GENS4001-X1Observing the Universe / Antarctic Astronomy 1 Lecture 4: Observing the Universe and Astronomy in Antarctica Dr Michael Burton

GENS4001-X1Observing the Universe / Antarctic Astronomy 2 The Nature of Light Light travels through space at a finite speed –300,000 kilometres per second. Wavelength of visible light is associated with its colour. –So is Temperature (blue=hot, red=cold). Radio waves, infrared, visible light, x-rays are all part of the electromagnetic spectrum. Objects change appearance with wavelength

GENS4001-X1Observing the Universe / Antarctic Astronomy 3 The Spectrum Light can be split into a spectrum by a prism. The spectrum of light from a star consists of –Continuum radiation (colours) due to its temperature, –Dark lines from absorption by (cool) elements, –Bright lines from emission by (hot) elements. Provides a fingerprint to identity.

GENS4001-X1Observing the Universe / Antarctic Astronomy 4 Telescopes Light is bent or ‘refracted’ by a lens. Curved mirrors also focus light. Telescopes collect and focus light and –Brighten, –Resolve, –Magnify astronomical objects. Refracting and Reflecting Telescopes.

GENS4001-X1Observing the Universe / Antarctic Astronomy 5 The Earth’s Problem Atmosphere Only passes visible, radio and some infrared radiation. Causes stars to twinkle. Emits radiation, especially in infrared (heat) Has weather!

GENS4001-X1Observing the Universe / Antarctic Astronomy 6 Recent Innovations Electronic (CCD) detectors instead of photographic plates. Detectors for new wavebands (eg infrared). Adaptive optics to take out atmospheric blurring or “seeing”. New engineering technology allows giant mirrors (8-10m) to be built. Satellites.

GENS4001-X1Observing the Universe / Antarctic Astronomy 7 Limits to Progress in Astronomy Technology Poor atmospheric transmission Local sources of interference Thermal background Choice of observing site –Desert mountain tops –Space –Antarctic Plateau

Observatories of the World Royal Observatory Edinburgh (city) Siding Spring Observatory –AAT, Schmidt, 2.3m, UNSW APT Mauna Kea Observatory, Hawaii –UKIRT, Keck, Gemini, JCMT,… La Silla Observatory, Chile Australia Telescope –Parkes, Narrabri, Mopra Space Telescopes

GENS4001-X1Observing the Universe / Antarctic Astronomy 9 Antarctica High ice plateau –2900m at South Pole to 4300m at Dome Argus Extremely cold –Average temperature -50°C to < -90°C Exceedingly dry –By far driest desert on Earth Low wind speeds –Katabatic wind < 5 m/s

GENS4001-X1Observing the Universe / Antarctic Astronomy 10 Potential of Antarctic Astronomy Darkest sky –Less ‘heat’ radiation in infrared. Driest air –Improved transmission from less water. Steadiest air –No diurnal cycle, stable weather. Clearest air Minimal interference

South Pole Astronomy Projects USA, Australia, Germany, Sweden CARA (Photon astronomy) –SPIREX: infrared –AST/RO: sub-millimetre –VIPER: cosmic microwave background AMANDA (particle astronomy) –Neutrinos –Cosmic Rays AASTO – Site Testing

GENS4001-X1Observing the Universe / Antarctic Astronomy 12 UNSW at the South Pole Site testing experiments 1994–1997 –Jamie Lloyd wintered 95/96. SPIREX/Abu 1998–1999. –Infrared camera & telescope. AASTO: since 1998 –Automated, mobile site testing observatory.

GENS4001-X1Observing the Universe / Antarctic Astronomy 13 The Future? AASTO to Dome C in 2002 Douglas Mawson Telescope – 2m Telescope at Dome C in 2004?? And eventually……. The Ultimate Earth-Based Observatory at Dome Argus