Global Telescope has 10x's the Resolution of the Hubble

Astronomers at the Arecibo Observatory in Puerto Rico joined a project called Electronic Very Long Baseline Interferometry (e-VLBI), which can make temporary radio telescopes that rival the size of the Earth, spanning North America, South America, Europe and Africa.

The e-VLBI's size gives it 10 times the resolution of the Hubble Space Telescope, allowing the array to image objects - like the bright 'afterglow' formed when a high-speed jet of matter from a gamma-ray burst slams into its surroundings, that just look like points to individual radio telescopes, according to Chris Salter of Arecibo. Now, with the e-VLBI, the data is sent via fiber optic cables to produce real-time images of celestial objects. That allows astronomers to easily plan follow-up observations for rapidly changing phenomena, such as supernovae.

Boosting the amount of data that can be sent to build larger, Earth-sized arrays vastly improve their sensitivity, according to Mark Reid of the Harvard-Smithsonian Center for Astrophysics in Cambridge. VLBI observations routinely produce images hundreds of times more detailed than those made at visible-light wavelengths by the Hubble Space Telescope.

An international team of scientists led by Reid has used VLBI to detect the slight change in apparent position of the object at the Milky Way's center caused by our Solar System's orbit around that center. "It takes our Solar System more than 200 million years to circle the center of our Galaxy, and yet we can detect that motion in only a couple weeks with the Very Large Base Array (VLBA) -- truly astounding!" Reid said.

The VLBA studies of the Galactic Center have shown that an object called Sagittarius A* is at the exact gravitational center of our Galaxy. That means, the scientists say, that the object must be incredibly massive. "The VLBA measurements, combined with infrared observations of stellar orbits around this object, provide overwhelming evidence that it's a supermassive black hole," Reid explained. "These observations are also going to make it possible to re-define the coordinate system used to map the entire Galaxy," Reid added.

Looking farther outward, astronomers achieved a longstanding goal of measuring the spin of another galaxy. In 2005, Reid and his colleagues measured both the rotational spin and the motion in space of the galaxy M33, nearly 2.4 million light-years from Earth. Astronomers in the 1920s had attempted such a feat, but their results were not accurate enough. "This achievement had to wait for the VLBA," Reid said. This and subsequent work has put strong limits on the amount of unseen "dark matter" around the giant Andromeda galaxy, which M33 orbits.

A continuing goal is to use VLBI observations to measure the orbits of these and other galaxies within the Local Group of galaxies to which our own Milky Way belongs.

Posted by Casey Kazan.