Results for ShaneAO - Imaging

With the new system, we retain the IRCAL filter curves, dust fraction of 3% and coating degradation described above. Strehl ratios are derived from [6]. The predicted sky background and throughput for ShaneAO are given in Table 5.

Table 5: Sky background and throughput results for new ShaneAO system.
Filter Average sky Predicted measured Predicted measured Throughput
  brightness brightness (dust=0.0) brightness (dust=0.03) (dust=0.03)
  mag arcsec$ ^{-2}$ mag arcsec$ ^{-2}$ mag arcsec$ ^{-2}$  
J 15.84 15.80 15.80 0.136
H 13.85 13.84 13.82 0.175
K 13.87 11.84 10.40 0.165
Ks 14.60 12.68 11.21 0.171

Comparing Tables 5 and 3, the model predicts that the background in the $ K$ band will be a magnitude fainter and throughput will increase by 20-30% across all bands. The reduced background for ShaneAO is illustrated by Figure 3.

Figure 3: Total background and emissivity comparison as determined by our model between the existing system (IRCAL) and the new system (ShARCS).
Image bg+em-sharcsVirc

For limiting magnitudes, the comparison between current and new systems is one of what is and will be their usual modes of operation:

LGS mode with 8$ \times $8 subapertures and 300 second Fowler-16 exposures.
ShARCS+old laser:
LGS mode with 8$ \times $8 subapertures (ShARCS 8 in the figures and tables below) and 300 second Fowler-16 exposures - this will be the modus operandi for a few months after ShARCS is installed (April 2014 onwards) until the new laser is operational.
Full ShaneAO:
LGS mode with 16$ \times $16 subapertures (ShARCS 16 hereafter) and 300 second Fowler-32 exposures.

Srikar Srinath 2013-10-09