Publication
The view from the ice at the bottom of the world: Optical astronomy from Antarctica

Dempsey, Jessica Tui, 2005, Ph.D. Thesis | View on ADS (2005PhDT........20D)

Abstract

The high Antarctic plateau may offer the best site on earth for optical astronomy. This thesis work includes the construction of an infrared cloud- observing instrument, COBBER, which utilises a thermopile detector optimised at 10 mm. COMER was installed at Dome C in January 2003. In 71 observing days, only four days of cloud were measured. A detailed study of the effect of auroral emission on optical observations is conducted. Analysis of auroral measurements at South Pole show that in an average winter season, the B band sky brightness is below 21.9 mag/arcsec 2 for 50% of the observing time. In V band, the median sky brightness contribution is 20.8 mag/arcsec 2 in an average winter. Calculations are used to show that at Dome C, the contribution to sky background in B and V is up to 3.1 magnitudes less than at South Pole. The first optical stellar spectra observed from the high Antarctic plateau were taken at South Pole station with the Antarctic Fibre Optic Spectrometer (AFOS). The AFOS was installed on a dual-telescope alt-az mount in January of 2003. A thorough instrument analysis revealed tower sinkage and telescope flexure problems that were overcome with more frequent pointing runs. Two years of AFOS observations are described, including selection of sources, design of observing scripts and the creation of a data reduction method for the data. AFOS data was analysed to determine if the H 2 O atmospheric absorption bands in the spectra could be used to detect daily variations in the precipitable water vapour (PWV) content of the atmosphere. The PWV values obtained by comparing the AFOS data with synthetic spectra created with MODTRAN were compared to similar measurements taken at South Pole with a 350 mm radiometer and balloon-borne radiosondes. The PWV values from these instruments showed good agreement with the AFOS results. Observations of the moon were used to study the earthshine spectrum to detect variations in the earth albedo over a 24-hour period. The earth albedo was successfully detected though poor weather conditions prevented study of any long-term trends in the data.