Systematic surveys of astronomical objects often lead to discoveries, but always provide invaluable information for statistical studies of well-defined samples. They also promote follow-up investigations of individual objects or classes. Surveys using a yet unexplored observing wavelength, a novel technique or a new instrument are of special importance. Significantly improved observing paramete...

The high resolution obtained through the use of VLBI gives an unique opportunity to directly observe the interaction of an expanding radio supernova with its surrounding medium. We present here results from our VLBI observations of the young supernovae SN 1979C, SN 1986J, and SN 2001gd.

Sagittarius A*, the ∼ 4 × 106 M⊙ black hole candidate at the Galactic Center, can be studied on Schwarzschild radius scales with (sub)millimeter wavelength Very Long Baseline Interferometry (VLBI). We report on 1.3 mm wavelength observations of Sgr A* using a VLBI array consisting of the JCMT on Mauna Kea, the ARO/SMT on Mt. Graham in Arizona, and two telescopes of the CARMA array at Cedar Flat...

In order to enable VLBI observations of satellite targets on a regular basis, proper scheduling procedures need to be in place. The Vienna VLBI Software VieVS has been used to schedule about 40 of these test sessions, triggering large developments in the scheduling tools. We report on the current capabilities of the available software and discuss present difficulties when preparing a new experi...

I present an overview of important results obtained using high-resolution very long baseline interferometry (VLBI) observations of X-ray binary systems. These results derive from both astrometric observations and resolved imaging of sources, from black holes to neutron star and even white dwarf systems. I outline a number of upcoming developments in instrumentation, both new facilities and ongo...

I present an introductory review text, focusing on recent deep field studies using radio telescopes, including high-resolution, widefield VLBI observations. The nature of the faint radio source population is discussed, taking into account complimentary data and results that are now available via the sub-mm, IR, optical and X-ray wavebands. New developments regarding the increased sensitivity of...

VLBI at millimeter wavelengths (mm-VLBI) allows the detailed imaging of compact galactic and extragalactic radio sources with micro-arcsecond scale resolution, unaccessible by other observing techniques. Here we discuss the scientific potential of mm-VLBI for present and future research on 'Active Galactic Nuclei' (AGN) and their powerful relativistic jets. With the new generation of large radi...

This memo reviews the requirements for using the ALMA array as a part of a global VLBI array at millimeter wavelengths. ALMA can be outfitted for VLBI at modest cost and should be planned with this capability in mind, as it may be more difficult to retrofit at a later date. The essential features required in the ALMA design are discussed.

Recently, there has been an international effort to create an Event Horizon Telescope (EHT) capable of imaging a black hole’s event horizon for the first time. Imaging distant celestial sources, such as the event horizon of a black hole, with high resolving power (i.e. small angular resolution) requires telescopes with prohibitively large diameters due to the inverse relationship between angula...

Manuscript received May 28, 1999. † The authors are with Communications Research Laboratory, Koganei-shi, 184-8795 Japan. †† The authors are with NTT Multimedia Networks Laboratories, Musashino-shi, 180-8585 Japan. ††† The author is with NTT Advanced Technology Corporation, Yokohama-shi, 244-0801 Japan. †††† The authors are with National Astronomical Observatory, Mitaka-shi, 181-8588 Japan. ‡‡†...