Andor Aids Chinese Astronomers

Four highly sensitive frame-transfer CCD cameras from Andor are helping Chinese astronomers scan the night sky above the South Pole for faint, transient sources of light, such as supernovae, gamma-ray bursts and minor planets.

Each of the DV435 1K × 1K cameras records the light captured by four separate 14.5-cm Schmidt-Cassegrain optical telescopes that form the Chinese Small Telescope Array (CSTAR). This has been deployed on Dome A – the highest point on the Antarctic plateau. CSTAR operates totally robotically, and is part of the PLATeau Observatory (PLATO), an automated, self-powered astrophysical site-testing observatory developed by the University of New South Wales in Australia. Dome A is an ideal site for high-resolution imaging since its extremely cold temperatures mean very low levels of both background infrared and water vapor content.

As three of the telescopes have specially chosen filters, and one is filterless, CSTAR can produce a very data-rich photometric catalog as it records the night sky. During field trials, more than 10,000 sources of light as dim as approximately 16th magnitude were successfully detected during each 30-s exposure. This makes CSTAR ideal for studying any variability in these sources, and for discovering new transient sources of light that fall within its field of view.

Frame-transfer technology is perfect for this application because it does not require a mechanical shutter – a prerequisite for troublefree operation when temperatures can fall to –80 °C.

In Andor DV435 frame-transfer CCDs, half the chip is covered by an opaque mask for image storage, and the other half exposed to the signal. This allows for rapid acquisition of sequences of image data at the peak quantum efficiency of about 95 percent. As soon as one frame is exposed, its charge is shifted to the masked area. While the masked frame is being read out, data are still being acquired for the next read out. With no shutter, there are no mechanical delays. In the CSTAR set up, each pixel on the Andor cameras equates to about seconds of arc, allowing fine and systematic scans of the night sky.

For more information, visit: www.andor.com