Measurement of atmospheric opacity at 278 GHz at McMurdo Station, Antarctica in austral spring seasons, 1986 and 1987

We present a quasi-continuous record of measured atmospheric opacity obtained at 278 GHz (1.1 mm wavelength) from McMurdo Station, Antarctica during austral spring seasons in 1986 and 1987. McMurdo Station, at 78°S, 166°W, is easier to access than the Amundsen-Scott (South Pole) Station, although representing a warmer, sea level site with substantially higher typical opacity: the present record may be of interest to those contemplating mm-wave astronomical or atmospheric observations within the Antarctic region. Observations were made over a 256 MHz bandpass in 1986, during the period August 30 to October 30. In 1987, a 512 MHz bandpass was used, and observations were made during the period September 4 to October 13. All data are reduced to represent opacity in the zenith direction, and measurements were taken approximately every 20 minutes, except during storms or other periods of high opacity. The periods covered represent transitions from the polar winter towards summer conditions, and thus represent neither the best nor the worst that this site has to offer.