CARA Science:
The Bottom Line: Site Characterization Statistics


Sky emission abouve the South Pole in µJy arcsec^-2, from 1.5-2.5 µm (upper) and 2.9-4.1 µm (lower), obtained with 1% spectral resolution through the IRPS CVF. These are the median of all the "darkest sky" spectra obtained during the winter of 1995. Calibration was performed using a black body source at 0 degrees Centigrade, and fluxes short of 2.1 µm use a nominal clibration factor for the instrument. Note that the upper plot uses a linar, and the lower plot a log, intensity scale. For more information, see Phillips et al. 1999.


Saturation PWV at Pole, 1961-1998. Quartiles of saturation-point PWV distribution during the winter (day-of-year 100-300) for 1961-1998, calculated from balloon-borne pressure and temperature measurements. This figure illustrates the long-term stability of the South Pole climate. Note that these saturated values are the maximum possible PWV. "Good" observing days more than 75% of the time. For more information, see the site testing section of the Stark et al. decadal report.


The cumulative distribution function of brightness fluctuation power for the Python data. Two distributions are shown, one for unbinned data files taken over a few minutes (solid line), and one for the data binned in 6 hour intervals (dash-dot line). The unbinned data files are adequate to determine the 50% and 75% quartiles, but the 6 hour binned cumulative distribution function is needed to achieve adequate signal-to-noise to estimate the 25% quartile. The increased fraction of high fluctuation power data in the 6 hour binned cumulative distribution function results from binning brief periods of high fluctuation power together with periods of low fluctuation power. The quartiles are 0.20, 0.51 and 1.62 mK^2 (before compensating for instrumental effects). For more information, see Lay and Halverson 1999.