The Carnegie Planet Finder Spectrograph

摘要

The Carnegie Planet Finder Spectrograph is being constructed for use at the Magellan Telescopes at Las Campanas Observatory in Chile. Its primary scientific objective is the detection of extrasolar planets through monitoring of stellar radial velocity variations. The spectrograph is being optimized for high precision measurement of these velocities with a resolution goal of 1 m s-1. The optical design includes all spherical, standard optical glass and calcium fluoride lenses that function as both camera and collimator in a double-pass configuration. A prism cross-disperser is also used in double-pass and provides a minimum order separation of 4.0 arcsec. An R4 echelle grating is illuminated near true Littrow and provides complete wavelength coverage between 390 nm and 620 nm. Spectral resolution is 38,000 when using a 1 arcsec slit, although slit widths as small as 0.2 arcsec are available. An iodine cell is used to superimpose well-defined absorption features onto spectra to serve as a fiducial wavelength scale, and a thorium argon lamp is available for traditional wavelength calibrations. The spectrograph is currently under construction and is scheduled for commissioning in the second quarter of 2007.