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The MeerKAT Fornax Survey maps the distribution and kinematics of atomic neutral hydrogen gas (HI) in the nearby Fornax galaxy cluster using the MeerKAT telescope. The 12 deg^2 survey footprint covers the central region of the cluster out to ~ Rvir and stretches out to ~ 2 Rvir towards south west to include the NGC 1316 galaxy group. The HI column density sensitivity (3 sigma over 25 km/s) ranges from 5e+19/cm^2 at a resolution of ~ 10" (~ 1 kpc at the 20 Mpc distance of Fornax) down to ~ 1e+18/cm^2 at ~ 1' (~ 6 kpc), and slightly below this level at the lowest resolution of ~ 100" (~ 10 kpc). The HI mass sensitivity (3 sigma over 50 km/s) is 6e+5 Msun. The HI velocity resolution is 1.4 km/s. In this paper we describe the survey design and HI data processing, and we present a sample of six galaxies with long, one-sided, star-less HI tails (of which only one was previously known) radially oriented within the cluster and with measurable internal velocity gradients. We argue that the joint properties of the HI tails represent the first unambiguous evidence of ram pressure shaping the distribution of HI in the Fornax cluster. The disturbed optical morphology of all host galaxies supports the idea that the tails consist of HI initially pulled out of the galaxies' stellar body by tidal forces. Ram pressure was then able to further displace the weakly bound HI and give the tails their present direction, length and velocity gradient., Comment: Astronomy & Astrophysics, accepted. Data available at the MeerKAT Fornax Survey website https://sites.google.com/inaf.it/meerkatfornaxsurvey

To investigate galaxy properties as a function of their total stellar mass, we obtained 21cm HI line observations at the 100-m class Nan��ay Radio Telescope of 2839 galaxies from the Sloan Digital Sky Survey (SDSS) in the Local Volume (900, 71 pages, 14 figures

Upcoming HI surveys will deliver large datasets, and automated processing using the full 3-D information (two positional dimensions and one spectral dimension) to find and characterize HI objects is imperative. In this context, visualization is an essential tool for enabling qualitative and quantitative human control on an automated source finding and analysis pipeline. We discuss how Visual Analytics, the combination of automated data processing and human reasoning, creativity and intuition, supported by interactive visualization, enables flexible and fast interaction with the 3-D data, helping the astronomer to deal with the analysis of complex sources. 3-D visualization, coupled to modeling, provides additional capabilities helping the discovery and analysis of subtle structures in the 3-D domain. The requirements for a fully interactive visualization tool are: coupled 1-D/2-D/3-D visualization, quantitative and comparative capabilities, combined with supervised semi-automated analysis. Moreover, the source code must have the following characteristics for enabling collaborative work: open, modular, well documented, and well maintained. We review four state of-the-art, 3-D visualization packages assessing their capabilities and feasibility for use in the case of 3-D astronomical data., 19 pages, 6 figures, 2 tabular. Accepted for publication in Astronomy and Computing

We used the Nan\c{c}ay Radio Telescope (NRT) to measure the 21 cm line emission of near-infrared bright galaxies in the northern Zone of Avoidance (ZoA) without previous redshift determinations. We selected galaxies with extinction-corrected magnitudes $K_s^o \leq 11\hbox{$.\!\!^{\rm m}$}25$ from the 2MASS Extended Source Catalog. These data will complement the existing 2MASS Redshift Survey (2MRS; first data release) as well as the ongoing 2MASS Tully-Fisher survey, both of which exclude the inner ZoA ($|b|< 5^{\circ}$), where the identification of galaxy candidates is the hardest. Of the $\sim$1000 identified 2MASX galaxy candidates we have so far detected 252 to our 3.0 mJy rms sensitivity limit and the velocity limit of 10500 km/s. The resulting redshift distribution reveals various new structures that were hitherto uncharted. They seem to form part of the larger Perseus-Pisces Supercluster (PPS). The most conspicuous is a ridge at about $\ell\approx 160^{\circ}$,$v \approx 6500$ km/s. Within this wall-like structure, two strong radio galaxies (3C 129 and 3C 129.1) are embedded which lie at the same distance as the ridge. They seem to form part of an X-ray cluster. Another prominent filament has been identified crossing the ZoA at $\ell \approx 90^\circ$, hence suggesting the second Perseus-Pisces arm is more extended than previously thought., Comment: 6 pages, 1 figure, in Proceedings of SAIP2012: the 57th Annual Conference of the South African Institute of Physics, edited by Johan Janse van Rensburg (2014), pp. 368 - 372. ISBN: 978-1-77592-070-0