2019MNRAS.484.3620C

For the first time, multiband atmospheric extinction in Antarctica is reported. Extinction coefficients are derived from 17 500 CCD stellar frames, by use of simultaneous multicolour Johnson-Cousin filters, over a whole polar wintertime. Polar observations were performed using PAIX - Photometer AntarctIca eXtinction, the first Antarctica robotic multiband photometer. Bouguer's lines and then the atmospheric extinction coefficients are inferred from 1.2 and 1.8 airmass continuous and uninterrupted observations of the same target. Besides the known good seeing, large isoplanatic angle, high coherence time, and exceptional light transmission in the whole IR-mm bandwidth, we detect that the blue atmospheric extinction at Dome C is 1.6-1.9 times better than that of the highest ranking ground-based observatories around the world. Moreover, our results show a similar atmospheric extinction value in the V band at Dome C and the ground-based observatories. However, in the R band, the atmospheric extinction coefficient is worse at Dome C than the ranking ground-based observatories. The original polar technology - PAIX - opens a new window towards novel insights in long-term time series stellar pulsation and evolution studies.