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WHAT HAS CARA DISCOVERED SO FAR FROM THE SOUTH POLE?

11/22/94 J. S. Sweitzer

The Center for Astrophysical Research in Antarctica (CARA) operates three different fundamental experiments from the South Pole. All are for determining how objects like stars and galaxies began forming in the universe. A fourth line of investigation is working to understand how good the South Pole is as an astronomical site. This research requires observing at several different wavelengths of light from the near infrared to waves a few millimeters long. Several specially designed telescopes have been created to observe cosmic objects and structure at these wavelengths. CARA is only a few years old, so up until now most of the efforts of its scientists and engineers have gone into establishing the buildings and telescopes necessary to make the observations. Nevertheless, a few of the experiments are now beginning to provide an answers to questions about the early universe and about the quality of the air above the Pole.

The Cosmic Background Radiation Anisotropy Experiment (COBRA) seeks to measure small changes in the radiation from the big bang. This radiation began its journey when the universe was as hot as the surface of our Sun and a thousand times smaller than it is now. COBRA scientists have twice detected slight irregularities in this light of the big bang. These irregularities are about one degree in scale and extremely subtle (34 million times dimmer than the cosmic background radiation itself). Although these first results have been confirmed, they are still limited, because they only map a few positions on the sky. In the coming years, the COBRA team will create a 100 square degree map of the early universe with a resolution scale of one degree. This is very important, because the largest structures (clusters of galaxies) that we know of in the universe arose from irregularities of just this scale.

The South Pole Infrared Explorer (SPIREX) has just finished its first winter season at the Pole. Its first objective is to measure how much infrared light is emitted by the sky. The results of the current experiments have not been totally analyzed, but the first look at the data indicates that indeed the sky over the Pole emits very little infrared light -- many times less than the sky over the observatory on Mauna Kea in Hawaii. This is good because it means that the site is the best know on the Earth. SPIREX investigators got and extra bonus this past season. During the time of the collision of comet Shoemaker/Levy with Jupiter in July, the SPIREX telescope observed ten of the impacts*. No other telescope on Earth could perform such a feat. This is because during July, Jupiter was above the horizon continuously at the South Pole and never set.

ATP is the acronym given by CARA to the Advanced Telescopes Project. Its primary goal is to evaluate the South Pole and other Antarctic locations for how steady the air is (seeing) and for sky transparency. The only results that have been published are for the transparency and steadiness of the air due to water vapor. The ATP researchers have shown that the polar air is extremely dry and stays so for very long periods of time. This is especially important for astronomers working in the sub millimeter region of the spectrum.

AST/RO is the fourth project that CARA operates. AST/RO scientists have constructed and tested their sub millimeter telescope in Boston. At the end of this year the AST/RO telescope will be shipped to the South Pole. Some time around Christmas it will be installed atop its specially designed laboratory building at the South Pole. In the first part of 1995 it will begin mapping clouds where stars are forming in our galaxy.


* A great poster showing all these collisions can be obtained from Yerkes Observatory. Write J. Bausch (jab@hale.yerkes.uchicago.edu) for information on how to order it. The file "spposter" describes the poster.

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