4 research outputs found
Swimming with ShARCS: Comparison of On-sky Sensitivity With Model Predictions for ShaneAO on the Lick Observatory 3-meter Telescope
The Lick Observatory's Shane 3-meter telescope has been upgraded with a new
infrared instrument (ShARCS - Shane Adaptive optics infraRed Camera and
Spectrograph) and dual-deformable mirror adaptive optics (AO) system (ShaneAO).
We present first-light measurements of imaging sensitivity in the Ks band. We
compare measured results to predicted signal-to-noise ratio and magnitude
limits from modeling the emissivity and throughput of ShaneAO and ShARCS. The
model was validated by comparing its results to the Keck telescope adaptive
optics system model and then by estimating the sky background and limiting
magnitudes for IRCAL, the previous infra-red detector on the Shane telescope,
and comparing to measured, published results. We predict that the ShaneAO
system will measure lower sky backgrounds and achieve 20\% higher throughput
across the bands despite having more optical surfaces than the current
system. It will enable imaging of fainter objects (by 1-2 magnitudes) and will
be faster to reach a fiducial signal-to-noise ratio by a factor of 10-13. We
highlight the improvements in performance over the previous AO system and its
camera, IRCAL.Comment: 13 pages, 5 figures, SPIE Astronomical Telescopes + Instrumentation,
Montreal 201
ShaneAO: wide science spectrum adaptive optics system for the Lick Observatory
A new high-order adaptive optics system is now being commissioned at the Lick
Observatory Shane 3-meter telescope in California. This system uses a high
return efficiency sodium beacon and a combination of low and high-order
deformable mirrors to achieve diffraction-limited imaging over a wide spectrum
of infrared science wavelengths covering 0.8 to 2.2 microns. We present the
design performance goals and the first on-sky test results. We discuss several
innovations that make this system a pathfinder for next generation AO systems.
These include a unique woofer-tweeter control that provides full dynamic range
correction from tip/tilt to 16 cycles, variable pupil sampling wavefront
sensor, new enhanced silver coatings developed at UC Observatories that improve
science and LGS throughput, and tight mechanical rigidity that enables a
multi-hour diffraction- limited exposure in LGS mode for faint object
spectroscopy science.Comment: 11 pages, 10 figures. Presented at SPIE Astronomical Telescopes +
Instrumentation conference, paper 9148-7
Commissioning ShARCS: the Shane Adaptive optics infraRed Camera-Spectrograph for the Lick Observatory 3-m telescope
We describe the design and first-light early science performance of the Shane
Adaptive optics infraRed Camera-Spectrograph (ShARCS) on Lick Observatory's 3-m
Shane telescope. Designed to work with the new ShaneAO adaptive optics system,
ShARCS is capable of high-efficiency, diffraction-limited imaging and
low-dispersion grism spectroscopy in J, H, and K-bands. ShARCS uses a
HAWAII-2RG infrared detector, giving high quantum efficiency (>80%) and Nyquist
sampling the diffraction limit in all three wavelength bands. The ShARCS
instrument is also equipped for linear polarimetry and is sensitive down to 650
nm to support future visible-light adaptive optics capability. We report on the
early science data taken during commissioning.Comment: 9 pages, 7 figures. Presented at SPIE Astronomical Telescopes +
Instrumentation conference, paper 9148-11