Laser Guide Star & Natural Guide Star Adaptive Optics
Keck AO allows observers to obtain near-diffraction limited images at K-band wavelengths and longward. With NGS-AO and R-band seeing better than 1 arcsecond, users can expect on-axis Strehl ratios of 50% or better on guide stars with R-band brighter than 12th magnitude. NGS-AO guide stars must be less than 30 arcseconds from the field of interest. NGS-AO outperforms LGS-AO down to guide stars with R = 14th magnitude. LGS-AO guide stars can be as dim as R = 18th magnitude and be 60 arcseconds from the field of interest.