This technique ( referred to as e-VLBI ) was pioneered by the EVN ( European VLBI Network ) who now perform an increasing number of scientific e-VLBI projects per year.

The greater telescope separations are possible in VLBI due to the development of the closure phase imaging technique by Roger Jennison in the 1950s, allowing VLBI to produce images with superior resolution.

However, since the VLBI technique measures the time differences between the arrival of radio waves at separate antennas, it can also be used " in reverse " to perform earth rotation studies, map movements of tectonic plates very precisely ( within millimetres ), and perform other types of geodesy.

Recently it has become possible to connect the VLBI radio telescopes in real-time, while still employing the local time references of the VLBI technique, in a technique known as e-VLBI.

In Europe, six radio telescopes of the European VLBI Network ( EVN ) are now connected with Gigabit per second links via their National Research Networks and the Pan-European research network GEANT2, and the first astronomical experiments using this new technique have been successfully conducted.

Very Long Baseline Interferometry ( VLBI ) achieves ultra-high angular resolution and is a multi-disciplinary technique e. g. imaging of extragalactic radio sources, geodesy and astrometry.

Because they are so distant, they are apparently stationary to our current technology, yet their positions can be measured with the utmost accuracy by Very Long Baseline Interferometry ( VLBI ); positions of most are known to 0. 001 arcsecond or better, orders of magnitude more precise than the best optical measurements.

Doppler radio measurements of Huygens from Earth were made, though not as accurate as the expected measurements that Cassini would have made ; when added to accelerometer sensors on Huygens and VLBI tracking of the position of the Huygens probe from Earth, reasonably accurate wind speed and direction measurements could still be derived.

The VLBI radio observations of Sagittarius A * could also be aligned centrally with the images so S2 could be seen to orbit Sagittarius A *.

The corresponding EVN e-VLBI image ( right ) shows the much finer structure of the masers because of the higher resolution of the VLBI array.

Some of the telescopes are occasionally used for EVN and VLBI observations in order to create an interferometer with even larger baselines, providing images with much greater angular resolution.

In the case of VLBI, they all observe the same source at the same time, allowing much higher spatial resolution.

When one or both of these arrays are combined with one or more space-based VLBI antennas such as HALCA ( previously ) and now with RadioAstron ( Spektr-R ), the resolution obtained is higher than any other astronomical instrument, capable of imaging the sky with a level of detail measured in microarcseconds.

Radio images of some individual sources in the field have been made with the European VLBI Network at 1. 6 GHz with a higher resolution than the Hubble maps.

However, the availability today of worldwide, high-bandwidth optical fibre networks makes it possible to do VLBI in real time.

Project manager Stephen Merkowitz talks about his work with NASA's Space Geodesy Project, including a brief overview of the four fundamental techniques of space geodesy: GPS, VLBI, SLR, and DORIS.

VLBI systems using post-observation processing have been constructed with antennas thousands of miles apart.

The pre-eminent VLBI arrays operating today are the Very Long Baseline Array ( with telescopes located across North America ) and the European VLBI Network ( telescopes in Europe, China, South Africa and Puerto Rico ).

Jodrell Bank has been involved with Very Long Baseline Interferometry ( VLBI ) since the late 1960s ; the Lovell telescope took part in the first transatlantic interferometer experiment in 1968, with other telescopes being those at Algonquin and Penticton in Canada.

The Lovell Telescope and the Mark II telescopes are regularly used for VLBI with telescopes across Europe ( the European VLBI Network ), giving a resolution of around 0. 001 arcseconds.

At ground level, the Earth-based doppler shift and VLBI measurements show gentle winds of a few metres per second, roughly in line with expectations.

A variety of methods to establish this reference frame link before catalogue publication were included and appropriately weighted: interferometric observations of radio stars by VLBI networks, MERLIN and VLA ; observations of quasars relative to Hipparcos stars using CCDs, photographic plates, and the Hubble Space Telescope ; photographic programmes to determine stellar proper motions with respect to extragalactic objects ( Bonn, Kiev, Lick, Potsdam, Yale / San Juan ); and comparison of Earth rotation parameters obtained by VLBI and by ground-based optical observations of Hipparcos stars.

Using VLBI in this manner requires large numbers of time difference measurements from distant sources ( such as quasars ) observed with a global network of antennas over a period of time.

This is a part-time array with the data being processed at the Joint Institute for VLBI in Europe ( JIVE ).

This is used to perform radio astronomy with an extended baseline VLBI, of which one element is a space-based antenna.

More recently experiments have been conducted with " electronic " VLBI ( e-VLBI ) where the data are sent by fibre-optics ( e. g., 10 Gbit / s fiber-optic paths in the European GEANT2 research network ) and not recorded at the telescopes, speeding up and simplifying the observing process significantly.

Very-long-baseline interferometry ( VLBI ) is a type of astronomical interferometry used in radio astronomy.

In VLBI interferometry, the digitized antenna data are usually recorded at each of the telescopes ( in the past this was done on large magnetic tapes, but nowadays it is usually done on large RAID arrays of computer disk drives ).

Very Long Baseline Interferometry ( VLBI ) is a type of astronomical interferometry used in radio astronomy.

It belongs to the broader field of space geodesy, which also includes such techniques as geodetic very long baseline interferometry ( VLBI ) and lunar laser ranging.

It has been operating since 1993 and is used primarily for geodetic very long baseline interferometry ( VLBI ).

The 26 metre telescope is used in Australia's very long baseline interferometry ( VLBI ) network.

While negligible for most human activities, terrestrial tides ' semi-diurnal amplitude can reach about at the equator — due to the sun — which is important in GPS calibration and VLBI measurements.

Nowadays, UT in relation to International Atomic Time ( TAI ) is determined by Very Long Baseline Interferometry ( VLBI ) observations of distant quasars, a method which has an accuracy of microseconds.

In September 2002 he led a team which conducted a high-precision VLBI experiment to measure the fundamental speed of gravity.

A 25m-diameter radio telescope is located in Chichijima, which is one of the stations of the VLBI Exploration of Radio Astrometry ( VERA ) project, and is operated by the National Astronomical Observatory of Japan.

SLR stations form an important part of the international network of space geodetic observatories, which include VLBI, GPS, DORIS and PRARE systems.

HALCA ( Highly Advanced Laboratory for Communications and Astronomy ), also known for its project name VSOP ( VLBI Space Observatory Programme ), or the code name MUSES-B ( for the second of the Mu Space Engineering Spacecraft series ), is a Japanese 8 meter diameter radio telescope satellite which was used for Very Long Baseline Interferometry ( VLBI ).

300pxAn optical image of the galaxy Messier 87 | M87 ( Hubble Space Telescope | HST ), a radio image of same galaxy using Interferometry ( Very Large Array-VLA ), and an image of the center section ( VLBA ) using a Very Long Baseline Array ( Global VLBI ) consisting of antennas in the US, Germany, Italy, Finland, Sweden and Spain.

Being a part of the Australia Telescope, it is often used in conjunction with other AT antennas ( e. g., the Australia Telescope Compact Array at Narrabri, and the 64-metre Parkes dish ) to form a Very Long Baseline Interferometry ( VLBI ) array.

The image to the right shows the first science produced by the European VLBI Network using e-VLBI.

The JPL SVLBI project, funded by NASA, supports the VSOP ( VLBI Space Observatory Program ) mission developed by the Institute of Space and Astronautical Science ( ISAS ) in Japan.

Finally, a team led by Marc V. Gorenstein observed essentially identical relativistic jets on very small scales from both A and B in 1983 using VLBI ( Very Long Baseline Interferometry ).

The Joint Institute for VLBI in Europe ( JIVE ) was formed in 1993 by the European Consortium for VLBI and is a member of the European VLBI Network ( EVN ).

by means of experimental VLBI observations with HALCA and terrestrial radio telescope networks

The European VLBI Network ( EVN ) was formed in 1980 by a consortium of five of the major radio astronomy institutes in Europe ( the European Consortium for VLBI ).