Belfast, Northern Ireland--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.
Robotic observatory
Each of the 1k x 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," which is the highest point on the Antarctic plateau. CSTAR operates totally robotically, and is part of the PLATeau Observatory (PLATO)--an automated, self-powered astronomy observatory developed by the University of New South Wales (Australia). Dome A is an ideal site for high-resolution imaging since its extremely cold temperatures mean very low levels of both background IR and water vapor content.
As three of the telescopes have specially chosen filters, while one is filter-less, 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, down to about 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.
No mechanical shutter needed
Frame-transfer technology is perfect for this application because it does not require a mechanical shutter--a prerequisite for trouble-free operation when temperatures can fall to -80 degrees C.
In the Andor frame-transfer CCDs, half the chip is covered by an opaque mask for image storage and the other half is exposed to the signal. This allows for rapid acquisition of sequences of image data at the peak quantum efficiency of about 95%. 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 readout. With no shutter, there are no mechanical delays.
For more info, visit www.andor.com.
