Shami Chatterjee: Telescopes

Telescopes We Work With

(Click on images for larger versions)

Optical telescopes need dark skies, and radio telescopes require a site free from radio interference. Telescopes need to be located in remote and exotic locations, far from city lights and smog and cell phones: on islands like Puerto Rico, in the deserts of New Mexico, on mountain tops in California...

So one of the pleasures of being an astronomer is travelling to various telescopes on observing trips. The locations are great, the people running the observatories are simply fantastic, and the trips are always fun.

That's how it used to be, anyway. Nowadays, civilization is harder to get away from: a tiny cellphone placed on the moon would be the third-brightest source in the entire radio sky! Observatories are also more automated, and some are in space. So data is just as likely to arrive as a tape in the mail - more efficient, no doubt, but not quite the same thing as being there when you're observing.

Here are some telescopes our group has worked with, and my photographs, if I've been on trips out to the site:

The Very Large Array, in New Mexico.
The Very Long Baseline Array, distributed over the US.
Palomar Observatory, home to the 200-inch Hale Telescope, in California.
Arecibo Observatory, the world's largest single-dish radio telescope, in Puerto Rico.
The Giant Meter-wave Radio Telescope, in India.

Our group also uses the Hubble Space Telescope, which orbits the Earth once every 96 minutes: funnily enough, no one has actually gone out to the "site" to observe with this... :-)
The Chandra X-ray Observatory is also in space.

The Very Large Array

Among all the telescopes I've visited, the VLA is my personal favorite, probably because I lived in New Mexico for a year, and saw the array through summer thunderstorms, sparkling winter days and spectacular sunsets. Driving out along US 60 from Socorro, out in the middle of nowhere, the telescopes suddenly come into view like a shimmering mirage: it is a surreal sight.

The VLA is an array of telescopes that can be linked together to synthesize the resolving power of a telescope upto 36 km (22 miles) across, or grouped together to synthesize one only a km (0.6 mile) across: the varying resolutions are the equivalent of an astronomical zoom lens.

Learn more about the VLA.

The Very Long Baseline Array

Imagine a telescope sprawling across all of North America: it's possible, using a dedicated supercomputer to link together an array of ten identical radio telescopes, scattered over the U.S. from the Virgin Islands in the Carribean to Mauna Kea in Hawii. And the result is the highest angular resolution telescope ever built.

Here are photos of one of the 10 dishes (the one at Pie Town, New Mexico), both from the outside and the inside. (Yes, the photo above is of me and an engineer inside the telescope dish on the right.) And here is a link to some more information about the VLBA.

Palomar Observatory

Mount Palomar in California is home to the massive 5-m (200 inch) Hale Telescope: a 530 ton telescope housed in a 1000 ton moving dome. This is the largest single-mirror telescope in the continental US, and the largest in the world when it began operation in 1948. (Larger telescopes have been built since then, in Hawaii and Chile.)

Learn more about Palomar.

Left: The view from across the valley, with a couple of the domes just visible through the early evening haze.

Right: The Hale Telescope, with surreal lighting inside the dome.

Below: The dome at sunset, with the moon above, and after opening the shutters, while observing at night.

Arecibo Observatory

The world's largest single dish telescope, Arecibo Observatory (in Puerto Rico) is simply unique. The fixed reflector on the ground is 305 meters (1000 ft) across, and almost exactly a kilometer (0.6 mile) around. The platform, suspended in mid-air (450 feet above the ground), weighs 900 tons and is about the size of a five-story building!

More about the telescope, and a Tour map.

Right: A view from under the reflector, which is made of perforated aluminium sheets, shows the platform as well as one of the three support towers.

Left: The platform and the Gregorian dome, with the catwalk leading to it, and the telescope surface far below.

Below: Can radio telescopes be abstract art? Views of the wind spoilers on the anchor cables for the platform, two receivers, and the tertiary reflector inside the Gregorian dome.

Through the shimmering wire dish of the GMRT

The Giant Meter-wave Radio Telescope, in India.

To a radio wave with a wavelength of a meter, a wire mesh is as reflective as the finest mirror. The GMRT is a unique instrument that takes advantage of this idea, with 38 shimmering transparent wireframe dishes scattered around Khodad village in Pune, India.

Learn more about the GMRT here: includes more pretty pictures, too.

The Hubble Space Telescope

The HST homepage and the Hubble Heritage Project.

The Chandra X-ray Observatory

Public Information and the Chandra Photo Album.

About these images:

These photographs were taken at various times since 1999, using a Canon EOS Elan II body with a 24-80 mm f/3.5-5.6 lens, on Kodak ISO 400 and ISO 100 film. Scanned in (thanks, Meghan!), cropped and brightness tweaked in Photoshop. For more photo galleries, visit my homepage.

Shami Chatterjee
shami at astro.cornell.edu
Last modified: 23 Sep 2003.