An Optical Ultra-High-Resolution Cross-dispersed Echelle Spectrograph with Adaptive Optics

A prototype cross-dispersed optical echelle spectrograph of very high resolution has been designed and built at Steward Observatory and tested at the Starfire Optical Range (SOR) 1.5 m telescope. It is the first spectrograph to take advantage of diffractionlimited images provided by adaptive optics in order to achieve a potential resolving power of R ∼ 600, 000. The wavelength coverage in a single exposure is about 300 Å, which is approximately 100 times that of conventional spectrographs operating at comparable resolution. This was achieved by recording 60 cross-dispersed orders across the 18×18 mm area of the CCD detector. The total efficiency of the system, including the sky and telescope transmission, spectrograph and CCD detector, is measured to be 1.3% at peak, much higher than that of other ultra-high-resolution spectrographs. Sample stellar spectra with R ∼ 250, 000 are presented. Permanent Address: Department of Astronomy & Astrophysics, Penn State University, University Park, PA 16802 [email protected]