1 Introduction

The present paper is the fourth in a series (I: Bottinelli et al. 1992; II: Bottinelli et al. 1993; III: di Nella et al. 1996) which intends to complement optical catalogues with new radial velocity, 21-cm line width, and HI-flux measurements. Our aim was to build a large sample of spiral galaxies, complete down to a photometric diameter of 1.6 arcmin, and having unbiased Tully-Fisher distances. First applications of this KLUN programme, dedicated to the study of the Kinematics of the Local UNiverse, started in 1990 (Paturel et al. 1990) and cover several topics of discussion on:

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the completeness of the sample (Paturel et al. 1994)

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the homogenization of optical and radio data in connexion with the Lyon-Meudon Extragalactic database LEDA (Bottinelli et al. 1990)

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the effect of disc opaqueness on observed optical B-band parameters (Bottinelli et al. 1995)

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the dependence of the TF relation on morphological type and mean surface brightness and the improvement of this distance indicator (Theureau et al. 1997a; Theureau 1998)

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the determination of the Hubble constant H₀ from TF B-band and $\log D_{25}$ relations (Theureau et al. 1997b).

We present here the result of our Nançay HI-survey, in the period between 1988 and 1996, from a catalogue of 2711 spiral galaxies (from Sa to Sdm). In addition to the 664 previously published (Papers I and II) radial velocities, we give 213 new velocity measurements, and 21-cm line widths and HI fluxes for 2112 objects of the observed sample, together with their 21-cm line profile, signal to noise ratio S, and rms noise $\sigma_{\rm ext}$.These new observations put to 6700 the number of spiral galaxies contained in our KLUN sample.

The Nançay radiotelescope and processing chain are briefly presented in Sect. 2. The actual detection rate is discussed in Sect. 3, and the data processing in Sects. 4, 5, and 6. Finally, Sect. 7 presents our conclusions on observational errors and completeness of the HI-sample.