ASTRONOMY & ASTROPHYSICS JUNE I 1998, PAGE 333 SUPPLEMENT SERIES Astron. Astrophys. Suppl. Ser. 130, 333–339 (1998) Kinematics of the local universe VII. New 21-cm line measurements of 2112 galaxies?,?? G. Theureau1, L. Bottinelli1,3, N. Coudreau-Durand1, L. Gouguenheim1,3, N. Hallet1, M. Loulergue1, G. Paturel4, and P. Teerikorpi2 1 Observatoire de Paris/Meudon, ARPEGES/CNRS URA1757, F-92195 Meudon Principal Cedex, France 2 Tuorla Observatory, 21500 Piikki¨o, Finland 3 Universit´e Paris-Sud, F-91405 Orsay, France 4 Observatoire de Lyon, F-69561 Saint-Genis Laval Cedex, France Received November 28; accepted December 24, 1997 Abstract. This paper presents 2112 new 21-cm neutral hy- • the completeness of the sample (Paturel et al. 1994) drogen line measurements carried out with the meridian • the homogenization of optical and radio data in con- transit Nan¸cay radiotelescope. Among these data we give nexion with the Lyon-Meudon Extragalactic database also 213 new radial velocities which complement those LEDA (Bottinelli et al. 1990) listed in three previous papers of this series. These new • the effect of disc opaqueness on observed optical B- measurements, together with the HI data collected in band parameters (Bottinelli et al. 1995) LEDA, put to 6 700 the number of galaxies with 21-cm • the dependence of the TF relation on morphological line width, radial velocity, and apparent diameter in the type and mean surface brightness and the improve- so-called KLUN sample. ment of this distance indicator (Theureau et al. 1997a; Theureau 1998) Key words: catalogs — galaxies: distances and redshifts; • the determination of the Hubble constant H0 from TF ISM — radio lines: galaxies B-band and log D25 relations (Theureau et al. 1997b). We present here the result of our Nan¸cay 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 veloci- 1. Introduction ties, we give 213 new velocity measurements, and 21-cm line widths and HI fluxes for 2112 objects of the observed The present paper is the fourth in a series (I: sample, together with their 21-cm line profile, signal to Bottinelli et al. 1992; II: Bottinelli et al. 1993; III: di noise ratio S, and rms noise σ . These new observations Nella et al. 1996) which intends to complement optical ext put to 6700 the number of spiral galaxies contained in our catalogues with new radial velocity, 21-cm line width, and KLUN sample. HI-flux measurements. Our aim was to build a large sam- The Nan¸cay radiotelescope and processing chain are ple of spiral galaxies, complete down to a photometric briefly presented in Sect. 2. The actual detection rate is diameter of 1.6 arcmin, and having unbiased Tully-Fisher discussed in Sect. 3, and the data processing in Sects. 4, distances. First applications of this KLUN programme, 5, and 6. Finally, Sect. 7 presents our conclusions on ob- dedicated to the study of the Kinematics of the Local servational errors and completeness of the HI-sample. UNiverse, started in 1990 (Paturel et al. 1990) and cover several topics of discussion on: Send offprint requests to: [email protected] 2. Observations ? Figure 5 and Appendices A and B for correspond- ing comments are available in electronic form at the The totality of these observations has been carried out http://www.edpsciences.com with the meridian-transit Nan¸cay radiotelescope (France). ?? Table 2 is only available in electronic form at the CDS This instrument is a single dish antenna with a collecting via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via area of 6912 m2 (200 × 34.56) equivalent to that of a 94 http://cdsweb.u-strasbg.fr/Abstract.html m-diameter parabolic dish. The half-power beam width at 334 G. Theureau et al.: Kinematics of the local universe. VII. 21-cm is 3.6 arcmin (EW) × 22 arcmin (NS) (at zero dec- lination). The minimal system temperature at δ =15◦ is about 37 K in both horizontal and vertical polarizations. The spectrometer is a 1024-channel autocorrelator of 6.4 MHz bandwidth. The spacing of the channels corresponds to 2.6 km s−1 at 21 cm with a bank of 512 channels in each polarization. After boxcar smoothing the final resolution is typically 10 km s−1. In the velocity-search mode the 1024 channels are split in four banks of 256 channels leading to a range of 4800 km s−1 (generally from 400 to 5200 km s−1 or from 5200 to 10000 km s−1). The gain of the antenna has been calibrated according to Fouqu´e et al. 1990; the final HI-fluxes (Table 2) are expressed by using as refer- ence a set of 9 calibrator galaxies regularly observed since 1988 (see Sect. 6). We used the Nan¸cay processing package SIR (Syst`eme Interactif de R´eduction). The processing chain consists of a selection of good observation cycles (one “observation” is a series of on/off observational sequences), the straight- ening of the base-line by a polynomial fit, and the appli- cation of a boxcar smoothing. The maximum of the line is determined by eye as the mean value of the maxima of each profile’s horn after taking into account the medium noise (evaluated in the base-line). The widths, measured at the standard levels 20% and 50% of that maximum, correspond to the “distance” separating the two external points of the profile at these intensity levels. The total list of corrected HI-astrophysical pa- rameters (Table 2), 21-cm line profiles (Fig. 5), and their corresponding comments (Appendix A and B), Fig. 1. detection rate as a function of: a) inclination, b) Type, c) radial velocity, for galaxies of known velocity is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html or via http://www.edpsciences.com. As an example, the first detection rate of 86.3% (In fact, almost 90% if confused page of Table 2 and Fig. 5 are presented at the end of profile due to close companions are taken into account). this paper. In the same way, for the velocity search mode which con- cerned 890 objects (hereafter Sample II), we got 540 new velocities and HI profiles, corresponding to a mean detec- 3. HI detection rate tion rate of 61%. The investigation of the HI line detection rate is of great However, it is important to make a more detailed interest with regard to the HI-completeness of Tully- study: we could suspect, for example, that very inclined Fisher catalogues. In particular, this HI-completeness is objects (edge-on spirals), which have generally a rather required to insure against biases by using the inverse re- wide profile for a low signal to noise ratio, are less eas- lation (log Vm = aM + b; see Ekholm & Teerikorpi 1997), ily detectable than face-on objects. Early type spirals, or the TF-21 relation (MHI = a log Vm + b,whereMHI is which contain less neutral hydrogen gas than late type the HI mass); note that the latter relies exclusively (ex- spirals, are also expected to be less detectable. Finally, cept for the inclination of the objects) upon parameters for galaxies having a known radial velocity, it is interest- derived from the HI profile of a galaxy (Dole & Theureau ing to study the detection rate with increasing redshift. 1997). Figures 1a (resp. 2a), 1b (resp. 2b), and 1c show the detec- Concerning the detection rate, it is pertinent to ex- tion rate (broken line) respectively as a function of incli- amine separately the observations for which the radial ve- nation, morphological type, and radial velocity for Sample locity is known from the literature, and those which first I (resp. Sample II). The histogram on the bottom of each require a radio velocity search. 1821 galaxies of our pro- panel represents the ratio of the number of objects rel- gramme (hereafter Sample I) had already a published ra- ative to the total sample size (samples I or II). For this dial velocity, and 1572 of these have been successfully ob- ratio n/ntot, in Figs. 1a, 1c, and 2a, the scale of the actual served at Nan¸cay. This proportion corresponds to a mean vertical axis must be divided by 10. G. Theureau et al.: Kinematics of the local universe. VII. 335 (Cols. 7 and 9) have been corrected to the optical velocity scale. According to Fouqu´e et al. (1990), the mean mea- surement error is equal to 3 · σ(V20)and2·σ(V20)for the 20% and 50% widths, respectively. We give in column 11 the derived value of the logarithm of the maximum of circular velocity log Vm. It has been calculated as follows. The widths W20 and W50 are first corrected for resolution effect: Wl,R=0 = Wl,R +(0.014 · l − 0.83) for l =20andl= 50 (Bottinelli et al. 1990), and further corrected for internal velocity dispersion: 2 2 2 2 2 2 −Ws /wr −Ws /wr Wc = W + wt (1 − 2e ) − 2W · wt(1 − e ) where wt =2σz·k(l), assuming an isotropic distribu- −1 tion of the non-circular motions σz =12kms and a nearly Gaussian velocity distribution (k(20)=1.96 and k(50)=1.13; Fouqu´e et al. 1990). Corrected W20 and W50 are finally used to calculate log Vm: Fig. 2. detection rate as a function of: a) inclination, b) Type, log V =(2logW +logW )/3 − log(2sinincl).