We present an all-sky catalog of 451 nearby galaxies, each having an individual distance estimate D P 10 Mpc or a radial velocity V LG < 550 km s À1 . The catalog contains data on basic optical and H i properties of the galaxies, in particular, their diameters, absolute magnitudes, morphological types, circumnuclear region types, optical and H i surface brightnesses, rotational velocities, and indicative mass-to-luminosity and H i massto-luminosity ratios, as well as a so-called tidal index, which quantifies the galaxy environment. We expect the catalog completeness to be roughly 70%-80% within 8 Mpc. About 85% of the Local Volume population are dwarf (dIr, dIm, and dSph) galaxies with M B > À17:0, which contribute about 4% to the local luminosity density, and roughly 10%-15% to the local H i mass density. The H i mass-to-luminosity and the H i mass-tototal (indicative) mass ratios increase systematically from giant galaxies toward dwarfs, reaching maximum values about 5 in solar units for the most tiny objects. For the Local Volume disklike galaxies, their H i masses and angular momentum follow Zasov's linear relation, expected for rotating gaseous disks being near the threshold of gravitational instability, favorable for active star formation. We found that the mean local luminosity density exceeds 1.7-2.0 times the global density, in spite of the presence of the Tully void and the absence of rich clusters in the Local Volume. The mean local H i density is 1.4 times its ''global'' value derived from the H i Parkes Sky Survey. However, the mean local baryon density b (<8 Mpc) ¼ 2:3% consists of only a half of the global baryon density, b ¼ (4:7 AE 0:6)% (Spergel et al., published in 2003). The mean-square pairwise difference of radial velocities is about 100 km s À1 for spatial separations within 1 Mpc, increasing to $300 km s À1 on a scale of $3 Mpc. We also calculated the integral area of the sky occupied by the neighboring galaxies. Assuming the H i size of spiral and irregular galaxies to be 2.5 times their standard optical diameter and ignoring any evolution effect, we obtain the expected number of the line-of-sight intersections with the H i galaxy images to be dn=dz $ 0:4, which does not contradict the observed number of absorptions in QSO spectra.

We present the compilation catalogue of redshift-independent distances included in the HyperLEDA database. It is actively maintained to be up-to-date, and the current version counts 6640 distance measurements for 2335 galaxies compiled from 430 published articles. Each individual series is recalibrated onto a common distance scale based on a carefully selected set of high-quality measurements.This information together with data on H i line width, central velocity dispersion, magnitudes, diameters, and redshift is used to derive a homogeneous distance estimate and physical properties of galaxies, such as their absolute magnitudes and intrinsic size.

We present an all-sky catalog of 869 nearby galaxies, having individual distance estimates within 11 Mpc or corrected radial velocities V LG < 600 km s −1 .The catalog is a renewed and expanded version of the "Catalog of Neighboring Galaxies" by Karachentsev et al. (2004). It collects data on the following observables for the galaxies: angular diameters, apparent magnitudes in F UV -, B-, and K s -bands, Hα and HI fluxes, morphological types, HI-line widths, radial velocities and distance estimates. In this Local Volume (LV) sample 108 dwarf galaxies remain to be still without measured radial velocities.The catalog yields also calculated global galaxy parameters: linear Holmberg diameter, absolute B-magnitude, surface brightness, HI-mass, stellar mass estimated via K-band luminosity, HI rotational velocity corrected for galaxy inclination, indicative mass within the Holmberg radius, and three kinds of "tidal index", which quantify the local density environment. The catalog is supplemented with the data based on the local galaxies (http://www.sao.ru/lv/lvgdb), which presents their optical and available Hα images, as well as other service.We briefly discuss the Hubble flow within the LV, and different scaling relations that characterize galaxy structure and global star formation in them. We also trace the behavior of the mean stellar mass density, HI-mass density and star formation rate density within the considered volume.

Cosmicflows-2 is a compilation of distances and peculiar velocities for over 8000 galaxies. Numerically the largest contributions come from the luminosity-linewidth correlation for spirals, the TFR, and the related Fundamental Plane relation for E/S0 systems, but over 1000 distances are contributed by methods that provide more accurate individual distances: Cepheid, Tip of the Red Giant Branch, Surface Brightness Fluctuation, SNIa, and several miscellaneous but accurate procedures. Our collaboration is making important contributions to two of these inputs: Tip of the Red Giant Branch and TFR. A large body of new distance material is presented. In addition, an effort is made to assure that all the contributions, our own and those from the literature, are on the same scale. Overall, the distances are found to be compatible with a Hubble Constant H 0 = 74.4 ± 3.0 km s −1 Mpc −1 . The great interest going forward with this data set will be with velocity field studies. Cosmicflows-2 is characterized by a great density and high accuracy of distance measures locally, falling to sparse and coarse sampling extending to z = 0.1.

The luminosity of the tip of the red giant branch (TRGB) provides an excellent measure of galaxy distances and is easily determined in the resolved images of nearby galaxies observed with Hubble Space Telescope. There is now a large amount of archival data that are relevant to the TRGB methodology and offer comparisons with other distance estimators. Zero-point issues related to the TRGB distance scale are reviewed in this paper. Consideration is given to the metallicity dependence of the TRGB, the transformations between HST flight systems and Johnson-Cousins photometry, the absolute magnitude scale based on horizontal branch measurements, and the effects of reddening. The zero point of the TRGB is established with a statistical accuracy of 1%, modulo the uncertainty in the magnitude of the horizontal branch, with a typical rms uncertainty of 3% in individual galaxy distances at high Galactic latitude. The zero point is consistent with the Cepheid periodYluminosity relation scale but invites reconsideration of the claimed metallicity dependence with that method. The maser distance to NGC 4258 is consistent with TRGB but presently has lower accuracy.

A database can be accessed on the Web at http://edd.ifa.hawaii.edu that was developed to promote access to information related to galaxy distances. The database has three functional components. First, tables from many literature sources have been gathered and enhanced with links through a distinct galaxy naming convention. Second, comparisons of results both at the levels of parameters and of techniques have begun and are continuing, leading to increasing homogeneity and consistency of distance measurements. Third, new material is presented arising from ongoing observational programs at the University of Hawaii 2.2 m telescope, radio telescopes at Green Bank, Arecibo, and Parkes and with the Hubble Space Telescope. This new observational material is made available in tandem with related material drawn from archives and passed through common analysis pipelines.

We present HST/ACS images and color-magnitude diagrams for 24 nearby galaxies in and near the constellation of Centaurus with radial velocities V LG < 550 km s −1 . Distances are determined based on the luminosities of stars at the tip of the red giant branch that range from 3.0 Mpc to 6.5 Mpc. The galaxies are concentrated in two spatially separated groups around Cen A (NGC 5128) and M 83 (NGC 5236). The Cen A group itself has a mean distance of 3.76±0.05 Mpc, a velocity dispersion of 136 kms −1 , a mean harmonic radius of 192 kpc, and an estimated orbital/virial mass of (6.4 − 8.1) · 10 12 M ⊙ . This elliptical dominated group is found to have a relatively high mass-to-light ratio: M/L B = 125 M ⊙ /L ⊙ . For the M 83 group we derived a mean distance of 4.79±0.10 Mpc, a velocity dispersion of 61 km s −1 , a mean harmonic radius of 89 kpc, and estimated orbital/virial mass of (0.8 − 0.9) · 10 12 M ⊙ . This spiral dominated group is found to have a relatively low M/L B = 34 M ⊙ /L ⊙ . The radius of the zero-velocity surface around Cen A lies at R 0 = 1.40 ± 0.11 Mpc. implying a total mass within R 0 of M T = (6.0 ± 1.4) · 10 12 M ⊙ . This value is in good agreement with the Cen A virial/orbital mass estimates and provides confirmation of the relatively high M/L B of this elliptical-dominated group. The centroids of both the groups, as well as surrounding field galaxies, have very small peculiar velocities, < 25 km s −1 , with respect to the local Hubble flow with H 0 = 68 km s −1 Mpc −1 .

We present an all-sky catalogue of 395 nearby galaxy groups revealed in the Local Supercluster and its surroundings. The groups and their associations are identified among 10 914 galaxies at |b| > 15 • with radial velocities V LG < 3500 km s −1 . Our group-finding algorithm requires the group members to be located inside their zero-velocity surface. Hereby, we assume that individual galaxy masses are proportional to their total K-band luminosities,The sample of our groups, where each group has n ≥ 4 members, is characterized by the following medians: mean projected radius R = 268 kpc, radial velocity dispersion σ V = 74 km s −1 , K-band luminosity L K = 1.2 × 10 11 L , virial and projected masses M vir = 2.4 × 10 12 and M p = 3.3 × 10 12 M , respectively. Accounting for measurement error reduces the median masses by 30 per cent. For 97 per cent of identified groups the crossing time does not exceed the cosmic time, 13.7 Gyr, with the median at 3.8 Gyr.We examine different properties of the groups, in particular of the known nearby groups and clusters in Virgo and Fornax. About a quarter of our groups can be classified as fossil groups where the dominant galaxy is at least 10 times brighter than the other group members.In total, our algorithm identifies 54 per cent of galaxies to be members of groups. Together with triple systems and pairs they gather 82 per cent of the K-band light in the local Universe. We have obtained the local value of matter density to be m = 0.08 ± 0.02 within a distance of ∼40 Mpc assuming H 0 = 73 km s −1 Mpc −1 . It is significantly smaller than the cosmic value, 0.28, in the standard CDM model. The discrepancy between the global and local quantities of m may be caused by the existence of a dark matter component unrelated to the virial masses of the galaxy systems.