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The ISOPHOT 170 μm Serendipity Survey II. The catalog of optically identified galaxies%
The ISOPHOT Serendipity Sky Survey strip-scanning measurements covering≈15% of the far-infrared (FIR) sky at 170 μm were searched forcompact sources associated with optically identified galaxies. CompactSerendipity Survey sources with a high signal-to-noise ratio in at leasttwo ISOPHOT C200 detector pixels were selected that have a positionalassociation with a galaxy identification in the NED and/or Simbaddatabases and a galaxy counterpart visible on the Digitized Sky Surveyplates. A catalog with 170 μm fluxes for more than 1900 galaxies hasbeen established, 200 of which were measured several times. The faintest170 μm fluxes reach values just below 0.5 Jy, while the brightest,already somewhat extended galaxies have fluxes up to ≈600 Jy. For thevast majority of listed galaxies, the 170 μm fluxes were measured forthe first time. While most of the galaxies are spirals, about 70 of thesources are classified as ellipticals or lenticulars. This is the onlycurrently available large-scale galaxy catalog containing a sufficientnumber of sources with 170 μm fluxes to allow further statisticalstudies of various FIR properties.Based on observations with ISO, an ESA project with instruments fundedby ESA Member States (especially the PI countries: France, Germany, TheNetherlands and the UK) and with the participation of ISAS and NASA.Members of the Consortium on the ISOPHOT Serendipity Survey (CISS) areMPIA Heidelberg, ESA ISO SOC Villafranca, AIP Potsdam, IPAC Pasadena,Imperial College London.Full Table 4 and Table 6 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr ( or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/422/39

Mass-to-light ratios from the fundamental plane of spiral galaxy discs
The best-fitting two-dimensional plane within the three-dimensionalspace of spiral galaxy disc observables (rotational velocityvrot, central disc surface brightnessμ0=-2.5logI0 and disc scalelength h) has beenconstructed. Applying the three-dimensional bisector method ofregression analysis to a sample of ~100 spiral galaxy discs that spanmore than 4magarcsec-2 in central disc surface brightnessyields vrot\proptoI0.50\pm0.050\,h0.77\pm 0.07 (B band)and vrot\proptoI0.43\pm0.040\,h0.69\pm 0.07 (R band).Contrary to popular belief, these results suggest that in the B band,the dynamical mass-to-light ratio (within four disc scalelengths) islargely independent of the surface brightness, varying as I0.00\pm0.100\,h0.54\pm 0.14. Consistentresults were obtained when the range of the analysis was truncated byexcluding the low-surface-brightness galaxies. Previous claims thatM/LBvaries withI-1/20,Bareshown to be misleading and/or caused by galaxy selection effects - notall low-surface-brightness disc galaxies are dark matter dominated. Thesituation is, however, different in the near-infrared whereLK'~v4 and M/LK' is shown to vary asI-1/20,K\prime. Theoretical studies ofspiral galaxy discs should therefore not assume a constant M/L ratiowithin any given passband. The B-band dynamical mass-to-light ratio(within four disc scalelengths) has no obvious correlation with (B-R)disc colour, while in the K' band it varies as -1.25+/-0.28(B-R).Combining the present observational data with recent galaxy modelpredictions implies that the logarithm of the stellar-to-dynamical massratio is not a constant value, but increases as discs become redder,varying as 1.70+/-0.28(B-R).

An Investigation into the Prominence of Spiral Galaxy Bulges
From a diameter-limited sample of 86 low-inclination (face-on) spiralgalaxies, the bulge-to-disk size and luminosity ratios and otherquantitative measurements for the prominence of the bulge are derived.The bulge and disk parameters have been estimated using aseeing-convolved Sérsic r1/n bulge and aseeing-convolved exponential disk that were fitted to the optical (B, R,and I) and near-infrared (K) galaxy light profiles. In general,early-type spiral galaxy bulges have Sérsic values of n>1, andlate-type spiral galaxy bulges have values of n<1. In the B band,only eight galaxies have a bulge shape parameter n consistent with theexponential value 1, and only five galaxies do in the K band. Use of theexponential bulge model is shown to restrict the range ofre/h and B/D values by more than a factor of 2. Applicationof the r1/n bulge models, unlike exponential bulge models,results in a larger mean re/h ratio for the early-type spiralgalaxies than for the late-type spiral galaxies, although this result isshown not to be statistically significant. The mean B/D luminosity ratiois, however, significantly larger (>3 σ) for the early-typespirals than for the late-type spirals. Two new parameters areintroduced to measure the prominence of the bulge. The first is thedifference between the central surface brightness of the galaxy and thesurface brightness level at which the bulge and disk contribute equally.The other test uses the radius at which the contribution from the diskand bulge light are equal, normalized for the effect of intrinsicallydifferent galaxy sizes. Both of these parameters reveal that theearly-type spiral galaxies ``appear'' to have significantly (more than 2σ in all passbands) bigger and brighter bulges than late-typespiral galaxies. This apparent contradiction with the re/hvalues can be explained with an iceberg-like scenario, in which thebulges in late-type spiral galaxies are relatively submerged in theirdisk. This can be achieved by varying the relative stellar density whilemaintaining the same effective bulge-to-disk ratio. The B/D luminosityratio and the concentration index C31, in agreement with paststudies, are positively correlated and decrease as one moves along thespiral Hubble sequence toward later spiral galaxy types, although forgalaxies with large extended bulges the concentration index no longertraces the B/D luminosity ratio in a one-to-one fashion. A strong(Spearman's rank-order correlation coefficient, rs=0.80) andhighly significant positive correlation exists between the shape, n, ofthe bulge light profile and the bulge-to-disk luminosity ratio. Theabsolute bulge magnitude-logn diagram is used as a diagnostic tool forcomparative studies with dwarf elliptical and ordinary ellipticalgalaxies. At least in the B band these objects occupy distinctlydifferent regions of this parameter space. While the dwarf ellipticalgalaxies appear to be the faint extension to the brighter ellipticalgalaxies, the bulges of spiral galaxies do not; for a given luminositythey have a noticeably smaller shape parameter and hence a more dramaticdecline of stellar density at large radii.

Supernova Type Ia Luminosities, Their Dependence on Second Parameters, and the Value of H0
A sample of 35 Type Ia supernovae (SNe Ia) with good to excellentphotometry in B and V, minimum internal absorption, and1200

Arcsecond Positions of UGC Galaxies
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.

Total magnitude, radius, colour indices, colour gradients and photometric type of galaxies
We present a catalogue of aperture photometry of galaxies, in UBVRI,assembled from three different origins: (i) an update of the catalogueof Buta et al. (1995) (ii) published photometric profiles and (iii)aperture photometry performed on CCD images. We explored different setsof growth curves to fit these data: (i) The Sersic law, (ii) The net ofgrowth curves used for the preparation of the RC3 and (iii) A linearinterpolation between the de Vaucouleurs (r(1/4) ) and exponential laws.Finally we adopted the latter solution. Fitting these growth curves, wederive (1) the total magnitude, (2) the effective radius, (3) the colourindices and (4) gradients and (5) the photometric type of 5169 galaxies.The photometric type is defined to statistically match the revisedmorphologic type and parametrizes the shape of the growth curve. It iscoded from -9, for very concentrated galaxies, to +10, for diffusegalaxies. Based in part on observations collected at the Haute-ProvenceObservatory.

HIPPARCOS calibration of the peak brightness of four SNe IA and the value of H_0
HIPPARCOS geometrical parallaxes allowed us to calibrate the CepheidPeriod-Luminosity relation and to compute the true distance moduli of 17galaxies. Among these 17 galaxies, we selected those which generatedtype Ia Supernovae (SNe Ia). We found NGC 5253, parent galaxy of 1895Band 1972E, IC 4182 and NGC 4536 parents of 1937C and 1981B,respectively. We used the available B-band photometry to determine thepeak brightness of these four SNe Ia. We obtained = -19.65 +/- 0.09. Then, we built a sample of 57SNe Ia in order to plot the Hubble diagram and determine its zero-point.Our result (ZPB = -3.16 +/- 0.10) is in agreement with otherdeterminations and allows us to derive the following Hubble constant:H0 = 50 +/- 3 (internal) km.s(-1}.Mpc({-1)) .

Gas Mass Fractions and the Evolution of Spiral Galaxies
We show that the gas mass fraction of spiral galaxies is stronglycorrelated with luminosity and surface brightness. It is not correlatedwith linear size. Gas fraction varies with luminosity and surfacebrightness at the same rate, indicating evolution at fixed size. Dimgalaxies are clearly less evolved than bright ones, having consumed only~ \frac {1}{2} of their gas. This resolves the gas consumption paradox,since there exist many galaxies with large gas reservoirs. Thesegas-rich galaxies must have formed the bulk of their stellar populationsin the last half of a Hubble time. The existence of such immaturegalaxies at z = 0 indicates that either galaxy formation is a lengthy oreven ongoing process, or the onset of significant star formation can bedelayed for arbitrary periods in tenuous gas disks.

Constraining the Ages of Supernova Progenitors. I. Supernovae and Spiral Arms
We present the first results of a three-part study of supernova (SN)ages using positional age indicators in spiral galaxies. We havemeasured the positions of 90 Spectroscopically identified Type Ia andType II SNs (SNs Ia and SNs II) relative to spiral arms in their hostgalaxies, making a special effort to reduce inhomogeneity in the processof arm tracing for different galaxies. We find that SNs II are moretightly concentrated to the arms than SNs Ia, but both kinds of SNsoccur closer to arms than a random disk population. However, whencompared with the distribution of V and I light relative to the arms,the SNs Ia are no more tightly concentrated than the general stellarpopulation. This indicates that SNs Ia occur in a population old enoughto have diffused away from their formation regions.

Explosion Models for Type IA Supernovae: A Comparison with Observed Light Curves, Distances, H 0, and Q 0
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996ApJ...457..500H&db_key=AST

Photoelectric UBV Photometry of 179 Bright Galaxies
This paper presents photoelectric UBV multiaperture photometry of 179bright galaxies that was used to compute total magnitudes and colorindices published in the Third Reference Catalog of Bright Galaxies(RC3). The observations were made at the McDonald Observatory from 1983December to 1986 September with an Amperex 56-DVP photometer attached tothe 0.76 and 0.91 m telescopes. The observations can also be used tocalibrate CCD images.

Photoelectric UBV Photometry of Galaxies in the Clusters Pegasus I, Pegasus II, Abell 262, Abell 1367, and Abell 2197-9
This paper presents photoelectric UBV multiaperture photometry of 144galaxies, 139 of which are associated with six nearby bright clusters.The observations were made at the McDonald Observatory from 1986September to 1987 November and were part of the production of the ThirdReference Catalogue of Bright Galaxies (RC3). The observations were usedto compute total magnitudes and color indices published in RC3. Theobservations can also be used to calibrate CCD images.

Near-infrared and optical broadband surface photometry of 86 face-on disk dominated galaxies. II. A two-dimensional method to determine bulge and disk parameters.
In this Paper I present a new two-dimensional decomposition technique,which models the surface photometry of a galaxy with an exponentiallight profile for both bulge and disk and, when necessary, with aFreeman bar. The new technique was tested for systematic errors on bothartificial and real data and compared with widely used one-dimensionaldecomposition techniques, where the luminosity profile of the galaxy isused. The comparisons indicate that a decomposition of thetwo-dimensional image of the galaxy with an exponential light profilefor both bulge and disk yields the most reproducible and representativebulge and disk parameters. An extensive error analysis was made todetermine the reliability of the model parameters. If the model with anexponential bulge profile is a reasonable description of a galaxy, themaximum errors in the derived model parameters are of order 20%. Theuncertainties in the model parameters will increase, if the exponentialbulge function is replaced by other often used bulge functions as the deVaucouleurs law. All decomposition methods were applied to the opticaland near-infrared data set presented by de Jong & van der Kruit(1994), which comprises 86 galaxies in six passbands.

An image database. II. Catalogue between δ=-30deg and δ=70deg.
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.

The Hubble Diagram for Supernovae of Type Ia. II. The Effect on the Hubble Constant of a Correlation between Absolute Magnitude and Light Decay Rate
New Hubble diagrams in B and V are derived for supernovae of type Ibased on light curves from the archive literature plus 13 new lightcurves with superior modern photometry observed in the CerroTololo/University of Chile program (Hamuy et al, 1995). The sample isrestricted to SNe Ia whose light curves are defined by photometrybeginning 5 days or less after maximum light and with (B - V)max <0.5 mag. Supernovae of known type Ib or Ic are also excluded. Theresulting Hubble diagrams, extending to redshifts of 30,00 km s^- 1^,have dispersions in absolute magnitude of 0.34 mag in B and 0.33 mag inV, confirming that spectroscopically "normal" (Branch et al. 1993) SNeIa are among the best standard candles known. A solution for the slopeof the Hubble diagram gives n(B) = 0.977 +/- 0.025 and n(V) = 1.020 +/-0.024 for the exponent in ν~D^n^, proving linearity of the expansionfield to a high level. The residuals in magnitude from the ridge line ofthe Hubble diagram are compared with the light decay rate during thefirst 15 days to test the correlation between the two suggested byPskovskii and by Phillips. The strongest possible correlation using theextant data has a slope 3 times smaller than that derived by Phillips,and 2 times smaller than suggested by Hamuy et al., leading to adecrease of less than 10% in the distance scale based on the present(1995) SNe Ia calibration by means of three supernovae whose distancesare known from Cepheids in their parent galaxies. Applying the maximumpossible correction to M(max) for a Psko'vskii- Phillips effect wouldgive Hubble constants of H_0_(B)<= 54 +/- 4 km s^-1^ Mpc^-1^, andH_0_(V) <= 59 +/- 4 km s^-1^ Mpc^-1^, where the errors are internal.It is argued that the absence of measurable bias effects in the Hubblediagrams shows that the three local (nearest) SNe Ia presentlycalibrated via Cepheid distances cannot all be overluminous relative tothe average of more distant SNe. If they are underluminous, which mustbe the case by the statistics of the Malmquist effect if the largedispersion in M(max) for SNe Ia claimed by Hamuy et al. applies to thecalibrators, then the value of H_0_ = 52 km s^-1^ Mpc^-1^ given by Sahaet al. is an upper limit to the Hubble constant.

The blue anbd visual absolute magnitude distributions of Type IA supernovae
Tully-Fisher (TF), surface brightness fluctuation (SBF), and Hubble lawdistances to the parent galaxies of Type Ia supernovae (SNs Ia) are usedin order to study the SN Ia blue and visual peak absolute magnitude(MB and MV) distributions. We propose twoobjective cuts, each of which produces a subsample with small intrinsicdispersion in M. One cut, which can be applied to either band,distinguishes between a subsample of bright events and a smallersubsample of dim events, some of which were extinquished in the parentgalaxy and some of which were intrinsically subluminous. The brightevents are found to be distributed with an observed dispersions of 0.3less than or approximately = Sigmaobs less than orapproximately = 0.4 about a mean absolut magnitude (M-barB orM-barV). Each of the dim SNs was spectroscopically peculiarand/or had a red B-V color; this motivates the adoption of analternative cut that is based on B-V rather than on M. To wit, SNs Iathat are both known to have -0.25 less than B-V less than + 0.25 and notknown to be spectroscopically peculiar show observational dispersion ofonly Sigmaobs(MB) =Sigmaobs(MV) = 0.3. Because characteristicsobservational errors produce Sigmaerr(M) greater than 0.2,theintrinsic dispersion among such SNs Ia is Sigmaint(M) lessthan or approximately = 0.2. The small observational dispersionindicates that SNs Ia, the TF relation, and SBFs all good relativedistances to those galaxies that produce SNs Ia. The conflict betweenthose who use SNs Ia in order to determine the value of the Hubbleconstant (H0) and those who use TF and SBF distances todetermine H0 results from discrepant calibrations.

Total and effective colors of 501 galaxies in the Cousins VRI photometric system
Total color indices (V-R)T, (V-I)T and effectivecolor indices (V-R)e, (V-I)e in the Cousins VRIphotometric system are presented for 501 mostly normal galaxies. Thecolors are computed using a procedure outlined in the Third ReferenceCatalogue of Bright Galaxies (RC3) whereby standard color curvesapproximated by Laplace-Gauss integrals are fitted to observedphotoelectric multiaperture photometry. 11 sources of such photometrywere used for our analysis, each source being assigned an appropriateweight according to a rigorous analysis of residuals of the data fromthe best-fitting standard color curves. Together with the integrated B-Vand U-B colors provided in RC3, our analysis widens the range ofwavelength of homogeneously defined colors of normal galaxies of allHubble types. We present color-color and color-type relations that canbe modeled to understand the star formation history of galaxies.

Integrated photoelectric magnitudes and color indices of bright galaxies in the Johnson UBV system
The photoelectric total magnitudes and color indices published in theThird Reference Catalogue of Bright Galaxies (RC3) are based on ananalysis of approximately equals 26,000 B, 25,000 B-V, and 17,000 U-Bmultiaperture measurements available up to mid 1987 from nearly 350sources. This paper provides the full details of the analysis andestimates of internal and external errors in the parameters. Thederivation of the parameters is based on techniques described by theVaucouleurs & Corwin (1977) whereby photoelectric multiaperture dataare fitted by mean Hubble-type-dependent curves which describe theintegral of the B-band flux and the typical B-V and U-B integrated colorgradients. A sophisticated analysis of the residuals of thesemeasurements from the curves was made to allow for the random andsystematic errors that effect such data. The result is a homogeneous setof total magnitudes BTA total colors(B-V)T and (U-B)T, and effective colors(B-V)e and (U-B)e for more than 3000 brightgalaxies in RC3.

Distribution of supernovae relative to spiral arms and H II regions
We have studied the association of supernovae in spiral galaxies withsites of recent stars formation -- sprial arms and H II regions. It isshown that supernovae (SNe) of Types Ia, Ib, and II exhibitconcentration to spiral arms and their distributions over the distanceto the nearest spiral arm do not differ significantly. This result isconfirmed by a Kolmogorov-Smirnov test comparison with the distancedistributions, expected if SNe are distributed randomly inside the modelgalaxy. SNe of types Ib and II show a strong concentration towards H IIregions, while distribution of SNe Ia can be explained by chancesuperposition. All studied distributions of SNe Ib and II show strikingsimilarity, which suggests that their progenitors are massive stars withsimilar ages and initial masses. The association of SNe Ia with spiralarms suggests that their progenitors in spiral galaxies are likely to beintermediate mass stars.

Near-infrared and optical broadband surface photometry of 86 face-on disk dominated galaxies. I. Selection, observations and data reduction.
We present accurate surface photometry in the B, V, R, I, H and Kpassbands of 86 spiral galaxies. The galaxies in this statisticallycomplete sample of undisturbed spirals were selected from the UGC tohave minimum diameters of 2' and minor over major axis ratios largerthan 0.625. This sample has been selected in such a way that it can beused to represent a volume limited sample. The observation and reductiontechniques are described in detail, especially the not often useddriftscan technique for CCDs and the relatively new techniques usingnear-infrared (near-IR) arrays. For each galaxy we present radialprofiles of surface brightness. Using these profiles we calculated theintegrated magnitudes of the galaxies in the different passbands. Weperformed internal and external consistency checks for the magnitudes aswell as the luminosity profiles. The internal consistency is well withinthe estimated errors. Comparisons with other authors indicate thatmeasurements from photographic plates can show large deviations in thezero-point magnitude. Our surface brightness profiles agree within theerrors with other CCD measurements. The comparison of integratedmagnitudes shows a large scatter, but a consistent zero-point. Thesemeasurements will be used in a series of forthcoming papers to discusscentral surface brightnesses, scalelengths, colors and color gradientsof disks of spiral galaxies.

A comparison of calculated and observed monochromatic Type IA supernova light curves
The calculated monochromatic (B and V) light curves of a set of Type Iasupernova models are compared with the observed monochromatic lightcurves of 13 Type Ia supernovae (SNIa). The set consists of 11 Type Iasupernova models including deflagrations, detonations, delayeddetonations, pulsating delayed detonations and tamped detonations. Thetheoretical light curves have been calculated using our recentlydeveloped light curve model. The model incorporates a detailed equationof state with an elaborate treatment of the ionization balance, animplicit grey Local Thermodynamic Equilibrium (LTE) radiation transportscheme based on the moment equations, a total energy equation for thegas and the radiation field, expansion opacities, and a Monte Carlogamma-ray deposition scheme. To evolve the structure of the underlyingexplosion models homologous expansion is assumed. We find that fastrising light curves (e.g., SN 1972E, SN 1981B and SN 1986G) can bereproduced best by delayed detonation models, and that slowly rising(tmax greater than or approximately equal to 17 days) lightcurves (e.g., SN 1984A and SN 1990N) cannot be reproduced by standarddetonation, deflagration or delayed detonation models. In order toobtain an acceptable agreement with observations for slowly rising lightcurves explosion models are required where the C/O white dwarf issurrounded by an unburnt extended envelope of typically 0.2 to 0.4 solarmass. Our interpretation of the light curves is also favored from theexpansion velocities observed in the spectra of the slowly rising SNIa.Based on a comparison of theoretical light curves and observationaldata, the distances of the parent galaxies have been determined. We showthat SNeIa allow for a measurement of the value of the Hubble constantprovided individual fits are used and if they are located at distanceslarger than 15 Mpc, because only then they are in the 'Hubble' flow.Taking this restriction into account a Hubble constant of H = 66 +/- 10km/(secMpc) can be derived within a 2 sigma error.

The Hubble diagram in V for supernovae of Type IA and the value of H(0) therefrom
The Hubble diagram for Type I supernovae is derived in V and issummarized from the literature in B and in m(pg). The ridge lineequation of the diagram in V and the calibration of the absolutemagnitudes at maximum are presented. The intrinsic (B - V) color at Bmaximum light is 0.09 +/- 0.04 mag. The Virgo Cluster distance isderived and found to be 23.9 +/- 2.4 Mpc. This Virgo distance gives thecosmic value of the Hubble constant to be H(0) = 47 +/- 5 km/sec perMpc.

Type IA supernovae as standard candles
The distribution of absolute blue magnitudes among Type Ia supernovae(SNs Ia) is studied. Supernovae were used with well determined apparentmagnitudes at maximum light and parent galaxies with relative distancesdetermined by the Tully-Fisher or Dn - sigma techniques. The meanabsolute blue magnitude is given and the observational dispersion isonly sigma(MB) 0.36, comparable to the expected combined errors indistance, apparent magnitude, and extinction. The mean (B-V) color atmaximum light is 0.03 +/- 0.04, with a dispersion sigma(B-V) = 0.20. TheCepheid-based distance to IC 4182, the parent galaxy of the normal andunextinguished Type Ia SN 1937C, leads to a Hubble constant of H(0) + 51+/- 12 km/s Mpc. The existence of a few SNs Ia that appear to have beenreddened and dimmed by dust in their parent galaxies does not seriouslycompromise the use of SNs Ia as distance indicators.

The Local Group Motion Towards Virgo and the Microwave Background
The peculiar motion of the Local Group is determined from 15 clusterswhose relative distances are known with minimum bias. The resultinglocal motion is 745 +/- 106 kms^-1^ towards l = 273^deg^, b = 3^deg^.This 7σ signal is in perfect statistical agreement with the motioninferred from the dipole of the cosmic microwave background. The mediandistance of 6400 km s^-1^ of the 15 clusters sets an upper limit to thecomoving volume. - The three-dimensional peculiar motions of theclusters become 587 km s^-1^, if allowance is made for a 5 percent errorof the cluster distances. The value compares well with the 489 km s^-1^motion of the Virgo complex with respect to the cosmic microwavebackground. - The data imply a local slow-down of the expansion fielddue to the Virgo cluster of v_VC_ = 239 +/- 40 km s^-1^. An almostidentical value, i.e. v_VC_ = 233 +/- 44 km s^-1^, is independentlydetermined using the relative distances of the Virgo, UMa, and Fornaxclusters and of eight nearby supernovae of type Ia. - These results donot require the adoption of any zero-point of the extragalactic distancescale.

Groups of galaxies within 80 Mpc. II - The catalogue of groups and group members
This paper gives a catalog of the groups and associations obtained bymeans of a revised hierarchical algorithm applied to a sample of 4143galaxies with diameters larger than 100 arcsec and redshifts smallerthan 6000 km/s. The 264 groups of galaxies obtained in this way (andwhich contain at least three sample galaxies) are listed, with the looseassociations surrounding them and the individual members of eachaggregate as well; moreover, the location of every entity among 13regions corresponding roughly to superclusters is specified. Finally,1729 galaxies belong to the groups, and 466 to the associations, i.e.,the total fraction of galaxies within the various aggregates amounts to53 percent.

Supernova studies. I - A catalogue of magnitude observations of supernovae I
A catalog of photometric observations (UBV or pg) of 81 supernovae oftype I is presented. Only supernovae with multiple data were included.

The Asiago Supernova Catalogue
A Catalogue of Supernovae (SNe) is presented which tabulates the maindata relative to all extragalactic SNe discovered up to 1988 December31, and to their parent galaxies. In total 661 SNe are listed of which267 are classified. For an easier consultation, two lists are givenwhere the SNe are ordered chronologically and by Right Ascension,respectively. The overall distribution of classified supernovae over themorphological types of their parent galaxies is also presented in asummary table.

The peculiar velocity of the Local Group. II - H I observations of SC galaxies
H I observations of a sample of 163 Sc galaxies have been obtained usingthe Mk IA and Mk II Jodrell Bank radio telescopes. In the presentanalysis, the overall rms error in redshift determination is 5 km/s andthe rms error in velocity width determination is 10 km/s. The resultssuggest that Sc galaxies have high internal obscuration and may beoptically thicker in blue light than earlier-type spirals. An orthogonalthree-dimensional classification system based on three uncorrelatedparameters related to linear diameter, quiescent star-formation rate,and embedded starburst-type activity is shown to account for the globalproperties of Sc galaxies with an accuracy close to the limit ofmeasurement error.

Arm classifications for spiral galaxies
The spiral arm classes of 762 galaxies are tabulated; 636 galaxies withlow inclinations and radii larger than 1 arcmin were classified on thebasis of their blue images on the Palomar Observatory Sky Survey (POSS),76 SA galaxies in the group catalog of Geller and Huchra were alsoclassified from the POSS, and 253 galaxies in high-resolution atlaseswere classified from their atlas photographs. This spiral armclassification system was previously shown to correlate with thepresence of density waves, and galaxies with such waves were shown tooccur primarily in the densest galactic groups. The present sampleindicates, in addition, that grand design galaxies (i.e., those whichtend to contain prominent density wave modes) are physically larger thanflocculent galaxies (which do not contain such prominent modes) by afactor of about 1.5. A larger group sample confirms the previous resultthat grand design galaxies are preferentially in dense groups.

Light and colour curves of type I and II supernovae.
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Right ascension:23h08m57.20s
Aparent dimensions:1.66′ × 1.479′

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NGC 2000.0NGC 7495

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