A catalog of Southern anomalous-velocity HI clouds at Decl. < +2 • is presented. This catalog is based on data from the HI Parkes All-Sky Survey (HIPASS) reprocessed with the minmed5 procedure (Putman et al. 2002;Putman 2000), and searched with the -2high-velocity cloud finding algorithm described by de Heij et al. (2001). The improved sensitivity (5σ: ∆T B = 0.04 K), resolution (15. ′ 5), and velocity range (−500 < V LSR < +500 km s −1 ) of the HIPASS data, results in a substantial increase in the number of individual clouds (1956, as well as 41 galaxies) compared to what was known from earlier Southern data. The method of cataloging the anomalous-velocity objects is described, and a catalog of key cloud parameters, including velocity, angular size, peak column density, total flux, position angle, and degree of isolation, is presented. The data are characterized into several classes of anomalous-velocity HI emission. Most high-velocity emission features, HVCs, have a filamentary morphology and are loosely organized into large complexes extending over tens of degrees. In addition, 179 compact and isolated anomalous-velocity objects, CHVCs, are identified based on their size and degree of isolation. 25% of the CHVCs originally classified by Braun & Burton (1999) are reclassified based on the HIPASS data. The properties of all the highvelocity emission features and only the CHVCs are investigated, and distinct similarities and differences are found. Both populations have typical HI masses of ∼ 4.5 D 2 kpc M ⊙ and have similar slopes for their column density and flux distributions. On the other hand, the CHVCs appear to be clustered and the population can be broken up into three spatially distinct groups, while the entire population of clouds is more uniformly distributed with a significant percentage aligned with the the Magellanic Stream. The median velocities are V GSR = −38 km s −1 for the CHVCs and −30 km s −1 for all of the anomalous-velocity clouds. Based on the catalog sizes, high-velocity features cover 19% of the southern sky, and CHVCs cover 1%.
The Northern HIPASS catalogue (NHICAT) is the northern extension of the HIPASS catalogue, HICAT. This extension adds the sky area between the declination (Dec.) range of +2° < δ < +25°30′ to HICAT's Dec. range of −90° < δ < +2°. HIPASS is a blind H i survey using the Parkes Radio Telescope covering 71 per cent of the sky (including this northern extension) and a heliocentric velocity range of −1280 to 12 700 km s−1. The entire Virgo Cluster region has been observed in the Northern HIPASS. The galaxy catalogue, NHICAT, contains 1002 sources with vhel > 300 km s−1. Sources with −300 < vhel < 300 km s−1 were excluded to avoid contamination by Galactic emission. In total, the entire HIPASS survey has found 5317 galaxies identified purely by their HI content. The full galaxy catalogue is publicly available at http://hipass.aus-vo.org.
The H I Parkes All Sky Survey (HIPASS) is a blind extragalactic H I 21-cm emission-line survey covering the whole southern sky from declination −90 • to +25 • . The HIPASS catalogue (HICAT), containing 4315 H I-selected galaxies from the region south of declination +2 • , is presented in Meyer et al. (Paper I). This paper describes in detail the completeness and reliability of HICAT, which are calculated from the recovery rate of synthetic sources and follow-up observations, respectively. HICAT is found to be 99 per cent complete at a peak flux of 84 mJy and an integrated flux of 9.4 Jy km s −1 . The overall reliability is 95 per cent, but rises to 99 per cent for sources with peak fluxes >58 mJy or integrated flux >8.2 Jy km s −1 . Expressions are derived for the uncertainties on the most important HICAT parameters: peak flux, integrated flux, velocity width and recessional velocity. The errors on HICAT parameters are dominated by the noise in the HIPASS data, rather than by the parametrization procedure.
We present the largest catalogue to date of optical counterparts for H i radio‐selected galaxies, HOPCAT. Of the 4315 H i radio‐detected sources from the H i Parkes All Sky Survey (HIPASS) catalogue, we find optical counterparts for 3618 (84 per cent) galaxies. Of these, 1798 (42 per cent) have confirmed optical velocities and 848 (20 per cent) are single matches without confirmed velocities. Some galaxy matches are members of galaxy groups. From these multiple galaxy matches, 714 (16 per cent) have confirmed optical velocities and a further 258 (6 per cent) galaxies are without confirmed velocities. For 481 (11 per cent), multiple galaxies are present but no single optical counterpart can be chosen and 216 (5 per cent) have no obvious optical galaxy present. Most of these ‘blank fields’ are in crowded fields along the Galactic plane or have high extinctions. Isolated ‘dark galaxy’ candidates are investigated using an extinction cut of A italicB italicj < 1 mag and the blank‐fields category. Of the 3692 galaxies with an A B j extinction <1 mag, only 13 are also blank fields. Of these, 12 are eliminated either with follow‐up Parkes observations or are in crowded fields. The remaining one has a low surface brightness optical counterpart. Hence, no isolated optically dark galaxies have been found within the limits of the HIPASS survey.
Using data from the H I Parkes All Sky Survey (HIPASS), we have searched for neutral hydrogen in galaxies in a region ∼25 × 25 deg 2 centred on NGC 1399, the nominal centre of the Fornax cluster. Within a velocity search range of 300-3700 km s −1 and to a 3σ lower flux limit of ∼40 mJy, 110 galaxies with H I emission were detected, one of which is previously uncatalogued. None of the detections has early-type morphology. Previously unknown velocities for 14 galaxies have been determined, with a further four velocity measurements being significantly dissimilar to published values. Identification of an optical counterpart is relatively unambiguous for more than ∼90 per cent of our H I galaxies. The galaxies appear to be embedded in a sheet at the cluster velocity which extends for more than 30 • across the search area. At the nominal cluster distance of ∼20 Mpc, this corresponds to an elongated structure more than 10 Mpc in extent. A velocity gradient across the structure is detected, with radial velocities increasing by ∼500 km s −1 from south-east to north-west. The clustering of galaxies evident in optical surveys is only weakly suggested in the spatial distribution of our H I detections. Of 62 H I detections within a 10 • projected radius of the cluster centre, only two are within the core region (projected radius <1 • ) and less than 30 per cent are within 3.5 • , suggesting a considerable deficit of H I-rich galaxies in the centre of the cluster. However, relative to the field, there is a 3(±1)-fold excess of H I-rich galaxies in the outer parts of the cluster where galaxies may be infalling towards the cluster for the first time.The Fornax cluster is amongst the closest and most well-studied clusters in the southern sky, providing an interesting nearby field for the study of large-scale structure (LSS), galaxy populations, dynamics and evolution in the cluster environment. Although the C 2002 RAS
The HI Parkes All-Sky Survey (HIPASS) is a blind 21-cm survey for extragalactic neutral hydrogen, covering the whole southern sky. The HIPASS Bright Galaxy Catalog (BGC; Koribalski et al. 2002) is a subset of HIPASS and contains the 1000 HI-brightest (peak flux density) galaxies. Here we present the 138 HIPASS BGC galaxies, which had no redshift measured prior to the Parkes multibeam HI surveys. Of the 138 galaxies, 87 are newly cataloged. Newly cataloged is defined as no optical (or infrared) counterpart in the NASA/IPAC Extragalactic Database. Using the Digitized Sky Survey we identify optical counterparts for almost half of the newly cataloged galaxies, which are typically of irregular or magellanic morphological type. Several HI sources appear to be associated with compact groups or pairs of galaxies rather than an individual galaxy. The majority (57) of the newly cataloged galaxies lie within ten degrees of the Galactic Plane and are missing from optical surveys due to confusion with stars or dust extinction. This sample also includes newly cataloged galaxies first discovered in the HI shallow survey of the Zone-of-Avoidance (Henning et al. 2000). The other 30 newly cataloged galaxies escaped detection due to their low surface brightness or optical compactness. Only one of these, HIPASS J0546-68, has no obvious optical counterpart as it is obscured by the Large Magellanic Cloud. We find that the newly cataloged galaxies with |b| > 10 are generally lower in HI mass and narrower in velocity width compared with the total HIPASS BGC. In contrast, newly cataloged galaxies behind the Milky Way are found to be statistically similar to the entire HIPASS BGC. In addition to these galaxies, the HIPASS BGC contains four previously unknown HI clouds.Comment: 39 pages including 14 figures, to appear in the Oct 2002 issue of A
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