Spectrograph

Abstract: We describe the high resolution echelle spectrometer (HIRES) now in operation on the Keck Telescope. HIRES, which is permanently located at a Nasmyth focus, is a standard in-plane echelle spectrometer with grating post dispersion. The collimated beam diameter is 12', and the echelle is a 1 x 3 mosaic, 12' by 48' in total size, of 52.6 gr mmMIN1, R-2.8 echelles. The cross disperser is a 2 x 1 mosaic, 24' by 16 ' in size. The camera is of a unique new design: a large (30' aperture) f/1.0, all spherical, all fused silica, catadioptric system with superachromatic performance. It spans the entire chromatic range from 0.3 (mu) to beyond 1.1 (mu) , delivering 12.6-micron (rms) images, averaged over all colors and field angles, without refocus. The detector is a thinned, backside-illuminated, Tektronix 2048 x 2048 CCD with 24-micron pixels, which spans the spectral region from 0.3 (mu) to 1.1 (mu) with very high overall quantum efficiency. The limiting spectral resolution of HIRES is 67,000 with the present CCD pixel size. The overall 'throughput' (resolution x slit width) product achieved by HIRES is 39,000 arcseconds. Peak overall efficiency for the spectrograph (not including telescope and slit losses) is 13% at 6000 angstrom. Some first-light science activities, including quasar absorption line spectra, beryllium abundances in metal-poor stars, lithium abundances in brown-dwarf candidates, and asteroseismology are discussed.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Abstract: The Infrared Spectrograph (IRS) is one of three science instruments on the Spitzer Space Telescope .T he IRS comprises four separate spectrograph modules covering the wavelength range from 5.3 to 38 � m with spectral resolutions, R ¼ k=� k � 90 and 600, and it was optimized to take full advantage of the very low background in the space environment. The IRS is performing at or better than the prelaunch predictions. An autonomous target acquisition capability enables the IRS to locate the mid-infrared centroid of a source, providing the information so that the spacecraft can accurately offset that centroid to a selected slit. This feature is particularly useful when taking spectra of sources with poorly known coordinates. An automated data-reduction pipeline has been developed at the Spitzer Science Center. Subject headingg infrared: general — instrumentation: spectrographs — space vehicles: instruments

Abstract: The James Webb Space Telescope (JWST) is a large (6.6 m), cold (<50 K), infrared (IR)-optimized space observatory that will be launched early in the next decade into orbit around the second Earth–Sun Lagrange point. The observatory will have four instruments: a near-IR camera, a near-IR multiobject spectrograph, and a tunable filter imager will cover the wavelength range, 0.6 < ; < 5.0 μ m, while the mid-IR instrument will do both imaging and spectroscopy from 5.0 < ; < 29 μ m. The JWST science goals are divided into four themes. The key objective of The End of the Dark Ages: First Light and Reionization theme is to identify the first luminous sources to form and to determine the ionization history of the early universe. The key objective of The Assembly of Galaxies theme is to determine how galaxies and the dark matter, gas, stars, metals, morphological structures, and active nuclei within them evolved from the epoch of reionization to the present day. The key objective of The Birth of Stars and Protoplanetary Systems theme is to unravel the birth and early evolution of stars, from infall on to dust-enshrouded protostars to the genesis of planetary systems. The key objective of the Planetary Systems and the Origins of Life theme is to determine the physical and chemical properties of planetary systems including our own, and investigate the potential for the origins of life in those systems. Within these themes and objectives, we have derived representative astronomical observations. To enable these observations, JWST consists of a telescope, an instrument package, a spacecraft, and a sunshield. The telescope consists of 18 beryllium segments, some of which are deployed. The segments will be brought into optical alignment on-orbit through a process of periodic wavefront sensing and control. The instrument package contains the four science instruments and a fine guidance sensor. The spacecraft provides pointing, orbit maintenance, and communications. The sunshield provides passive thermal control. The JWST operations plan is based on that used for previous space observatories, and the majority of JWST observing time will be allocated to the international astronomical community through annual peer-reviewed proposal opportunities.

Abstract: We describe an IDL‐based package for the reduction of spectral data obtained with SpeX, a medium‐resolution, 0.8–5.5 μm cross‐dispersed spectrograph and imager for the NASA Infrared Telescope Facility. The package, called Spextool, carries out all the procedures necessary to produce fully reduced spectra including preparation of calibration frames, processing and extraction of spectra from science frames, wavelength calibration of spectra, and flux calibration of spectra. The package incorporates an “optimal extraction” algorithm for point‐source data and also generates realistic error arrays associated with the extracted spectra. Because it is fairly quick and easy to use, requiring minimal user interaction, Spextool can be run by observers at the telescope to estimate the signal‐to‐noise ratio of their data. We describe the procedures incorporated into Spextool and show examples of extracted spectra.