Gigapixel camera searches the skies

12 Oct 2007

The world's largest digital camera will soon be scanning the sky for asteroids that are on a potential crash course with Earth.

1.4 gigapixel CCD camera

A colossal 1.4 gigapixel digital camera has just been deployed on the Pan-STARRS-1 (PS1) telescope in Maui, Hawaii. The PS1 is the first of four identical telescopes that make up a $100 M project designed to search the sky for potentially hazardous asteroids.

"The big revolution of PS1 is to tile focal planes with billions of pixels," Nick Kaiser, a researcher from the University of Hawaii's Institute for Astronomy, told optics.org "What's more, using an 8x8 array of independently addressable little cells allows the system to be read out at an incredible speed."

The camera uses a 64x64 CCD array covering a total area of 40 cm² and produces an image that is 38,000 by 38,000 pixels. Each CCD array contains approximately 600x600 pixels.

Camera assembly

The CCD focal plane will employ orthogonal transfer array CCDs (OTCCDs) made up of 8x8 arrays on a single 5 cm² silicon chip. The OTCCDs, developed at the Massachusetts Institute of Technology's Lincoln Laboratory, are able to read out large amounts of data quickly.

Splitting the image area has additional benefits. Not only does it reduce the "dazzling" effect a very bright star can have on the image but any defects in the sensor chips only affect a small part of the image area.

Each camera will include an identical set of 5 or 6 optical filters that can be remotely positioned in front of the focal plane to image most of the visible spectrum from 0.4 to 0.8 µm.

"PS1 has a higher basic figure of merit (collecting area multiplied by the field of view) than any other existing telescopes. It also has other properties such as rapid read-out and telescope slew time that make it uniquely powerful for wide-field survey work," said Nick. "The main goal is to detect 90 % or more of all potentially hazardous asteroids bigger than 300 m in diameter; determine their orbits and find out if an are going to collide with us in the foreseeable future."

Since so much data will be produced by the camera, the team has developed special software and an ultrafast 480-channel control system to analyze the 1000 images that can be captured per night by each telescope.