The background and limiting magnitudes for the existing camera and AO system were measured and reported in  and are reproduced in Table 2. The model had to be adjusted to include off-axis emission because the IRCAL cold stop is 18% oversized. Strehl ratio for the band was derived from  and scaled for other bands using the relation:
where is the reference Strehl (0.42 in LGS mode and 0.65 in NGS mode in the -band) and the central wavelength of the reference filter. Filter curves were derived from those displayed in the IRCAL manual on the Lick Observatory website.3
Gemini in Table 2 is an older infrared camera and the measurements for it are taken from . The sky backgrounds predicted by the ShaneAO model with no dust coating the optics and a 3% dust coating for the existing system (IRCAL) are in Table 3. The predicted values are in good agreement with the measured values.
Compared to Keck, the dust fraction had to be increased to 3% to better match the IRCAL system's magnitudes and throughput. Since Mauna Kea (the site for the Keck telescopes) is at times the altitude of Mt. Hamilton, increasing the dust fraction for IRCAL by a similar factor seems reasonable. Coating degradation (2.5% for Aluminum and 1% for other surfaces) is the same for both comparisons.
Given the variation in NIR sky emission, the numbers in Tables 2 and 3 are in very good agreement. Further validation is provided by comparing limiting magnitudes for point sources using a natural guide star (NGS) as measured and reported in  and available online4 versus those predicted by our model in Table 4. The unusually low measured throughput in the band is not reproduced by the model but the decrease in throughput between and bands is.
Srikar Srinath 2013-10-09