Sutherland in the Northern Cape. The country did even better than these figures suggest, as two-
thirds of the capital cost of the telescope was expended with South African companies.
To protect this advantage, the Department of Science and Technology (DST) sponsored an
Astronomy Geographic Advantage Program (AGAP) bill, recently passed by Parliament. It seeks
to limit the human activities that can be undertaken (from the light and radio interference arising
out of housing developments and mining, for instance) in areas close to South Africa's best
astronomical sites. The extraordinary quality of our African skies is demonstrated by the familiar
night-time compilation image of the Earth, showing southern Africa. The darkness of the Karoo
on a clear, moonless night is truly awe-inspiring.
Modern astronomy, SALT, and the Internet:
Not so long ago (only 25 years), ground-based observational astronomy was conducted with
telescopes using photographic plates, and the main means of communication with the outside
world was by telephone, fax, or telex machine. Conditions have changed dramatically. Telescopes
evolved during the 1980s to being fully computer controlled; and highly efficient, digital
detectors (charge-coupled devices, or CCDs, similar to those now common in digital cameras)
have replaced the photographic plates. But the real transformation came in the 1990s with the
World Wide Web. It revolutionized research communication for all branches of science, and for
astronomy it opened up a host of possibilities. These included the ability to access astronomical
databases compiled and maintained anywhere in the world, as well as the ability to receive and
respond rapidly to time-critical results54. Increasing Internet bandwidth brought the possibility of
shipping data immediately from the telescope to the home base (often overseas) for reduction and
analysis. For many research projects, this needs to be done during the observing run so that
particular observations can quickly be followed up with observations at other wavebands. This
process is being applied to SALT data, but for different reasons.
SALT55 is completing its commissioning phase and has already produced valuable results. But
how does SALT data get to the scientists who want to work with them? There are five large-
formats (8-million-pixel) CCDs in the cameras used by SALT, and a typical night can produce 1-
10 gigabytes of data. Sending such large quantities of data over our existing international links
with Europe and America, for instance, is impossible, so we use a different approach. We have a
dedicated (1.5-million-bits per second) line between Sutherland and Cape Town, which can
transfer a night's data in a few hours (data are sent throughout the night while observing is taking
place).However, these are all raw, uncalibrated data in the form of large files, which are then
processed automatically (using a `pipeline' processing system) into reduced data occupying far
less computer space. These data can then be accessed over the Internet by the SALT partnership's
scientists, both internationally and within South Africa
Astrophysical virtual Observatory:
The 1990s saw massive growth in the volume of astronomical data generated around the world, as
a result of the new generation of large telescopes combined with larger format detectors and more
powerful computing facilities. This was true for all wavelengths, from radio to infrared to optical
to ultraviolet to X-ray, both in space and on the ground.
54
An example of how rapidly scientists can respond to the observation concerns what is happening in the
world of gamma-ray-burster (GRB) research (see Martin Still's article, "The birth of a black hole", in
Quest, vol.3, no. 1, pp. 12-15).
55
For details about SALT, see Quest, vol. 2, no. 2.
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