$3000\pm22$	3.9	301	367	5.0	9.31	10.07	0.17
	N5380	13 56 57	37 36 34	$3000\pm11$	2.9	304	336	2.5	9.18	10.23	0.09
	N5394/5*	13 58 36	37 26 25	$3454\pm12$	20.0	457	577	5.4	10.02	10.78	0.17

141	N5529	14 15 34	36 13 36	$2884\pm3$	26.4	565	604	3.1	10.17	10.49	0.48
	N5533	14 16 08	35 20 42	$3864\pm2$	19.3	431	456	2.7	10.04	10.49	0.35
	N5544/5*	14 17 04	36 34 28	$3071\pm14$	3.8	247	310	2.9	9.33	10.14	0.16
	N5557	14 18 26	36 29 38	--	<2.6	--	--	2.9	<9.17	10.81	<0.02
	N5589	14 21 25	35 16 15	$3397\pm8$	1.3	182	195	2.2	<8.20	9.89	0.10
	N5590	14 21 38	35 12 19	--	<2.8	--	--	3.1	<8.96	10.21	<0.10
	N5596	14 22 29	37 07 17	$3122\pm13$	1.0	544	554	3.4	8.75	9.81	0.09
	N5614	14 24 08	34 51 27	$3893\pm12$	3.2	138	246	2.3	9.26	10.56	0.05
	N5656	14 30 25	35 19 12	$3163\pm6$	8.2	338	377	3.2	9.67	10.52	0.14
	N5675	14 32 40	36 18 12	--	<2.2	--	--	2.4	<9.09	10.09	<0.10
	N5684	14 35 50	36 32 35	--	<2.3	--	--	2.6	<9.12	10.14	<0.10
	N5695	14 37 23	36 34 15	--	<2.4	--	--	2.7	<9.13	10.14	<0.10

153	N5929/30*	15 26 07	41 40 28	$2539\pm14$	3.0	219	299	2.3	8.96	10.13	0.07
	U9858	15 26 41	40 33 52	$2621\pm2$	30.5	364	388	2.6	10.00	9.80	1.57

156	N5951	15 33 43	15 00 27	$1780\pm1$	17.5	265	284	1.6	9.48	9.67	0.65
	N5953/4*	15 34 33	15 11 57	$1966\pm4$	7.7	146	275	1.9	9.13	9.81	0.21
	N5962	15 36 32	16 36 32	$1957\pm2$	17.6	341	364	2.3	9.49	10.25	0.17

NGC 3239: Four small galaxies will be included in the Nançay beam centered on this nearby (V=830 km s^-1) irregular galaxy. Three of these have been previously catalogued, two (CGCG 094-039 and CGCG 094-043) with optical redshifts (Falco et al. 1999) around 13,300 km s^-1, and another, CGCG 094-040, without known redshift. The latter, faint ( $B\rm _T$ 15.3 mag) object of less than 1' diameter, is not expected to cause confusion with the very strong (75 Jy km s^-1) H I detection of NGC 3239. The nearby companions may well explain the much higher H I line flux measured at Green Bank ( $\sim$ 80 Jy km s^-1 on average), compared to the Nançay and Arecibo values (43-61 Jy km s^-1) - see Table 6. In principle, some H I emission from NGC 3239 may fall outside the Nançay beam, as its optical E-W D₂₅ diameter of $4'\,\hspace{-1.7mm}.\hspace{.0mm}5$ exceeds the $3'\,\hspace{-1.7mm}.\hspace{.0mm}6$ E-W HPBW, and as it looks like the result of a recent merger, which might have H I plumes associated with it, not covered by the Nançay beam.

UGC 5870: we registered an off-band detection of a galaxy at V=1616 km s^-1, with a ${\textit FWHM}=120$ km s^-1. This detection does not appear to disturb the detection of the target galaxy, which shows a classical double-horned spectrum.

NGC 3381: The integrated line flux of 21 Jy km s^-1 measured at Arecibo by Krumm & Salpeter (1980) is the result of a crude mapping of the galaxy's H I distribution; a lower limit of 10' is given by the authors for the H I diameter, indicating that the actual extent exceeds the mapped area. The other available $I_{\rm HI}$ values (8.5-13 Jy km s^-1) underestimate the total line flux. No galaxies that could be potential sources of confusion were found in a $24'\times24'$ area centered on the object.

NGC 3395/96: this pair was mapped in H I at the VLA (Clemens et al. 1999). An integrated flux of 22 Jy km s^-1was detected in the pair, which shows a clear H I bridge, as well as 4 Jy km s^-1 in an H I tail extending to a distance of 10' SW of the pair. The H I kinematics were modeled by the authors using N-body simulations, which indicate that the tail was stripped from NGC 3395. The Nançay and Arecibo line fluxes agree well, and are about two times smaller than the 38.4 Jy km s^-1was at Green Bank by Shostak (1975).

NGC 3424 and NGC 3430: our Nançay profiles of these two nearby objects ( $4'\,\hspace{-1.7mm}.\hspace{.0mm}5$ E-W separation) will be mutually confused by their line emission, as will the published Green Bank and Jodrell Bank profiles of NGC 3430. The Arecibo profiles (Helou et al. 1982) of the two galaxies are not expected to be confused, given the telescope's small HPBW. The Arecibo central velocities are 1501/1586 km s^-1, the FWHMs 353/340 km s^-1, and the integrated line fluxes 14.0/44.1 Jy km s^-1, respectively.

NGC 3442: our Nançay profile parameters agree well with those of 4 of the 5 available Arecibo profiles; the integrated line flux measured at Arecibo by Magri (1994) is about 3 times larger (9.1 Jy km s^-1), though the profile's central velocity and linewidth are consistent the other measurements.

Group GH86: UGC 6545: for this object two completely discrepant optical redshifts have been published: $2619\pm41$ km s^-1, a CfA redshift value (Huchra et al. 1983; Huchra et al. 1995) and $6419\pm90$ km s^-1 (Karachentsev 1980). Our Nançay value, 2630 km s^-1, is consistent with the Huchra et al. value.

NGC 3786/8: short Westerbork synthesis observations of the pair were obtained by Oosterloo & Shostak (1993), but they refrain from listing global line parameters as NGC 3786 (= UGC 6621) is "not detected or confused with NGC 3788 (= UGC 6623)'', and NGC 3788 is "possibly confused with NGC 3786''. Their Arecibo observations of the pair were confused as well and no single-dish profile parameters are given. Our Nançay integrated line flux (14.1 Jy km s^-1) is similar to the Green Bank value, and both are about 1.5 times larger than 4 of the 5 available Arecibo values, the exception being the much lower (4.9 Jy km s^-1) measurement by Lewis et al. (1985). NGC 3786 is an SAB(rs)apec with a Seyfert1.8 spectrum.

UGC 6806: our Nançay profile will be confused by nearby UGC 6807, a $B\rm _T$ 15.0 mag Irregular at 2' separation. Even the Arecibo profile of UGC 6806 (Williams 1986, see Table 6) should be confused, as their HPBW is about the same as the galaxies' separation. The Nançay integrated line flux (17.5 Jy km s^-1) is 4 times higher than the Arecibo value, though the central velocities and profile widths are quite similar. For UGC 6807, only a Nançay profile pointed at UGC 6807 is available in the literature (Garcia et al. 1994), which will be confused by UGC 6806. In conclusion, no reliable H I profiles of these two objects are available.

NGC 3944: E/S0 galaxy, not detected in our survey (estimated $I_{\rm HI}<\, 3.1$ Jy km s^-1, ${M}_{\rm HI}$ /L_B $\,<\,0.21$ ${M}_\odot$ / $L_{\odot,B}$ ).

NGC 3987: Our H I velocity is about 50 km s^-1 lower than the 4 reported Arecibo values, and all profiles have very large widths. The mean values for the Arecibo spectra of NGC 3987 are $V_{\rm HI}=4500$ km s^-1, W₂₀=569 km s^-1 and $I_{\rm HI}=7.1$ Jy km s^-1. A possible source of confusion is the $B\rm _T$ 15.8 mag Sbc spiral NGC 3989, at an E-W distance of $1'\,\hspace{-1.7mm}.\hspace{.0mm}2$ from NGC 3987. NGC 3989 has no published optical redshift. The Arecibo H I profile parameters for NGC 3989 of Mould et al. (1993) and Scodeggio et al. (1993 - where NGC 3987 is referred to as NGC 3997) are comparable (average $V_{\rm HI}=4623$ km s^-1, W₂₀=519 km s^-1 and $I_{\rm HI}=3.2$ Jy km s^-1), while the Arecibo profile of Williams (1986) has a 90 km s^-1 higher central velocity (4713 km s^-1), less flux (2.0 Jy km s^-1) and a considerably smaller width ( W₂₀=374 km s^-1). Confusion between the Arecibo profiles of NGC 3987 and 3989 is in principle possible, as their projected separation is $2'\,\hspace{-1.7mm}.\hspace{.0mm}6$ ; in fact, the spectrum of Scodeggio et al. has a complex structure, indicative of confusion or interaction. On the other hand, the H I emission observed at Arecibo towards NGC 3989 cannot explain the H I observed at Nançay towards NGC 3987 below the low-velocity edge of the Arecibo profile of NGC 3987. In conclusion, the H I distribution appears complex and extended tidal debris may be present in H I.

NGC 3997: our Nançay profile ( $V_{\rm HI}= 4771$ km s^-1, W₂₀=241 km s^-1, $I_{\rm HI}=7.6$ Jy km s^-1) can in principle be confused by two galaxies: NGC 3993, a $B_{\rm T}$ 14.2 mag Sbc spiral with $V_{\rm opt}=4824\pm58$ km s^-1 (LEDA) $2'\,\hspace{-1.7mm}.\hspace{.0mm}3$ west of NGC 3997 and NGC 4000, a $B_{\rm T}$ 15.2 mag Sbc spiral without known $V_{\rm opt}$ , $1'\,\hspace{-1.7mm}.\hspace{.0mm}9$ east of NGC 3997. Arecibo observations with a HPBW of $3'\,\hspace{-1.7mm}.\hspace{.0mm}3$ are available of all three galaxies. These will certainly resolve the confusion between NGC 3997 and NGC 4000 ( $7'\,\hspace{-1.7mm}.\hspace{.0mm}9$ separation) and in principle between NGC 3997 and NGC 3993 ( $2'\,\hspace{-1.7mm}.\hspace{.0mm}8$ separation) as well. Measured at Arecibo, the H I profile parameters of NGC 3997 are V=4768 km s^-1, W₂₀=289 km s^-1, $I_{\rm HI}=7.9$ Jy km s^-1 (Gavazzi 1987; Williams 1986), those of NGC 3993 are V=4826 km s^-1, W₂₀=382 km s^-1, $I_{\rm HI}=4.3$ Jy km s^-1 (Dell'Antonio et al. 1996; Williams 1986), and those of NGC 4000 are V=4556 km s^-1, W₂₀=310 km s^-1, $I_{\rm HI}=2.3$ Jy km s^-1 (Gavazzi 1987; Williams 1986).

NGC 4005: Sb spiral, not detected clearly in our survey (estimated $I_{\rm HI}<2.3$ Jy km s^-1). The 3 published Arecibo detections have almost the same integrated line flux as our estimated 3 $\sigma$ upper limit ( $\sim$ 1.8 Jy km s^-1).

NGC 4015A/B: very close pair, with only $0'\,\hspace{-1.7mm}.\hspace{.0mm}4$ separation between the nuclei; NGC 4015 is seen face-on, while NGC 4015 B is seen edge-on. Their optical redshifts are $4780\pm57$ and $4347\pm44$ km s^-1, respectively. Both the Arecibo and the Effelsberg spectra (Williams 1986; Huchtmeier et al. 1995) show two distinct peaks, centered on $\sim$ 4100 and $\sim$ 4500 km s^-1, respectively. In both papers the global line parameters listed refer to the entire emission line profile, resulting in very large W₂₀ linewidths of 700-815 km s^-1. In our spectrum, only the emission centered on 4500 km s^-1 is present. Huchtmeier et al. considered their profile confused by nearby spirals, but there are no candidates for confusion in the Arecibo or Nançay beams. The origin of the H I emission at 4100 km s^-1 is unclear, but could be related to tidal debris.

NGC 4022: S0 galaxy, not detected in our survey (estimated $I_{\rm HI}\,<\,2.6$ Jy km s^-1, ${M}_{\rm HI}$ /L_B $\,<\,$ 0.20 ${M}_\odot$ / $L_{\odot,B}$ ).

NGC 5351: short Westerbork H I synthesis observations (Rhee & van Albada 1996) show an H I diameter of $4'\,\hspace{-1.7mm}.\hspace{.0mm}0$ at a surface density level of 1 ${M}_\odot$ pc^-2, 1.4 times the optical D₂₅ diameter. Though the H I major axis diameter somewhat exceeds the Nançay $3'\,\hspace{-1.7mm}.\hspace{.0mm}6$ E-W HPBW, all measured integrated line fluxes are in agreement and no significant flux seems to have been missed in our survey.

NGC 5378 and 5380: in principle, our Nançay profiles of these two galaxies are expected to be mutually confused, as they are separated by $11'\,\hspace{-1.7mm}.\hspace{.0mm}4$ (about half a HPBW) in the N-S direction. As NGC 5380 has been classified as an elliptical/S0 in various catalogues, we do not expect to detect it in H I; an upper limit of 1.26 Jy km s^-1was reported for NGC 5380 at Arecibo (Chamaraux et al. 1987), where the $3'\,\hspace{-1.7mm}.\hspace{.0mm}6$ HPBW should not cause any confusion with NGC 5378. In fact, our detections towards the centres of both objects show strikingly similar profile parameters, indicating they are in fact both detections of the spiral NGC 5378. For their Nançay profile, Theureau et al. (1998), who assumed it to be confused with NGC 5380, listed only a central velocity (2715 km s^-1), which is about 260 km s^-1 lower than that of the other two spectra. However, our measurement of the central H I velocity from the spectrum of Theureau et al. is 2990 km s^-1, in agreement with the other two spectra, and the linewidths we measured from their spectrum (see Table 6) are in agreement with our Nançay values. The integrated line flux we estimated from the plotted spectrum, $\sim$ 3.9 Jy km s^-1, is in also agreement with our value. Therefore, only the values measured by us from the Theureau et al. spectrum have been listed in Table 6. On the other hand, the line flux of NGC 5378 measured at Green Bank by Richter & Huchtmeier (1991), 11.2 Jy km s^-1, is much higher than the Nançay values and their profile widths about 40% larger. This Green Bank profile is not expected to be confused by NGC 5380, given the telescope's HPBW, nor are any other galaxies visible in its vicinity. A broad RFI signal seems the only plausible cause of the striking discrepancy between the Green Bank and Nançay profiles.

NGC 5529: short Westerbork H I synthesis observations (Rhee & van Albada 1996) show an H I diameter of $6'\,\hspace{-1.7mm}.\hspace{.0mm}6$ at a surface density level of 1 ${M}_\odot$ pc^-2, the same as its optical D₂₅ diameter. Their position-velocity map indicates that the Nançay beam with its $3'\,\hspace{-1.7mm}.\hspace{.0mm}6$ E-W HPBW does not cover all of the H I emission of this edge-on E-W oriented spiral. In fact, our line flux value of 26.4 Jy km s^-1 is significantly lower than the 36.3 Jy km s^-1 measured at Westerbork, while the latter is in agreement with $\sim$ 40 Jy km s^-1 measured at Green Bank and Jodrell Bank, whose beams should cover the entire H I disk.

NGC 5533: short Westerbork H I synthesis observations (Broeils & van Woerden 1994) show that its radial H I distribution is symmetric and that it extends out to 2.4 times the optical D₂₅ diameter of the galaxy ( $3'\,\hspace{-1.7mm}.\hspace{.0mm}2$ ), measured at a surface density level of 1 ${M}_\odot$ pc^-2. The integrated line flux measured at Westerbork (35.3 Jy km s^-1) is much larger than the Nançay and Green Bank single dish fluxes (19 and 12 Jy km s^-1, respectively), and the Arecibo flux (8 Jy km s^-1) is even smaller. The linewidths of the Westerbork and single-dish profiles are comparable, however. The discrepancy between the Westerbork and Green Bank line fluxes is puzzling, as the Green Bank $10'\,\hspace{-1.7mm}.\hspace{.0mm}7$ HPBW should cover the bulk of the H I emission, seen the $7'\,\hspace{-1.7mm}.\hspace{.0mm}7$ H I disk major axis measured at Westerbork.

NGC 5544/5: Very close interacting pair, the nuclei are separated by only $0'\,\hspace{-1.7mm}.\hspace{.0mm}6$ . Our Nançay values are in agreement with the 7 published Arecibo, Effelsberg and Green Bank profiles, while the Nançay values of Bottinelli et al. (1982) show a considerably higher line flux and linewidths.

NGC 5557: not detected in our survey (estimated $I_{\rm HI}<2.6$ Jy km s^-1). Classified as an elliptical; the upper limit to its gas content ( ${M}_{\rm HI}$ /L_B $\,<\,$ 0.02 ${M}_\odot$ / $L_{\odot,B}$ ) is consistent with its classification.

Table 5: Nançay H I line data for the control group sample.
GH Ident. RA Dec. $V_{\rm HI}$ $I_{\rm HI}$ W₅₀ W₂₀ rms ${M}_{\rm HI}$ L_B ${M}_{\rm HI}$ /L_B

[log] [log]

No. No. (2000.0) kms^-1 Jy kms^-1 kms^-1 kms^-1 mJy ${M}_\odot$ $L_{\odot,B}$ ${M}_\odot$ / $L_{\odot,B}$

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

49 N2998 09 48 44 44 04 52 $4778\pm5$ 17.5 371 465 3.6 10.24 10.58 0.46

N3009 09 50 11 44 17 40 -- <2.4 -- -- 2.7 <9.38 10.48 <0.08

U5295 09 52 54 42 50 55 $4787\pm2$ 16.8 279 303 3.1 10.23 10.12 1.28

57 N3156 10 12 41 03 07 50 -- <2.6 -- -- 2.9 <8.24 9.40 <0.07

N3165 10 13 31 03 22 32 $1329\pm7$ 5.9 153 225 2.9 8.58 8.84 0.55

N3166 10 13 45 03 25 31 $1356\pm8$ 12.0 66 218 5.9 8.89 10.14 0.06

N3169 10 14 14 03 28 08 $1238\pm4$ 59.2 363 479 5.8 9.58 10.22 0.23

89 U6617 11 39 17 09 57 22 -- <2.0 -- -- 2.3 <9.50 10.30 <0.16

N3817 11 41 53 10 18 07 6106: 2.1 270: 2.9 9.61 10.31 0.16

N3822/5* 11 42 18 10 16 16 -- <2.5 -- -- 2.7 <9.58 10.71 <0.08

I724 11 43 35 08 56 31 $5966\pm6$ 2.6 497 508 2.3 9.61 10.62 0.10

N3839 11 43 54 10 46 59 $5903\pm13$ 8.7 301 338 3.8 10.21 10.57 0.44

N3843 11 43 54 07 55 32 -- <2.1 -- -- 2.4 <9.53 10.41 <0.13

118 N5141 13 24 52 36 22 40 -- <2.3 -- -- 2.5 <9.46 10.41 <0.11

N5142 13 25 01 36 23 58 -- <2.2 -- -- 2.4 <9.97 10.25 <0.16

N5149 13 26 10 35 56 04 $5652\pm7$ 4.7 381 407 3.1 9.78 10.37 0.26

123 N5289 13 45 09 41 30 09 $2526\pm4$ 9.4 357 379 3.8 9.42 9.69 0.54

N5290 13 45 19 41 42 55 $2573\pm6$ 11.7 461 477 4.5 9.52 9.95 0.37

N5297 13 46 24 43 52 25 $2409\pm2$ 43.7 391 418 5.9 10.09 10.31 0.60

N5311 13 48 56 39 59 07 -- <2.4 -- -- 2.6 <8.83 9.83 <0.10

U8736 13 49 04 39 29 56 $2384\pm13$ 2.8 245 286 3.5 8.90 9.57 0.21

N5313 13 49 45 39 59 10 $2562\pm29$ 6.9 409 520 6.9 9.29 10.19 0.13

N5320 13 50 21 41 22 06 $2619\pm2$ 19.5 297 315 4.8 9.74 10.09 0.45

N5326 13 50 51 39 34 29 $2513\pm36$ 1.0 387 469 2.5 8.45 10.11 0.02

N5336 13 52 11 43 14 34 $2336\pm4$ 7.7 186 227 3.0 9.34 9.84 0.25

N5337 13 52 23 39 41 15 $2165\pm17$ 2.9 397 435 3.5 8.91 9.93 0.10

N5350/4* 13 53 24 40 20 00 $2321\pm3$ 23.9 292 316 6.9 9.83 10.65 0.15

N5353 13 53 27 40 17 03 $2325\pm3$ 18.3 291 311 5.0 9.71 10.48 0.17

N5355 13 53 46 40 20 17 $2342\pm24$ 2.6 259 315: 5.7 8.86 9.68 0.15

N5362 13 54 54 41 18 51 $2178\pm4$ 7.9 258 275 3.8 9.35 9.99 0.23

N5371 13 55 41 40 27 44 $2558\pm3$ 24.4 391 409 5.5 9.84 10.72 0.13

N5383 13 57 05 41 50 44 $2270\pm3$ 18.0 292 328 4.2 9.70 10.43 0.19

155 N5934 15 28 12 42 55 49 $5701\pm23$ 3.5 131 382 2.8 9.72 10.15 0.37

N5945 15 29 45 42 55 14 $5523\pm6$ 4.3 348 362 2.3 9.80 10.47 0.13

I4562 15 35 58 43 29 40 -- <1.7 -- -- 1.8 <9.39 10.46 <0.08

I4564 15 36 27 43 31 08 $5981\pm14$ 3.8 433 516 2.4 9.75 10.22 0.34

I4566 15 36 43 43 32 24 $5774\pm15$ 1.6 236 275 2.3 9.38 10.34 0.11

I4567 15 37 13 43 17 54 $5738\pm6$ 6.5 300 337 2.3 9.98 10.58 0.25

**Table 5:** Nançay H I line data for the control group sample.
GH	Ident.	RA	Dec.	$V_{\rm HI}$	$I_{\rm HI}$	W₅₀	W₂₀	rms	${M}_{\rm HI}$	L_B	${M}_{\rm HI}$ /L_B
									[log]	[log]
No.	No.	(2000.0)	kms^-1	Jy kms^-1	kms^-1	kms^-1	mJy	${M}_\odot$	$L_{\odot,B}$	${M}_\odot$ / $L_{\odot,B}$
(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)	(11)

49	N2998	09 48 44	44 04 52	$4778\pm5$	17.5	371	465	3.6	10.24	10.58	0.46
	N3009	09 50 11	44 17 40	--	<2.4	--	--	2.7	<9.38	10.48	<0.08
	U5295	09 52 54	42 50 55	$4787\pm2$	16.8	279	303	3.1	10.23	10.12	1.28

57	N3156	10 12 41	03 07 50	--	<2.6	--	--	2.9	<8.24	9.40	<0.07
	N3165	10 13 31	03 22 32	$1329\pm7$	5.9	153	225	2.9	8.58	8.84	0.55
	N3166	10 13 45	03 25 31	$1356\pm8$	12.0	66	218	5.9	8.89	10.14	0.06
	N3169	10 14 14	03 28 08	$1238\pm4$	59.2	363	479	5.8	9.58	10.22	0.23

89	U6617	11 39 17	09 57 22	--	<2.0	--	--	2.3	<9.50	10.30	<0.16
	N3817	11 41 53	10 18 07	6106:	2.1	270:		2.9	9.61	10.31	0.16
	N3822/5*	11 42 18	10 16 16	--	<2.5	--	--	2.7	<9.58	10.71	<0.08
	I724	11 43 35	08 56 31	$5966\pm6$	2.6	497	508	2.3	9.61	10.62	0.10
	N3839	11 43 54	10 46 59	$5903\pm13$	8.7	301	338	3.8	10.21	10.57	0.44
	N3843	11 43 54	07 55 32	--	<2.1	--	--	2.4	<9.53	10.41	<0.13

118	N5141	13 24 52	36 22 40	--	<2.3	--	--	2.5	<9.46	10.41	<0.11
	N5142	13 25 01	36 23 58	--	<2.2	--	--	2.4	<9.97	10.25	<0.16
	N5149	13 26 10	35 56 04	$5652\pm7$	4.7	381	407	3.1	9.78	10.37	0.26

123	N5289	13 45 09	41 30 09	$2526\pm4$	9.4	357	379	3.8	9.42	9.69	0.54
	N5290	13 45 19	41 42 55	$2573\pm6$	11.7	461	477	4.5	9.52	9.95	0.37
	N5297	13 46 24	43 52 25	$2409\pm2$	43.7	391	418	5.9	10.09	10.31	0.60
	N5311	13 48 56	39 59 07	--	<2.4	--	--	2.6	<8.83	9.83	<0.10
	U8736	13 49 04	39 29 56	$2384\pm13$	2.8	245	286	3.5	8.90	9.57	0.21
	N5313	13 49 45	39 59 10	$2562\pm29$	6.9	409	520	6.9	9.29	10.19	0.13
	N5320	13 50 21	41 22 06	$2619\pm2$	19.5	297	315	4.8	9.74	10.09	0.45
	N5326	13 50 51	39 34 29	$2513\pm36$	1.0	387	469	2.5	8.45	10.11	0.02
	N5336	13 52 11	43 14 34	$2336\pm4$	7.7	186	227	3.0	9.34	9.84	0.25
	N5337	13 52 23	39 41 15	$2165\pm17$	2.9	397	435	3.5	8.91	9.93	0.10
	N5350/4*	13 53 24	40 20 00	$2321\pm3$	23.9	292	316	6.9	9.83	10.65	0.15
	N5353	13 53 27	40 17 03	$2325\pm3$	18.3	291	311	5.0	9.71	10.48	0.17
	N5355	13 53 46	40 20 17	$2342\pm24$	2.6	259	315:	5.7	8.86	9.68	0.15
	N5362	13 54 54	41 18 51	$2178\pm4$	7.9	258	275	3.8	9.35	9.99	0.23
	N5371	13 55 41	40 27 44	$2558\pm3$	24.4	391	409	5.5	9.84	10.72	0.13
	N5383	13 57 05	41 50 44	$2270\pm3$	18.0	292	328	4.2	9.70	10.43	0.19

155	N5934	15 28 12	42 55 49	$5701\pm23$	3.5	131	382	2.8	9.72	10.15	0.37
	N5945	15 29 45	42 55 14	$5523\pm6$	4.3	348	362	2.3	9.80	10.47	0.13
	I4562	15 35 58	43 29 40	--	<1.7	--	--	1.8	<9.39	10.46	<0.08
	I4564	15 36 27	43 31 08	$5981\pm14$	3.8	433	516	2.4	9.75	10.22	0.34
	I4566	15 36 43	43 32 24	$5774\pm15$	1.6	236	275	2.3	9.38	10.34	0.11
	I4567	15 37 13	43 17 54	$5738\pm6$	6.5	300	337	2.3	9.98	10.58	0.25

Note: $I_{\rm HI}$ : upper limits are 3 $\sigma$ for 300 kms^-1 wide, flat-topped profiles; ":'' denotes an uncertain value.

NGC 5589: Though our H I velocity and linewidths are comparable to the Arecibo values listed in the Huchtmeier & Richter (1989) catalogue, our integrated line flux of 1.5 Jy km s^-1 is considerable higher than the uncertain $0.53\,\pm\,0.36$ Jy km s^-1 listed as the Arecibo value. However, this Arecibo reference, referred to as "Richter & Williams 1989, to be submitted'' in the Huchtmeier & Richter catalogue, has apparently never appeared in print. No confusion is expected at Nançay from the S0 galaxy NGC 5590 (see below), which lies at an E-W separation of $2'\,\hspace{-1.7mm}.\hspace{.0mm}8$ from NGC 5589.

NGC 5590: not detected in our survey (estimated $I_{\rm HI}<2.8$ Jy km s^-1). Classified as a lenticular; the upper limit to its gas content ( ${M}_{\rm HI}$ /L_B $\,<\,$ 0.10 ${M}_\odot$ / $L_{\odot,B}$ ) is consistent with its classification.

NGC 5614 (= Arp 178): Four of the 5 published H I velocities agree, except for the $\sim$ 43 km s^-1 higher Green Bank value by Richter & Huchtmeier (1991). Our W₅₀ linewidth of 138 km s^-1 is comparable to the Arecibo value listed in Huchtmeier & Richter (1989) but much smaller than the Green Bank and Nançay literature values of 220-250 km s^-1, though our W₅₀ value of 246 km s^-1 is comparable to the published values.

NGC 5656: our Nançay values agree with the published Nançay values (Theureau et al. 1998), if we multiply their integrated line flux (6.1 Jy km s^-1) by a factor of 1.26 to convert their flux calibration to the one we adopted (see Matthews et al. 2000, and references therein) and with the Arecibo measurement of 7.9 Jy km s^-1 listed in Huchtmeier & Richter (1989); surprisingly, the galaxy was not detected ( $I_{\rm HI}\leq3.0$ Jy km s^-1) at Arecibo by Krumm & Salpeter (1980).

NGC 5675: this SBb spiral with a LINER spectrum was not detected in our Nançay survey (estimated $I_{\rm HI}<2.2$ Jy km s^-1), nor at Arecibo (see Table 7). The best upper limit on its ${M}_{\rm HI}$ /L_B ratio, 0.10 ${M}_\odot$ / $L_{\odot,B}$ , is quite low for its type.

NGC 5695: this SBb with a Seyfert2 spectrum was not clearly detected in our Nançay survey (estimated $I_{\rm HI}<2.4$ Jy km s^-1), which is consistent with Arecibo detections. The upper limit on its ${M}_{\rm HI}$ /L_B ratio, 0.10 ${M}_\odot$ / $L_{\odot,B}$ , is low for its classification.

NGC 5929/30 (= Arp 90): very close pair ( $0'\,\hspace{-1.7mm}.\hspace{.0mm}5$ separation), well within the Nançay beam and clearly detected. NGC 5929 is a $B\rm _T$ 14.1 mag Sab:pec with a Seyfert2 spectrum and NGC 5930 is a $B\rm _T$ 13.5 mag SABbpec, and their difference in optical radial velocity is 150 km s^-1. H I line absorption was detected towards the nuclear region of NGC 5929 with MERLIN (Cole et al. 1998).

UGC 9858: our integrated line flux (30 Jy km s^-1) is lower than the 40-50 Jy km s^-1 measured at Green Bank. This may well be due to missed flux at Nançay, as the E-W D₂₅ diameter of the galaxy is about $4'\,\hspace{-1.7mm}.\hspace{.0mm}2$ , somewhat larger than the E-W HPBW of $3'\,\hspace{-1.7mm}.\hspace{.0mm}6$ . Our center velocity and linewidth are comparable to the published values, however.

A grid of pointings with 5' spacing in this group was mapped at Arecibo (Zwaan 2000, 2000) as part of a targeted search for H I clouds in galaxy groups. No such clouds were detected at an rms noise level of $\sim$ 0.75 mJy for a 10 km s^-1 resolution, implying a 5 $\sigma$ upper limit of about $6.5\times 10^{6}$ ${M}_\odot$ for H I clouds with an H I linewidth of 10 km s^-1 at the distance we adopted for this group, 27.2 Mpc.

NGC 5951: short Westerbork H I synthesis observations (Rhee & van Albada 1996) show an H I diameter of $3'\,\hspace{-1.7mm}.\hspace{.0mm}4$ at a surface density level of 1 ${M}_\odot$ pc^-2, 1.1 times the optical D₂₅ diameter. Two integrated line flux measurements of the galaxy are considerable higher than the $\sim$ 18 Jy km s^-1measured in 5 other studies, for unclear reasons: the 32.5 Jy km s^-1measured at Arecibo by Freudling (1995) and the 27.6 Jy km s^-1 measured at Jodrell Bank by Staveley-Smith & Davies (1988).

NGC 5953/4 pair: was mapped in H I at the VLA (Chengalur et al. 1994). R-band CCD imaging shows that the galaxies are joined by a broad stellar bridge, while NGC 5953 shows an extension towards the north-west. At this position angle an H I plume extends from the galaxy. The overall H I distribution is complex, as is the velocity field, particularly that of NGC 5953 and no clear picture can be drawn of the various kinematical components and their relation to the two galaxies. The total measured H I mass of the system is 1.3 $\times$ 10⁹ ${M}_\odot$ (equivalent to $F_{\rm HI}=8.0$ Jy km s^-1), of which the authors could readily associate 0.2 $\times$ 10⁹ and 0.5 $\times$ 10⁹ ${M}_\odot$ with NGC 5953 and 5954, respectively. NGC 5953 is an SAa:pec with a LINER/Seyfert2, and NGC 5954 an SAB(rs)cd:pec with a Seyfert2 spectrum.

In our Nançay profile, two adjacent but distinct peaks can be seen, one with V=1700 km s^-1, $I_{\rm HI}=3.4$ Jy km s^-1, W₅₀=116 km s^-1 and W₅₀=133 km s^-1, and the other with V=1966 km s^-1 and W₅₀=146 km s^-1. Nançay and Green Bank profiles centered on the NGC 5953/4 pair will be confused by H I emission from nearby UGC 9902, a $B\rm _T$ 17 mag, $0'\,\hspace{-1.7mm}.\hspace{.0mm}9$ diameter SBdm? spiral located 3' due south of the pair. Chengalur et al. (1994) note its VLA detection without giving detailed global profile parameters. At Arecibo, whose small beam should avoid confusion with the NGC 5953/4 pair, Haynes (1981) measured V=1695 km s^-1, W₅₀=106 km s^-1 and an integrated H I line flux of 3.4 Jy km s^-1 for UGC 9902 (compared to 8.0 for the NGC 5953/4 pair). We therefore conclude that the 1700 km s^-1 peak in our spectrum is due to nearby UGC 9902.

NGC 5962: Nançay profiles of this galaxy (V=1957 km s^-1, $I_{\rm HI}=16$ Jy km s^-1) will be slightly confused by UGC 9925, a $B\rm _T$ 15.4 mag Sc spiral $10'\,\hspace{-1.7mm}.\hspace{.0mm}1$ due south of it. Arecibo H I profiles of UGC 9925 (Lewis et al. 1985; Sulentic & Arp 1983), which are certainly not confused by NGC 5962 due to the small HPBW, show it has V=1916 km s^-1, FWHM=182 km s^-1 and $I_{\rm HI}=1.9$ Jy km s^-1. One Green Bank observation (Magri 1994) has a much smaller line flux (7.0 Jy km s^-1) than the average 16 Jy km s^-1 found in 7 other studies.

4.1.2 Control group sample

NGC 2998: short Westerbork observations (Broeils & van Woerden 1994) show its H I distribution to be symmetric but not very extended compared to its optical dimensions. Full Westerbork H I synthesis mapping (Broeils 1992) show that its H I disk has a diameter of $3'\,\hspace{-1.7mm}.\hspace{.0mm}8$ (1.3 D₂₅) and a regular velocity field with a classical, flat rotation curve at $V_{\rm rot}=210$ km s^-1.

Three small spiral companions were detected in H I at Westerbork: NGC 3002, NGC 3006 and MCG 07-20-057. These are $B\rm _T$ 15-16 mag objects at distances of 5' to 12' from NGC 2998, of about $0'\,\hspace{-1.7mm}.\hspace{.0mm}65$ diameter and with integrated H I fluxes ranging from 1.7 to 5.1 Jy km s^-1 at about the same systemic velocity as NGC 2998 (Broeils 1992). They lie well outside the Nançay HPBW, but can cause some confusion in Green Bank and Jodrell Bank profiles of NGC 2998. Our Nançay profile (estimated $I_{\rm HI}=17.5$ Jy km s^-1) agrees well with that of Theureau et al. (1998). The Green Bank (7.0 Jy km s^-1) and Jodrell Bank fluxes (31.9 Jy km s^-1) are quite different, though central velocities and linewidths are consistent between all available profiles.

Table 6: Published H I line data - interacting group sample.
GH Ident. $V_{\rm HI}$ $I_{\rm HI}$ W₅₀ W₂₀ Tel. Ref. Ident. $V_{\rm HI}$ $I_{\rm HI}$ W₅₀ W₂₀ Tel. Ref.

No. kms^-1 Jy kms^-1 kms^-1 kms^-1 kms^-1 Jy kms^-1 kms^-1 kms^-1

(1) (2) (3) (4) (5) (6) (7) (8) (2) (3) (4) (5) (6) (7) (8)

45 N2798* 1740 11.1 339 348 G PS74 N2798/9 1740 10.9 380 G PS74

1744 8.6 236 G H82 N2799* 1757 9.6 G DS83

1778 9.0 G DS83 1755 11.1 343 385 N B82

1726 11.1: 274 345 N B80 1865 2.0 121 V N97

1669 3.2 175 N vB85 N2844 1486 5.8 310 G H82

1747 3.0 277 V N97 1479 7.0 329 G M94

58 N3162 1290 21.5 164 237 A BC79 N3189 1373 6.2 605 A WR87

1302 26.6: 176 190 G DR78 1518 6.8 G DS83

1373 6.2 605 A WR87 1314 4.4 478 N BC83

1302 28.6 178 191 J D80 1320 5.1 528 V W91

1302 44.1 183 273 N B82 N3189/90 1302 4.1 457 A Ha81

N3177 1299 6.1 180 A KS80 N3193 <0.4 V W91

1296 3.3 204 A Ha81 N3213 1347 1.7 160 A BG87

1317 5.1 195 301 A BC79 N3227* 15.2: A DS83

1303 6.4: 230 410 N B82 1169 6.8: 387: A C87

N3185 1218 6.1 241 A KS80 1146 12.8: 526: A M82

1234 3.4 278 A Ha81 1146 526: A MW84

1226 3.7 253 A WR87 1152 13.3: 407 475 A B79

1237 7.3: 266 G H82 1138 28.6: 364 471 E HB75

1239 3.5 253 N BC83 1165 18.4: 109 374 G P79

1200 3.3 308 V W91 1148 14.1: G DS83

N3187 1577 8.3 A DS83 1106 20.2: 366: 400: G H78

1580 10.7 245 A WR87 1199 18.9: 258 300 J LD73

1579 10.5 224 276 A GS85 20.7 V W95

1579 9.6 262 A Ha81 N3239 754 53.0 144 A He81

1558 7.5: G H82 756 60.9 A DS83

1581 12.6 G DS83 754 88.0 160 205 G FT81

1582 10.3 219 243 J S88 755 80.2: 153 192 G S78

1573 24.6: 220 383 N B82 751 73.2: 157 210 G DR78

1591 14.2 261 N BC83 750 78.8 197 G TC88

1541 10.6 277 V W91 751 73.2 G43 DS83

N3189 1310 3.2 441 A LS84 751 G RD76

67 N3381 1627 21.0 80 A KS80 U6070 1849 6.2 118 A BG87

1631 8.5 56 125 A L87 N3430 1586 44.1 340 A HS82

1630 11.5 117 A M94 1594 42.1 337 351 G DR78

N3395* 1620 20.2 176 225 A L85 1577 57.1 338 370 J S88

1621 16.0 223 A J87 1583 G T78

1631 38.4: 134: 228 G S75 1594 G RD76

1621 G RD76 1583 F71

1605 G43 F71 N3442 1729 4.2 120 196 A T81

1625 V C99 1732 3.1 147 A BG87

N3396* 1625 26.1 162 A KS80 3.1 130 A BG87

1684 V C99 1736 2.0 143 A J87

N3395/6 26.0 V C99 1731 9.1 161 A M94

N3424 1501 14.0 353 A HS82

86 N3786* 2672 12.1 A DS83 N3786* confused A/W OS93

2707 9.1 545 A MW84 N3788* 2687 9.4 501 562 A L85

2725 4.9 331 401 A L85 2712 13.0 391 516 A S86

2770 8.1: 288 452 A S86 2673 11.8 509 A M94

2703 9.7 480 A M94 confused A/W OS93

2718 15.4 G DS83

92 N3902 3601 8.8 239 261 A L85 N3997 4765 8.8 295 A Wi86

N3920 3640 6.9 184 218 N G94 4771 7.0 283 A GZ87

U6806 3760 4.2 265 A Wi86 N4005 4458 2.0 402 A Wi86

I746 5027 7.4 271 309 A L85 4470 2.1 463 A GZ87

5030 6.7 310 A Wi86 4469 1.4 360 A C93

5027 7.7 293 A GZ87 N4015 4368 2.8 522 700 E H95

N3987 4501 7.9 557 A Wi86 N4015A* <1.3 A Wi86

4495 6.6 575 A GZ87 N4015B* 4347 2.3 815 A Wi86

4500 575 A M93 N4022 <1.8 A Wi86

N3987 4502 6.7 543 A C93

**Table 6:** continued.
GH	Ident.	$V_{\rm HI}$	$I_{\rm HI}$	W₅₀	W₂₀	Tel.	Ref.	Ident.	$V_{\rm HI}$	$I_{\rm HI}$	W₅₀	W₂₀	Tel.	Ref.
No.		kms^-1	Jy kms^-1	kms^-1	kms^-1				kms^-1	Jy kms^-1	kms^-1	kms^-1
(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(2)	(3)	(4)	(5)	(6)	(7)	(8)

126	N5341	3648	6.2	246		G	P79	N5394*	3490	32.0:	454		A	KS80
	N5351	3630	18.4	421	458	G	P79		3472	18.4	511	601	N	T98
		3377	23.1	420	445	J	S87	N5395*	3490	32.0:	454		A	KS80
		3605	19.2	445	528	N	B82		3445	16.0		606	A	SA83
		3610	20.2	407	443	W	R96		3544	24.5			G	DS83
		3611				G	T78		3459	28.3	470		G	RH91
	N5378	2947	11.2	440	490	G	RH91		3498	22.9	540	632	J	S87
		2990		325	335	N	T98		3505	17.9:	570:	681:	N	B82
	N5380		<1.3			A	C87		3459	29.9			N	C77
			<6.3			E	H82

141	N5529	2878	41.3	597	596	G	FT81	N5545*	3079	4.4	298	286	A	F95
		2882	37.7	571	606	G	S78		3051	4.2			G	DS83
		2882	27.1	570	603	A	L85		3088	6.0	350	430	N	B82
		2888	41.0	561	587	J	S88	N5589	3394	0.53	171	186	A	HR89
		2880	41.0	585	630	G	RH91			<5.4			G	RH91
		2895	36.3	557	600	W	R96	N5614	3884	2.3	126	219	A	HR89
	N5533	3867	8.3	451	465	A	Le85		3889	3.7			G	DS83
		3867	8.3	451	465	A	L85		3934	4.2	250	285	G	RH91
		3864				G	T78		3899	5.8:	220		N	B80
		3859	12.0			G	RH91	N5656		<3.0			A	KS80
		3858	35.3	409	439	W	BW94		3156	7.9	359	393	A	HR89
	N5544*	3072	3.3	253	286	A	SK78		3150	6.1	350	366	N	T98
		3086	4.1	239	274	A	L87	N5675		<4.5			A	H83
		3078	2.2		234	E	H97			<3.1			A	HR89
		3090	3.0	220	245	G	RH91	N5695	4225	1.6		376	A	MW84
	N5545*	3084	4.3			A	DS83		4255	2.7	338	364	A	HR89

153	N5929*	2561	3.1	211		E	H82	U9858	2619	50.6	366	381	G	FT81
	N5930*	2498	4.1	325	385	G	RH91		2630	41.0			G	DS83
		2530				N	T98		2622				G	T78

156	N5951	1776	17.9		279	A	Ha81	N5953*	1969	5.4		283	A	M88
		1782	16.0	263	289	A	GS85		1965	7.3	136		A	C93
			32.5	293	292	A	F95		1950	7.0:	158:	235:	N	B82
		1784	20.2	264	227	G	FT81		1921:		280:		V	C94
		1779	19.1		288	G	TC88	N5954*	1935	7.2		275	A	Ha81
		1777	27.6	264	277	J	S88		1938	5.9			A	DS83
		1779	20.2	265	282	W	R96		1960	7.4	146	279	A	L85
	N5962	1955	17.1:	346		A	KS80		1955	7.8	126	235	A	GS85
		1957	15.4	345		A	G87		1971	6.9	125		A	G87
		1958	13.2		364	A	M88		1964	7.2	133		A	C93
		1958	16.7	343		A	C93			13.1	276	275	A	F95
		1963	17.6:	342	354	G	S78		2000	4.1:			G	S78
					362	G	S78		1969	9.1:			N	B82
		1948	7.0	351		G	M94		1903		217		V	C94
		1960	15.0	350	412	N	B82	N5953/4		8.0			V	C94
	N5953*	1964	6.5	140		A	G87

NGC 3009: our narrow "detection'' seen in Fig. 1b is in fact spurious and due to radio interference, which occurs in the H polarization only. The upper limit listed in Table 6 was derived from the unaffected V polarization data only. This Sc spiral was reported as detected at Green Bank by Haynes et al. (1988), who noted that their spectrum is probably confused with NGC 3010, which lies well outside the Nançay beam. Their spectrum shows a broad component between $\sim$ 4470 and 4900 km s^-1 at the 8 mJy level and a narrow ( $\sim$ 120 km s^-1 FWHM) 17 mJy peak at $\sim$ 4570 km s^-1. As the optical velocities of NGC 3009 and 3010 are $4604\pm50$ and $4401\pm44$ km s^-1, respecively (LEDA), the association of the 4570 km s^-1 peak with NGC 3009 seems plausible; surprisingly, we did not detect this peak with our 2.9 mJy rms noise level.

UGC 5295: Our integrated line flux (16.8 Jy km s^-1) is comparable to the Green Bank value of 19.6 Jy km s^-1 from Haynes et al. (1988) but considerable higher than the Nançay value of 11.5 Jy km s^-1 reported by Bottinelli et al. (1982).

NGC 3156/65/66/69: H I in the NGC 3169 group, i.e. the Garcia 192 group (Garcia 1993), was mapped at Arecibo in the NGC 3165/66/69 area by Haynes (1981) and extended towards NGC 3156 by Duprie & Schneider (1996). These observations show complex H I distributions and kinematics: H I is definitely associated with NGC 3166 and NGC 3166, and detected at and near the position of NGC 3165, but the physical association of this emission with this late-type spiral is unclear. No H I is detected in the S0 NGC 3156; the rms noise of Duprie & Schneider, 1.98 mJy, gives an upper limit of 1.8 Jy km s^-1 to the integrated line flux. The estimated total H I line flux of the group is 128 Jy km s^-1 from the Arecibo mapping of Haynes et al. (1981) and 105 Jy km s^-1 from the Nançay mapping by Balkowski & Chamaraux (1983). Clearly, the 3 Nançay pointings (centered on NGC 3165, 3166 and 3169) will not cover the extended H I distribution of the group. The extension of the H I distribution is also evident from the flux densities of spectra taken in the direction of NGC 3166: 39.1 Jy km s^-1 at Green Bank, 12 at Nançay and 3.5 at Arecibo. Our linewidths for NGC 3166 are much narrower than the 2 literature values, probably due to complex confusion in its vicinity; Haynes (1981) noted a narrow velocity component (presumably associated with the galaxy) superposed on a broad component at and near the galaxy's position. For NGC 3169, compared to our Nançay integrated line flux (59 Jy km s^-1), the two published Nançay spectra have either a much larger (99 Jy km s^-1) or a much smaller (24 Jy km s^-1) flux, and the latter (Bottinelli et al. 1970) has a much smaller W₅₀ width, though its W₂₀ width is comparable to ours. NGC 3166 is an SABO^-a with a LINER spectrum, and NGC 3169 is an SA(s)apec with a LINER spectrum.

UGC 6617: lenticular galaxy, not detected in our survey (estimated $I_{\rm HI}<2.0$ Jy km s^-1). The Arecibo upper limit of 1.5 Jy km s^-1 listed in Table 7, from Williams (1985), has been corrected to the line width of 300 km s^-1 used for upper limits throughout the present paper. We assume this to be a 3 $\sigma$ upper limit, though this is not mentioned explicitly in Williams' paper.

NGC 3817: our integrated line flux of 2.1 Jy km s^-1 is much higher than the Arecibo value of $1.1\pm0.23$ Jy km s^-1 reported by Williams (1985), but our detection has a peak flux density of 3.5 $\sigma$ only and our line flux is therefore not very accurate.

NGC 3822/5: pair of spirals not clearly detected in our survey (estimated $I_{\rm HI}<2.4$ Jy km s^-1). The pair is oriented practically East-West, with a separation of $3'\,\hspace{-1.7mm}.\hspace{.0mm}1$ , somewhat smaller than the Nançay E-W HPBW and the Arecibo HPBW. Our non-detection is surprising, given the integrated Arecibo line fluxes of 3.6 and 0.8-1.6 Jy km s^-1 reported for NGC 3822 and 3825, respectively, by Eder et al. (1991) and Williams (1985). This may indicated the presence of extended H I emission outside the Nançay beam area. NGC 3822 has a Seyfert2 spectrum.

IC724: our integrated line flux (2.6 Jy km s^-1) is lower than the 3.5-4.8 Jy km s^-1 measured at Arecibo, and our W₅₀ value (497 km s^-1) is somewhat smaller than the $\sim$ 540 km s^-1 measured at Arecibo.

NGC 3843: S0/a galaxy, not detected in our survey (estimated $I_{\rm HI}<2.1$ Jy km s^-1). The upper limit to its H I gas content, ${M}_{\rm HI}$ /L_B $\,<\,$ 0.13 ${M}_\odot$ / $L_{\odot,B}$ , is consistent with its morphological classification.

Table 7: Published H I line data - control group sample.
GH Ident. $V_{\rm HI}$ $I_{\rm HI}$ W₅₀ W₂₀ Tel. Ref. Ident. $V_{\rm HI}$ $I_{\rm HI}$ W₅₀ W₂₀ Tel. Ref.

No. kms^-1 Jy kms^-1 kms^-1 kms^-1 kms^-1 Jy kms^-1 kms^-1 kms^-1

(1) (2) (3) (4) (5) (6) (7) (8) (2) (3) (4) (5) (6) (7) (8)

49 N2998 4766 7.0 386 G M94 N2998 4790 20.1 382 394 W BW94

4777 G T78 4781 21.4 394 417 W B92

4700 G FT81 N3009 4666 3.7 103 443 G H88

4777 31.9 374 392 J S88 U5295 4790 19.6 286 G H88

4784 14.7 373 389 N T98 4771 11.5 261 332 N B82

57 N3156 1.4 690 A K79 N3166 1283 3.5 435 A Ha81

<1.8 A DS96 1418 4.6 A DS83

<1.0 A K78 1328 39.1: 177 G H82

<0.7 A G83 N3166/9 1239 105.0 443 N BC83

N3165 1335 3.3 150 A Ha81 N3169 1234 42.5 A DS83

1328 3.9 139 156 A L85 1227 58.1 481 A Ha81

1332 4.9 141 N BC83 1240 96.0 537 G DS83

1340 2.9 157 173 A S90 1229 25.0:: 195: 505: N B70

1356 7.9 159 -- A DS96 1240 98.9 N B79

89 U6617 <1.5 A W85 N3825* 6323 0.8 393 A W85

N3817 6079 1.1 326 A W85 I724 5972 3.5 551 A W85

N3822* 6164 3.6 545 552 A E91 5963 4.2 543 545 A E91

6168 4.2 521 A M94 5973 4.8 538 A M94

6166 3.6 559 A W85 N3839 5910 10.1 366 A W85

N3825* 6381 1.6 611 608 A E91

118 N5141 <7.2 A DS83 N5149 5660 6.6 453 462 N T98

N5142 <6.0 A OS93 N5149/55 confused A/W OS93

123 N5289 2516 8.8 371 G P79 N5337 not detected W OS93

2525 7.3 360 374 W V83 N5350* 2198 23.1 265 435 N B82

2521 9.0 401 G TC88 2316 30.5 282 298 G FT81

2493 9.7 380 N Pun 2322 29.9 292 316 J S87

N5290 2579 12.1: 469 484 G FT81 2321 30.2 295 332 W RA96

2583 10.4 461 G P79 N5354* 2304 19.1 266 301 E RH91

2571 11.1 453 475 W V83 N5353 2307 17.7 300 308 E RH91

2589 11.7 444 473 J S87 2310 17.1 300 388 E H94

2572 10.6 482 G TC88 <10.7 G DS83

N5297 2406 417 480 N B82 N5355 2313 14.7 289 305 E RH91

2392 52.0: 402 423 J D80 2340 17.5 290 336 G WR86

2404 52.0 394 427 G FT81 N5362 2166 8.2 258 272 E RH91

2411 52.0 G DS83 2169 7.0 274 G M94

2405 54.0 G43 DS83 2182 7.1 264 280 N T98

N5311 2645 5.1 390 425 G RH91 2175 9.5 296 W K96

U8736 <8.1 G RH91 N5371 2557 40.2: 384 420 G S78

N5313 2540 12.1 448 478 N B82 2555 33.4: 377 399 J D80

2537 8.4 421 G P79 2541 29.1 400 475 N B82

N5320 2613 25.4 300 313 G FT81 2554 26.6 382 411 W We86

2619 28.6 300 313 J SD88 30.1 W B87

2609 7.0 314 G M94 N5383 2264 15.3: 306: 339: G P78

N5326 <2.7 G RH91 2268 G T78

not detected W OS93 2165 27.0: 309 346 G TM81

2520 1.8 335 337 N T98 2265 28.1 290 327 J SD87

N5336 2324 7.0 218 G M94 2282 36.0 382 497 N B82

2338 5.4 211 216 N T98 2264 22.0 303 327 W A74

N5337 2125 1.8 344 355 G GH91 2264 22.1 315 340 W S79

2102 3.3 370 429 N T98

155 N5945 5516 3.7 356 456 N T98 I4567 5722 G T78

<5.4 G RH 91 5795 15.5 380 430 G RH91

I4564* 5961 7.5 494 624 A GH91 5711 7.0 330 G M94

I4566* <4.5 G RH 91 5737 6.0 320 337 N T98

5767 1.5 289 326 N T98

Note: ":'' denotes an uncertain value.

NGC 5141 and NGC 5142: two S0 galaxies, not detected in our survey (estimated $I_{\rm HI}<2.3$ and <2.2 Jy km s^-1, and ${M}_{\rm HI}$ /L_B $\,<\,$ 0.11 and <0.16 ${M}_\odot$ / $L_{\odot,B}$ , respectively).

NGC 5149: Detected at Nançay by Theureau et al. (1998) and in the present survey (at $I_{\rm HI}$ 4.7, 6.6 Jy km s^-1, respectively). Oosterloo & Shostak (1993) did not detect it at Arecibo, but the H I line is too weak for a clear detection at their rms level of 6.6 mJy; in their short Westerbork observations of the NGC 5149/5154 ( $=\!\rm UGC$ 8444/54) pair the signal of NGC 5149 is confused with that of its companion. No confusion with NGC 5154 is expected for the Nançay spectra, since it has an E-W separation of $3'\,\hspace{-1.7mm}.\hspace{.0mm}8$ from NGC 5149.

NGC 5289/90 pair: mapped in H I at Westerbork (van Moorsel 1983). The H I distribution of NGC 5289 is clearly asymmetric, with an extension towards the NW away from the plane, possibly due to interaction with NGC 5290, which itself does not seem to be affected. The H I kinematics does not indicate that the interaction was important, as reliable classical flat H I rotation curves could be derived from the velocity fields: $V_{\rm rot, max}$ is $\sim$ 180 and 225 km s^-1 for, respectively, NGC 5289 and NGC 5290. The E-W H I diameters of NGC 5289 and 5290 measured at Westerbork are $3'\,\hspace{-1.7mm}.\hspace{.0mm}9$ and 37, respectively. The $3'\,\hspace{-1.7mm}.\hspace{.0mm}6$ Nançay E-W HPBW should therefore cover the entire H I emission of each object, as shown by the agreement between our profile parameters and the literature values.

NGC 5311: S0/a galaxy, at $V_{\rm opt}=2698\pm40$ kms^-1, not detected in our survey (estimated $I_{\rm HI}<2.4$ Jy km s^-1). Detected at Green Bank (Richter & Huchtmeier 1991), with a considerably higher integrated line flux, 5.1 Jy km s^-1, at V=2645 km s^-1, with W₅₀=453 km s^-1. The Green Bank profile could in principle be confused with NGC 5313, a $B\rm _T$ 12.8 mag, Sbc type spiral $9'\,\hspace{-1.7mm}.\hspace{.0mm}3$ due East of NGC 5311, with $V_{\rm opt}=2597\pm44$ km s^-1. Three H I detections of NGC 5313 are available: one from Green Bank (Peterson 1979) and two from Nançay (Bottinelli et al. 1982; the present survey); in principle, the Nançay detections should not be confused by emission from NGC 5311. The H I profile parameters of NGC 5313 are V=2551 km s^-1, $I_{\rm HI}=9.5$ Jy km s^-1 and W₅₀=421 km s^-1. Because the separation between the two galaxies is comparable to the size of the Green Bank beam, the "detection'' of NGC 5311 could be due to the higher velocities in the NGC 5313 profile.

NGC 5320: of the 4 the available Green Bank, Jodrell Bank and Nançay profiles, the Green Bank profile of Magri (1994) is discrepant, having $\sim$ 3.5 times smaller integrated line flux (7 Jy km s^-1), though its central velocity and linewidths are comparable to those of the others.

NGC 5326/5337: short Westerbork H I synthesis observations were made of this pair (Oosterloo & Shostak 1993), but the galaxies were not detected at an rms noise level of 3.0 mJy/beam (resolution 25'').

NGC 5336 our integrated line flux (7.7 Jy km s^-1) is higher than the 5.4 Jy km s^-1 measured at Nançay by Theureau et al. (1998). This general tendency, due to differences in calibration procedures, has already been discussed in Matthews et al. (2000), and references therein.

NGC 5350/3/4/5 area: 5 galaxies constitute Hickson Compact Group 68: NGC 5350, 5353, 5354, 5355 and 5358 (Hickson 1982). NGC 5350/3/4: three closeby galaxies are located near the centre of the Nançay beam in the pointings towards NGC 5350/4 and NGC 5353: the SBb spiral NGC 5350 ( $V_{\rm opt}=2321\pm61$ km s^-1) and the early-type (E/S0) systems NGC 5353 ( $V_{\rm opt}=2166\pm103$ km s^-1) and NGC 5354( $V_{\rm opt}=2681\pm244$ km s^-1). In principle, Arecibo or radio synthesis observations could separate the H I emission from the galaxies, but no Arecibo data are available (see Table 7), and no mention was made of the detection of H I in either NGC 5353 or NGC 5354 in the short Westerbork observations of NGC 5350 (Rhee & van Albada 1996). As we do not expect the two early-types to be detectable in H I, and as our two Nançay profiles have very similar profile parameters, we will assume that all gas detected in our Nançay profiles actually resides in NGC 5350. The Rhee & van Albada Westerbork data show an H I diameter of $4'\,\hspace{-1.7mm}.\hspace{.0mm}4$ at a surface density level of 1 ${M}_\odot$ pc^-2, 1.1 times the optical D₂₅ diameter. NGC 5355: we detected H I in the Nançay spectrum taken towards NGC 5355, an early-type galaxy (classified as S0 or E). Gas-rich S0 galaxies, though rare, do exist (e.g., Wardle & Knapp 1985), and often with large H I distributions (van Driel & van Woerden 1991), but our NGC 5355 H I profile closely resembles the high-velocity half of our strong detection of the large spiral NGC 5350, located $4'\,\hspace{-1.7mm}.\hspace{.0mm}5$ W of NGC 5355, though with a six times reduced flux density. We therefore consider this "detection'' to be of nearby NGC 5350. In principle, our NGC 5355 Nançay spectrum might be confused with $B\rm _T$ 14.6 mag, S0/a NGC 5358, located $3'\,\hspace{-1.7mm}.\hspace{.0mm}0$ E of it, but the only H I "detection'' of this object (Richter & Huchtmeier 1991) seems spurious, as its central velocity of 1547 km s^-1 is completely discrepant with the optical velocities of all nearby galaxies, including that of NGC 5358 itself ( $2432\pm60$ km s^-1, based on 2 published measurements).

NGC 5362: short Westerbork H I synthesis observations (Kamphuis et al. 1996) were obtained of this object to determine global H I profile parameters (see Table 7); no further morphological or kinematical H I data are given.

NGC 5371: this SAB(rs)bc with a LINER spectrum, was mapped in H I at Westerbork (Wevers et al. 1986). Its optical luminosity profile shows a sharp edge at a radius of about 100'', beyond which the surface brightness drops rapidly and the disk becomes redder. Its H I distribution is ring-shaped with a maximum surface density of 80'' radius, and having an outer edge coinciding with the optical edge. Its velocity field shows signs of a mild warp, and a flat rotation curve was derived from it with a $V_{\rm rot, max}$ of 300 km s^-1.

NGC 5383: this barred SBb system was mapped in H I at Westerbork (Sancisi et al. 1979). The atomic hydrogen is largely concentrated in the optically bright central parts, and deficient in the region of the bar. Its kinematics are regular, with deviations of order 50-100 km s^-1 near the bar (similar to those found in other barred galaxies). A classical flat rotation curve was derived from the velocity field with $V_{\rm rot,max}=210$ km s^-1.

At Westerbork, H I emission was also detected from the SBdm companion UGC 8877, located 3' South of NGC 5383. The published single-dish H I data for NGC 5383, as well as our data, will be only slightly confused by its presence, as its integrated H I flux is 1.7 Jy km s^-1, i.e. 8% of the integrated H I flux of NGC 5383 as measured at Westerbork. Its central velocity, 2370 km s^-1, is 120 km s^-1 higher than that of NGC 5383. The integrated H I line flux we measured for NGC 5383 (18.0 Jy km s^-1) is comparable to the Westerbork value of 22.0 Jy km s^-1, though it is twice as small as the previously published Nançay value (Bottinelli et al. 1982).

Table 8: References and telescope codes to Tables 6 and 7.
A74 Allen et al. (1974) B79 Balkowski (1979) BC83 Balkowski & Chamaraux (1983)

B87 Begeman (1987) BG87 Bicay & Giovanelli (1987) BC79 Biermann et al. (1979)

B70 Bottinelli et al. (1970) B80 Bottinelli et al. (1980) B82 Bottinelli et al. (1982)

B92 Broeils (1992) BW94 Broeils & van Woerden (1994) C77 Chamaraux (1977)

C87 Chamaraux et al. (1987) C93 Chengalur et al. (1993) C94 Chengalur et al. (1994)

C99 Clemens et al. (1999) D80 Davies (1980) DS83 Davis & Seaquist (1983)

DR78 Dickel & Rood (1978) DS96 Duprie & Schneider (1996) E91 Eder et al. (1991)

FT81 Fisher & Tully (1981) F71 Ford et al. (1971) F95 Freudling (1995)

G87 Garwood et al. (1987) G94 Garcia et al. (1994) GZ87 Gavazzi (1987)

G83 Giovanardi et al. (1983) GS85 Giovanardi & Salpeter (1985) Ha81 Haynes (1981)

H88 Haynes et al. (1988) H78 Heckman et al. (1978) H83 Heckman et al. (1983)

H94 Huchtmeier (1994) H97 Huchtmeier (1997) HR89 see Huchtmeier & Richter (1989)

He81 Helou et al. (1981) HS82 Helou et al. (1982) H82 Huchtmeier (1982)

H95 Huchtmeier et al. (1995) HB75 Huchtmeier & Bohnenstengel (1975) J87 Jackson et al. (1987)

K78 Knapp et al. (1978) K79 Knapp et al. (1979) K96 Kamphuis et al. (1996)

KS80 Krumm & Salpeter (1980) LS84 Lake & Schommer (1984) Le85 Lewis (1985)

L85 Lewis et al. (Lewis 85) L87 Lewis (1987) LD73

M94 Magri (1994) M82 Mirabel (1982) MW84 Mirabel & Wilson (1984)

M88 Mirabel & Sanders (1988) M93 Mould et al. (1993) N97 Nordgren et al. (1997)

OS93 Oosterloo & Shostak (1993) PS74 Peterson & Shostak (1974) P78 Peterson et al. (1978)

P79 Peterson (1979) Pun Paturel (1998) R96 Rhee & van Albada (1996)

RH91 Richter & Huchtmeier (1991) RD76 Rood & Dickel (1976) S79 Sancisi et al. (1979)

S86 Schneider et al. (1986a) S90 Schneider et al. (1990) S75 Shostak (1975)

S78 Shostak (1978) SK78 Silverglate & Krumm (1978) S87 Staveley-Smith & Davies (1987)

S88 Staveley-Smith & Davies (1988) SA83 Sulentic & Arp (1983) T78 Thonnard et al. (1978)

T81 Thuan & Martin (1981) T98 Theureau et al. (1998) TC88 Tifft & Cocke (1988)

vB85 van der Burg (1985) V83 van Moorsel (1983) W85 Williams (1985)

We86 Wevers et al. (1986) Wi86 Williams (1986) WR87 Williams & Rood (1987)

W91 Williams et al. (1991)

A Arecibo 305 m E Effelsberg 100 m G Green Bank 91 m

G43 Green Bank 43 m J Joddrell Bank 64 m N Nançay 94 m equiv

V VLA W Westerbork

**Table 8:** References and telescope codes to Tables 6 and 7.
A74	Allen et al. (1974)	B79	Balkowski (1979)	BC83	Balkowski & Chamaraux (1983)
B87	Begeman (1987)	BG87	Bicay & Giovanelli (1987)	BC79	Biermann et al. (1979)
B70	Bottinelli et al. (1970)	B80	Bottinelli et al. (1980)	B82	Bottinelli et al. (1982)
B92	Broeils (1992)	BW94	Broeils & van Woerden (1994)	C77	Chamaraux (1977)
C87	Chamaraux et al. (1987)	C93	Chengalur et al. (1993)	C94	Chengalur et al. (1994)
C99	Clemens et al. (1999)	D80	Davies (1980)	DS83	Davis & Seaquist (1983)
DR78	Dickel & Rood (1978)	DS96	Duprie & Schneider (1996)	E91	Eder et al. (1991)
FT81	Fisher & Tully (1981)	F71	Ford et al. (1971)	F95	Freudling (1995)
G87	Garwood et al. (1987)	G94	Garcia et al. (1994)	GZ87	Gavazzi (1987)
G83	Giovanardi et al. (1983)	GS85	Giovanardi & Salpeter (1985)	Ha81	Haynes (1981)
H88	Haynes et al. (1988)	H78	Heckman et al. (1978)	H83	Heckman et al. (1983)
H94	Huchtmeier (1994)	H97	Huchtmeier (1997)	HR89	see Huchtmeier & Richter (1989)
He81	Helou et al. (1981)	HS82	Helou et al. (1982)	H82	Huchtmeier (1982)
H95	Huchtmeier et al. (1995)	HB75	Huchtmeier & Bohnenstengel (1975)	J87	Jackson et al. (1987)
K78	Knapp et al. (1978)	K79	Knapp et al. (1979)	K96	Kamphuis et al. (1996)
KS80	Krumm & Salpeter (1980)	LS84	Lake & Schommer (1984)	Le85	Lewis (1985)
L85	Lewis et al. (Lewis	85)	L87	Lewis (1987)	LD73
M94	Magri (1994)	M82	Mirabel (1982)	MW84	Mirabel & Wilson (1984)
M88	Mirabel & Sanders (1988)	M93	Mould et al. (1993)	N97	Nordgren et al. (1997)
OS93	Oosterloo & Shostak (1993)	PS74	Peterson & Shostak (1974)	P78	Peterson et al. (1978)
P79	Peterson (1979)	Pun	Paturel (1998)	R96	Rhee & van Albada (1996)
RH91	Richter & Huchtmeier (1991)	RD76	Rood & Dickel (1976)	S79	Sancisi et al. (1979)
S86	Schneider et al. (1986a)	S90	Schneider et al. (1990)	S75	Shostak (1975)
S78	Shostak (1978)	SK78	Silverglate & Krumm (1978)	S87	Staveley-Smith & Davies (1987)
S88	Staveley-Smith & Davies (1988)	SA83	Sulentic & Arp (1983)	T78	Thonnard et al. (1978)
T81	Thuan & Martin (1981)	T98	Theureau et al. (1998)	TC88	Tifft & Cocke (1988)
vB85	van der Burg (1985)	V83	van Moorsel (1983)	W85	Williams (1985)
We86	Wevers et al. (1986)	Wi86	Williams (1986)	WR87	Williams & Rood (1987)
W91	Williams et al. (1991)

A	Arecibo 305 m	E	Effelsberg 100 m	G	Green Bank 91 m
G43	Green Bank 43 m	J	Joddrell Bank 64 m	N	Nançay 94 m equiv
V	VLA	W	Westerbork

NGC 5934: our Nançay profile, with $V_{\rm HI}=5731$ km s^-1 and W₅₀=131 km s^-1, centered on this $B\rm _T$ 14.6 mag Sb spiral which has a $V_{\rm opt}=5603\pm33$ km s^-1, could in principle be confused with that of two galaxies of about similar magnitude and optical diameter: NGC 5935, a nearby ( $1'\,\hspace{-1.7mm}.\hspace{.0mm}1$ separation) $B\rm _T$ 15.1 mag Sb spiral having an optical redshift of $5373\pm60$ km s^-1 (Falco et al. 1999), and PGC55173 (CGCG 222-012), a $B\rm _T$ 15.5 mag Sb spiral at $4'\,\hspace{-1.7mm}.\hspace{.0mm}7$ due north having no published optical redshift. No published H I data are available for either of these objects. The close NGC 5934/5 pair actually shows signs of interaction on the blue POSS image, as the outer regions of NGC 5934 are turned towards NGC 5935, which appears to have a faint, stubby tail pointing away from NGC 5934. VLA continuum observations at 2 and 6 cm wavelength (Batuski et al. 1992) detected NGC 5934 only; these authors classified it as an elliptical(?). No optical emission lines were found in NGC 5934 (Sanduleak & Pesch 1987).

IC4567: of the 5 available Nançay and Green Bank data, only the Green Bank profile of Richter & Huchtmeier (1991) is discrepant, with a $\sim$ 70 km s^-1 higher central velocity, considerable larger widths and 2.4 times larger integrated line flux (15.5 Jy km s^-1); radio interference may well be the cause of this. There are no galaxies in the vicinity to cause confusion in the H I observations.

IC4562: elliptical galaxy, not detected in our survey (estimated $I_{\rm HI}\!\!<\!\!1$ .08 Jy km s^-1 and ${M}_{\rm HI}$ /L_B $\,<\,$ 0.08 ${M}_\odot$ / $L_{\odot,B}$ ).

IC4564/66: first, a single spectrum was obtained pointed towards the mean position of the galaxies' centers. Given the relatively large E-W separation of the galaxies in $\alpha$ ( $2'\,\hspace{-1.7mm}.\hspace{.0mm}8$ ) compared to the E-W HPBW of $3'\,\hspace{-1.7mm}.\hspace{.0mm}6$ , spectra were also obtained individually for the center position of each object. These data were used for Table 6.

IC4567: of the 5 available Nançay and Green Bank data, only the Green Bank profile of Richter & Huchtmeier (1991) is discrepant, with a $\sim$ 70 km s^-1 higher central velocity, considerable larger widths and 2.4 times larger integrated line flux (15.5 Jy km s^-1). Radio interference may well be the cause of this. There are no galaxies in the vicinity to cause confusion in the H I observations.

4.2 Integrated H I line fluxes

All cases where we measured a Nançay flux more than twice as large or more than twice as small as a flux reported in the literature are discussed in Sect. 4.1. These discrepancies are usually related to the presence of extended H I structures in the groups. In a few cases, a single Green Bank measurement differs significantly from other measurements made with the same telescope, which are consistent with our Nançay value. In one case only there is no clear explanation for the discrepancies between line fluxes: NGC 5533, where the Green Bank and Nançay values are much lower than the Westerbork measurement, though the Green Bank beam should have covered the H I disk.

The cases in which large differences were found between line fluxes measured by us and those reported in the literature are: (1) the Nançay-Green Bank comparison shows 5 galaxies or close galaxy pairs with an integrated Green Bank line flux at least twice as large as our Nançay value (in order of increasing Green Bank flux: NGC 3185, 5378, 3166, 3395 and 3239), and 3 galaxies with a Green Bank flux at least twice as small as our Nançay value (IC4567, NGC 2998 and 5320); (2) the Nançay-Arecibo comparison shows one object with an Arecibo flux more than twice as large as the Nançay value (NGC 3442) and 5 objects with an Arecibo flux less than twice the Nançay value (in order of increasing Arecibo flux: NGC 3166, 3786, 3227, UGC 6806 and NGC 5533); (3) a comparison between our Nançay data and profiles obtained earlier with the same telescope shows 2 objects with a literature Nançay flux more than twice as large as our value (in order of increasing flux: NGC 3187 and 5383) and one with a literature Nançay flux less than twice our value: GC3169.

4.3 H I profile linewidths

The cases in which large differences between measured linewidths were found are: (1.) The Nançay-Green Bank comparison shows 2 galaxies or close galaxy pairs with a Green Bank W₅₀ measurement more than twice as large as the Nançay value: NGC 3166 and 3226/7 (in order of increasing linewidth); (2) the Nançay-Arecibo comparison shows one object with an Arecibo W₅₀ measurement more than twice as large as the Nançay value (NGC 3226/7) and one with a W₂₀ more than twice as large as the Nançay value: NGC 3166.

5 Summary and conclusions

For galaxies which had been previously observed in the H I line, we generally find good agreement in radial velocities, while a larger scatter is seen for the H I line width parameters, especially W₂₀. The line widths are sensitive to the degree of resolution of the target galaxies, especially for the relatively small Arecibo beam, to the presence of tidal debris within the beams and to the quality of the data, in particular for W₂₀. The largest scatter is found in integrated H I fluxes, where differences of $\sim$ 50% are common between various observations obtained with the Green Bank 90-m, Arecibo 305-m and Nançay telescopes. Our knowledge of the H I content of even the giant members of relatively nearby groups of galaxy is rather poor.

In a future paper we will analyze the H I, optical and near-infrared properties of the "interacting'' and "control'' galaxy groups. We also plan to correlate H I properties with galaxy structural characteristics as determined from optical and near-infrared observations.

HI observations of loose galaxy groups

I. Data and global properties