Showing papers in "Astronomical Telescopes and Instrumentation in 1998"
TL;DR: The NIRSPEC, a near-IR echelle spectrograph for the Keck II 10-meter telescope is described in this paper, which employs diamond-machined metal optics and state-of-the-art IR array detectors for high throughput and powerful user-friendly software for ease of use.
Abstract: The design and development of NIRSPEC, a near-IR echelle spectrograph for the Keck II 10-meter telescope is described. This instrument is a large, facility-class vacuum-cryogenic spectrometer with a resolving power of R equals 25,000 for a 0.4 inch slit. It employs diamond-machined metal optics and state-of-the-art IR array detectors for high throughput, together with powerful user-friendly software for ease of use.
755 citations
TL;DR: The Hobby-Eberly Telescope (HET) as mentioned in this paper is a recently completed 9-meter telescope designed to specialize in spectroscopy, and it has been used extensively in the field of astronomy.
Abstract: The Hobby-Eberly telescope (HET) is a recently completed 9- meter telescope designed to specialize in spectroscopy. It saw first light in December 1996 and during July 1997, it underwent its first end-to-end testing acquiring its first spectra of target objects. We review the basic design of the HET. In addition we summarize the performance of the telescope used with a commissioning spherical aberration correlator and spectrograph, the status of science operations and plans for the implementation of the final spherical aberration corrector and facility class instruments.
288 citations
TL;DR: The Hobby-Eberly Telescope (HRS) as mentioned in this paper is a high-resolution spectrograph with a fiber-instrument feed that is mounted on a Newport bench in an insulated chamber in the 'basement' of the HET building.
Abstract: A high-resolution spectrograph (HRS) is taking shape for the Hobby-Eberly Telescope (HET). HRS will be mounted on a Newport bench in an insulated chamber in the 'basement' of the HET building, internal to the pier, and will be linked to the corrected prime focus of the HET through its Fiber Instrument Feed. Spectra will be recorded on a 4096 X 4096 Orbit CCD mosaic at resolving powers of 30,000 to 120,000, using a mosaic of two R-4 echelle gratings replicated on a single blank at Spectronic Instruments and a selection of two cross- dispersing gratings. This paper will describe the design and report on the current construction status, and will describe innovative aspects, in particular a new all-refractive camera designed by Epps. The HRS design incorporates Barranne's white-pupil concept as adapted for ESO's VLT by Delabre and Dekker. Predicted performance from ray-trace analysis will be demonstrated. With the 316-gr/mm cross-dispenser the full 420 - 1,100 nm spectral range can be recorded in two exposures at any resolving power up to 120,000. Greater order separation can be had with the 600-gr/mm grating, requiring four exposures if the full range is needed. Designed for remote, queue-scheduled operation, HRS will be capable of rapid response to discoveries of transient phenomena. It will be directed toward discoveries of extra-solar planetary systems and studies of long-period variable stars and absorption line systems in QSOs as well as stellar nucleosynthesis and chemical compositions.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
243 citations
TL;DR: The Low Resolution Spectrograph (LRS) as mentioned in this paper is the first HET facility instrument with a 13-slitlet Multi Object Spectroscopy (MOS) unit.
Abstract: The Hobby-Eberly Telescope (HET) is a revolutionary large telescope of 9.2 meter aperture, located in West Texas at McDonald Observatory. First light was obtained on December 11, 1996. The start of scientific operations is expected in the late summer of 1998. The Low Resolution Spectrograph [LRS, an international collaboration between the University of Texas at Austin (UT), the Instituto de Astronomia de la Universidad Nacional Autonoma de Mexico (IAUNAM), Stanford University, Ludwig-Maximillians-Universitat, Munich (USM), and Georg- August-Universitat, Gottingen (USG)] is a high throughput, imaging spectrograph which rides on the HET tracker at prime focus. The LRS will be the first HET facility instrument. The remote location and the tight space and weight constraints make the LRS a challenging instrument, built on a limited budget. The optics were partially constructed in Mexico at IAUNAM, the mechanics in Germany, and the camera and CCD system in Texas. The LRS is a grism spectrograph with three modes of operation: imaging, longslit, and multi-object. The field of view of the HET is 4 arcmin in diameter, and the LRS will have a 13-slitlet Multi Object Spectroscopy (MOS) unit covering this field. The MOS unit is based on miniature components and is remotely configurable under computer control. Resolving powers between R equals (lambda) /(Delta) (lambda) approximately 600 and 3000 with a 1 arcsecond wide slit will be achieved with a variety of grisms, of which two can be carried by the instrument at any one time. The CCD is a Ford Aerospace 3072 X 1024 device with 15 micrometer pixels, and the image scale is approximately 0.25 arcsec per pixel. Here we present a detailed description of the LRS, and provide an overview of the optical and mechanical aspects of its design (which are discussed in detail elsewhere in these proceedings). Fabrication, assembly, and testing of the LRS will be completed by mid 1998. First light for the LRS on the HET is expected in the summer of 1998.
174 citations
TL;DR: In this article, a volume-phase hologram based diffraction grating was proposed for astronomical spectroscopy applications, which shows promise of enhanced performance over surface-relief grating technology.
Abstract: A diffraction grating technology based upon volume-phase holograms shows promise of enhanced performance for many applications in astronomical spectroscopy over classical surface-relief grating technology. We present a discussion of the underlying physics of a volume-phase grating, give some theoretical performance characteristics, present performance data for a real volume-phase grating, and discuss some potential applications for this grating technology.
166 citations
TL;DR: In this paper, the authors present the history of the development, general aspects of the bolometer arrays, including the coupling to the telescope, and the status of work in progress at the Max-Planck-Institut fur Radioastronomie (MPIfR).
Abstract: Continuum radiometers based on bolometers have a long tradition at the Max-Planck-Institut fur Radioastronomie (MPIfR) in Bonn, Germany. Arrays of bolometers have been under development since the early 90s. A small 7-element system, operating at 300 mK, saw first light in 1992 at the IRAM 30 m- telescope and has been used successfully by numerous observers at that facility since then. While this array had a conventional 'composite' design, it was obvious that larger arrays, especially for higher frequencies, could take advantage of microfabrication technology. The recent MPIfR bolometer arrays employ a hybrid approach. They combine a single-mode horn array with a planar bolometer array on a single crystal Silicon wafer with Silicon-Nitride membranes. With efficient absorbing structures, the bolometers couple to the single mode of the radiation field collected by the horns, without needing integrating cavities. Readout is provided by NTD-Germanium thermistors that are attached to the absorbers. This paper covers the history of this development, the general aspects of the bolometer arrays, including the coupling to the telescope, and the status of work in progress.
164 citations
TL;DR: Phoenix as mentioned in this paper is an echelle spectrograph of the near-Littrow over-under configuration without cross dispersion for the 1-5 micrometers region, which is available at CTIO, KPNO, and Gemini.
Abstract: We describe a cryogenic, high-resolution spectrograph (Phoenix) for the 1-5 micrometers region. Phoenix is an echelle spectrograph of the near-Littrow over-under configuration without cross dispersion. The foreoptics include Lyot re- imaging, discrete and circular variable order sorting filters, a selection of slits, and optics for post-slit and Lyot imaging. The entire instrument is cooled to 50 K using two closed cycle coolers. The detector is a Hughes-Santa Barbara 512 X 1024 InSb array. Resolution of 65,000 has been obtained. Throughput without slit losses is 13 percent at 2.3 micrometers . Recent results are discussed. Phoenix is a facility instrument of the National Optical Astronomy Observatories and will be available at CTIO, KPNO, and Gemini.
124 citations
TL;DR: A high resolution near IR camera (CONICA) for the firs VLT unit is under development, which will provide diffraction limited spatial resolution being combined with the adaptive optics system NAOS.
Abstract: A high resolution near IR camera (CONICA) for the firs VLT unit is under development, which will provide diffraction limited spatial resolution being combined with the adaptive optics system NAOS. CONICA serves as a multi-mode instrument for the wavelength region between 1.0 and 5.0 micrometers , offering broad band, narrow band or Fabry Perot direct imaging capabilities, polarimetric modes using Wollaston prism or wire grid analyzers and long slit spectroscopy up to a spectral resolution of about 1000 per two pixel. We presented a first concept of CONICA in 1995. In the mean time, large parts of the instrument have been manufactured, the cryostat and the adapter have been finished and first cryogenic test have been performed. This paper describes the actual design and status of development of CONICA focusing on those aspects which have not been described in detail before or the design of which have been changed in the mean time.
124 citations
TL;DR: The design of the blue channel grisms have been optimized for maximum blaze efficiency, the highest dispersion grism having a groove density of 1200 gr/mm as discussed by the authors, and the optical design of LRIS-B camera uses fused silica and calcium fluoride elements, and includes a decentered meniscus element to compensate for coma introduced by the LRIS off-axis paraboloid collimator.
Abstract: This paper summarizes the optical, mechanical, electrical, and software design of LRIS-B, the blue channel of the Keck Low Resolution and Imaging Spectrograph. The LRIS-B project will shortly be completing the existing LRIS instrument through the addition of dichroic beamsplitters, grisms to disperse light on the blue channel, broad-band u, B, and V photometric filters, a blue and near-UV transmitting camera lens, and a large format blue-sensitive CCD detector. LRIS-B will also introduce piezoelectric xy-actuation of the CCD detector inside its Dewar, in order to compensate for flexure in the existing instrument; ultimately the red-side CCD detector will be similarly equipped, its PZT xy-stage being independently programmed. The optical design of the LRIS-B camera uses only fused silica and calcium fluoride elements, and includes a decentered meniscus element to compensate for coma introduced by the LRIS off-axis paraboloid collimator. The design of the blue channel grisms have been optimized for maximum blaze efficiency, the highest dispersion grism having a groove density of 1200 gr/mm. Optical elements not in use at any given time will be stowed in carousels externally mounted to the instrument sidewalls. The entire instrument is designed to permit remote operation.
111 citations
TL;DR: Bolocam as mentioned in this paper, a bolometric camera for millimeter-wave observations at the Caltech Submillimeter Observatory, has 144 diffraction-limited detectors operating at 300 mK, an 8 arcminute field of view, and a sky noise limited NEFD of approximately 35 mJy Hz-1/2 per pixel at (lambda) equals 1.4 mm.
Abstract: We describe the design of Bolocam, a bolometric camera for millimeter-wave observations at the Caltech Submillimeter Observatory. Bolocam will have 144 diffraction-limited detectors operating at 300 mK, an 8 arcminute field of view, and a sky noise limited NEFD of approximately 35 mJy Hz-1/2 per pixel at (lambda) equals 1.4 mm. Observations will be possible at one of (lambda) equals 1.1., 1.4, or 2.1 mm per observing run. The detector array consists of sensitive NTD Ge thermistors bonded to silicon nitride micromesh absorbers patterned on a single wafer of silicon. This is a new technology in millimeter-wave detector array construction. To increase detector packing density, the feed horns will be spaced by 1.26 f(lambda) (at (lambda) equals 1.4 mm), rather than the conventional 2 f(lambda) . DC stable read out electronics will enable on-the-fly mapping and drift scanning. We will use Bolocam to map Galactic dust emission, to search for protogalaxies, and to observe the Sunyaev- Zel'dovich effect toward galaxy clusters.
104 citations
TL;DR: FEROS as discussed by the authors is a fiber-fed bench-mounted prism cross-dispersed echelle spectrograph for the ESO 1.52m telescope at the European Southern Observatory (ESO) in La Silla, Chile.
Abstract: FEROS is a new fiber-fed bench-mounted prism crossdispersed echelle spectrograph for the ESO 1.52-m telescope at the European Southern Observatory (ESO) in La Silla, Chile. It works with a 79 lines/mm R2 echelle grating in quasi-Littrow mode and in white pupil configuration. With two fibers of 100 micrometer core diameter for the object and the nearby sky, the complete optical spectrum from 370 - 860 nm is recorded in one single exposure on a 2k X 4k thinned CCD with 15 micrometer pixels. Therefore, the instrument can work in a fixed configuration on the optical bench without movable parts besides the CCD shutter mechanics. For the highest-possible opto-mechanical stability. FEROS will be housed in a temperature and humidity controlled room in the former Coude room of the telescope. The resolving power of R equals 48,000 is reached by the use of a newly designed two-slice image slicer which is fed by the two fibers. Alternatively, the sky fiber can be illuminated with a calibration lamp during the whole object exposure to monitor the spectrograph's residual motions for high-precision radial-velocity work. FEROS is built for ESO by a consortium of four European astronomical institutes under the leadership of the Landessternwarte Heidelberg, Germany. Further members of the consortium are the Astronomical Observatory Copenhagen, Denmark, the Institut d'Astrophysique de Paris, and the Observatoire de Paris/Meudon, France. It is planned that FEROS will be fully operational at the ESO 1.52-m telescope in December 1998 and will be available to the community in early 1999.
TL;DR: The LAMOST system as mentioned in this paper is a special reflecting Schmidt system that has an aperture of 4 m, f ratio of 5 and a 5 degree field of view, and the main optical axis is fixed on the meridian plane and tilted 25 degree(s) to the horizontal from south to north.
Abstract: The optical system of LAMOST is a special reflecting Schmidt system. It has an aperture of 4 m, f ratio of 5 and a 5 degree(s) field of view. The main optical axis is fixed on the meridian plane and tilted 25 degree(s) to the horizontal from south to north. The celestial objects were observed for 1.5 hours when they pass through the meridian. The reflecting Schmidt plane, MA, and the spherical mirror, MB, are segmented mirrors. MB is fixed on the foundation. The shape of the reflecting Schmidt plate has to be changed with different declination (delta) and in the tracking process. This is achieved with active optics. About 4000 optical fibers are planed to put on the focal surface. Some key technologies for LAMOST have been studied and presented in this paper: the calculation and testing method for thin mirror and segmented mirror active optics; the preliminary calculation and the experiment for active optics; the simulated calculation for optical image quality in 1.5 hours observation; a preliminary design of the alt-azimuth mounting and tracking system of MA.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this article, a novel approach to modeling Shack-Hartmann-based adaptive optics (AO) system which allow to easily predict their performance is presented. But this approach is limited to the Fourier domain.
Abstract: In this paper, we present a novel approach to modeling Shack-Hartmann-based adaptive optics (AO) system which allow to easily predict their performance. The idea is to start for the power spectral density (PSD) of the turbulent phase and to derive the PSD of the compensated phase by taking into account the various errors affecting the AO correction, which can be expressed analytically in the Fourier domain. Once the PSD of the compensated phase is known, the computation of the residual point spread function is straightforward.
TL;DR: The University of Florida is developing the mid-IR imager, called GatirCam, to be used primarily, but not solely, at the southern hemisphere Gemini telescope at Cerro Pachon, Chile as mentioned in this paper.
Abstract: The University of Florida is developing the mid-IR imager, called GatirCam, to be used primarily, but not solely, at the southern hemisphere Gemini telescope at Cerro Pachon, Chile. Key features of GatirCam are its fully reflective optics, its very high mechanical rigidity, and the fact that the associated electronics are very similar to those is in use successfully on similar instrumentation. Design studies for GatirCam indicate that it will meet or exceed all critical requirements of image quality and performance. A low-resolution spectroscopic mode is also currently under consideration for implementation in GatirCam.
TL;DR: This report will focus on the mechanical design aspects of the Mosaic Imager and the upgrade path to achieve the scientific requirements will be discussed.
Abstract: A new generation wide-field imager is being developed and will be put into service at sites in North and South America. Driven by the requirement for larger imaging areas and more pixels but limited by manufacturing process constraints, manufacturers are developing 2, 3, and 4-side buttable CCDs that can be tiled to achieve large imaging areas as opposed to developing a single large CCD. NOAO has designed, fabricated, and tested a wide-field imager called Mosaic that tiles 8 CCDs to produce an imaging area slightly greater than 123 mm X 123 mm. Several successful science observation runs have been completed using Mosaic at the KPNO Mayall 4 m and .9 m telescopes. A second Mosaic Wide-Field Imager is presently being manufactured and will be deployed at the CTIO Blanco 4 m telescope early next year. This report will focus on the mechanical design aspects of the Mosaic Imager and the upgrade path to achieve the scientific requirements will be discussed.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: INTEGRAL as mentioned in this paper is an optical fiber unit for performing 2D spectroscopy of extended objects at the 4.2 m William Herschel Telescope (WHT), which is mounted at the GHRIL Nasmyth focus together with newly built acquisition, guiding, and calibration units.
Abstract: INTEGRAL is an optical fiber unit for performing 2D spectroscopy of extended objects at the 4.2 m. William Herschel Telescope (WHT). It is mounted at the GHRIL Nasmyth focus together with newly built acquisition, guiding, and calibration units. It makes use of the specially designed fiber spectrograph WYFFOS. This system allows up to six bundles to be mounted simultaneously. It currently contains three science oriented fiber bundles, any one of which can be easily and quickly placed in the telescope beam. Their spatial resolution elements (fiber core diameters) are 0'.45, 0'.9, and 2'.7, respectively. Hence, depending on the prevailing seeing conditions the instrument can be easily optimized for the scientific program. INTEGRAL was successfully commissioned at the WHT during a six night period in July 1997. Here we will discuss its main characteristics.
TL;DR: Hectospec as mentioned in this paper is a robotic positioner that will position 300 optical fibers at the f/5 focus of the converted MMT and a bench mounted moderate-dispersion spectrograph.
Abstract: The Hectospec consists of a robotic positioner that will position 300 optical fibers at the f/5 focus of the converted MMT and a bench mounted moderate-dispersion spectrograph. Hectospec will be the first wide-field instrument to be used at the converted MMT and is now under construction at the Smithsonian Astrophysical Observatory. Commissioning at the converted MMT is scheduled for mid 1999, shortly after first light at the f/5 focus. The innovative features of the instrument are described, emphasizing recent developments.
TL;DR: SpeX as discussed by the authors is a medium-resolution 0.8-5.5 micrometers cryogenic spectrograph being built at the Institute for Astronomy, University of Hawaii, for the NASA IR Telescope Facility on Mauna Kea.
Abstract: SpeX is a medium-resolution 0.8-5.5 micrometers cryogenic spectrograph being built at the Institute for Astronomy, University of Hawaii, for the NASA IR Telescope Facility on Mauna Kea. SpeX was funded by the National Science Foundation in July 1994. First-light is expected in 1999. The primary scientific driver of the instrument is to provide maximum simultaneous wavelength coverage at a spectral resolving power which is well-matched to many planetary, stellar and galactic features, and which adequately separates sky emission lines and disperses sky spectral resolutions of R approximately 1000-2000 simultaneously across 0.9-2.5 micrometers , 2.0-4.2 micrometers , or 2.4- 5.5 micrometers . SpeX will use an Aladdin II 1024 X 1024 InSb array in its spectrograph and an Aladdin II 512 X 512 InSb array in its IR slit-viewer.
TL;DR: In this paper, an optical fiber positioning system for LAMOST (Large Sky Area Multi-Object Fiber Spectroscopy Telescope) is proposed, where each unit is specified with the position of its domain with polar coordinates by using its center point as reference.
Abstract: In present paper we have proposed an optical fiber positioning system for LAMOST (Large Sky Area Multi-Object Fiber Spectroscopy Telescope). In this system, the convex focal plate of the telescope (Its diameter is 1.75 m) is divided into about 4000 individual domains. Each domain contains a controllable unit which is named X-unit. Each unit is specified with the position of its domain with polar coordinates (the angle and the radius distance from the center) by using its center point as reference. Each X-unit can be moved smoothly by verifying the two parameters of polar coordinates. An optical fiber is hold with X-unit and introduced to spectroscope, thus the optical fiber can be moved anywhere within its designated circular domain at the convex focal surface. In addition, the circular domain are overlapped in a `honeycomb-like' arrangement to ensure that there are no blind spots on the convex focal surface, such as that the radius distance of the units is 25 mm, and the positioning range of the optical fibers is 30 mm, thus there will be no `blind areas'. The structural parameters of the X-unit could also be optimized to limit the directional error of the axis in a certain range. Each unit is driven by two stepping motors and mobilized by computer in a way to ensure that the units do not collide with each other. It is possible that very high or very low star densities in areas of the field of view may reduce the observational efficiency of the telescope. This should not a significant problem by using optimization of the observation program.
TL;DR: The FLUOR project as mentioned in this paper used a fiber recombination unit to transform a pair of independent 80 cm telescopes into a stellar interferometer, which was used as part of the instrumentation at the IOTA inter-ferometer on Mt Hopkins (Arizona).
Abstract: The FLUOR project started in 1991 with a prototype fiber recombination unit that transformed a pair of independent 80 cm telescopes into a stellar interferometer. An improved version of this unit is now used as part of the instrumentation at the IOTA interferometer on Mt Hopkins (Arizona). The system is based on fluoride glass single-mode waveguides (non polarization-preserving) for observations at infrared wavelengths between 2 and 2.4 μm. A triple coupler performs the coherent recombination of the beams and extracts two calibration signals. A passive polarization control is sufficient to maintain the interferornetric efficiency above 80 %, with variations of the order of a few percents from one night to the next. The combination FLUOR/JOTA now routinely provides stellar interferograms on baselines ranging between 5 and 38 m, with an accuracy of 1 % or better in the fringe visibility measurements.
TL;DR: The University of Hawaii adaptive optics program has scaled its previously successful 13 elements AO system to 36 actuators and named it Hokupa'a, meaning "immovable star" in Hawaiian as discussed by the authors.
Abstract: The University of Hawaii adaptive optics program has scaled its previously successful 13 elements AO system to 36 actuators and named it 'Hokupa'a', meaning 'immovable star' in Hawaiian. First light for Hokupa'a in early November of 1997, was on the Canada France Hawaii Telescope on Mauna Kea, an f/35, 3.35 meter telescope. Performance at the telescope has now been measured and compares favorably with that predicted theoretically. The extension to 36 elements has now allowed the system to give diffraction limited performance down to I band on stars as faint as 12.5 magnitude in median 0.7 arcsecond seeing on Mauna Kea. Like our previous system, extensive computer simulations were carried out to achieve the best possible match between the curvature WFS and the deformable curvature mirror.
TL;DR: The Palomar Testbed Interferometer (PTI) as mentioned in this paper is a dual-star interferometer that employs active fringe tracking in the infrared (2.0-2.4 μm) to monitor fringe phase.
Abstract: The Palomar Testbed Interferometer (PTI) is an infrared, phase-tracking interferometer in operation at Palomar Mountain since July 1995. It was funded by NASA for the purpose of developing techniques and methodologies for doing narrowangle astrometry for the purpose of detecting extrasolar planets. The instrument employs active fringe trackingin the infrared (2.0-2.4 μm) to monitor fringe phase. It is a dual-star interferometer; it is able to measure fringes on two separate stars simultaneously. An end-to-end heterodyne laser metrology system is used to monitor the optical path length of the starlight. Recently completed engineering upgrades have improved the initial instrument performance. These upgrades are:extended wavelength coverage, a single mode fiber for spatial filtering, vacuum pipes to relay the beams, accelerometers on the siderostat mirrors and a new baseline. Results of recent astrometry data indicate the instrument is approaching the astrometric limit as set by the atmosphere.
TL;DR: In this paper, light coupling into single-mode fibers was investigated for a wide range of seeing conditions with both uncorrected turbulence and various levels of correction by an adaptive optics system.
Abstract: Because they have demonstrated very high visibility accuracies and have greatly simplified conventional interferometric recombination devices, single-mode fibers are being seriously considered in several optical interferometry projects. This paper deals with light coupling into single-mode fibers. An analytical expression of the coupling efficiency is derived for the monochromatic case. Then, the effect of purely static aberrations is considered. Finally, coupling in the presence of atmospheric turbulence is investigated for long exposure times. Using temporal sequencies of turbulent wavefronts, simulations are performed for a wide range of seeing conditions with both uncorrected turbulence and various levels of correction by an adaptive optics system.
TL;DR: In this article, the authors explore the scientific case and the conceptual feasibility of giant filled aperture telescopes, in the light of science goals needing an order of magnitude increase in aperture size, and investigate the requirements (and challenges) these imply for possible technical options in the case of a 100 m telescope.
Abstract: We explore the scientific case and the conceptual feasibility of giant filled aperture telescopes, in the light of science goals needing an order of magnitude increase in aperture size, and investigate the requirements (and challenges) these imply for possible technical options in the case of a 100 m telescope. The 100-m f/6.4 telescope optical concept is of a four mirror design with segmented, spherical primary and secondary mirrors, and 8-m class aspheric tertiary and quaternary mirrors, providing a 3 arc minutes field of view. Building on the experience of the VLT and other large telescope projects, we investigate mirror fabrication issues, a possible mechanical solution, the requirements for the absolutely essential adaptive optics system and for the instrumentation package, and the implications for budget and schedule.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this paper, the authors developed arrays of bolometers based on silicon nitride micromesh absorbers for the Spectral & Photometric Imaging Receiver (SPIRE) on the Far Infra-Red and Submillimeter Space Telescope (FIRST).
Abstract: We are developing arrays of bolometers based on silicon nitride micromesh absorbers for the Spectral & Photometric Imaging Receiver (SPIRE) on the Far Infra-Red and Submillimeter Space Telescope (FIRST). The bolometers are coupled to a close-packed array of 1 f(lambda) feedhorns which views the primary mirror through a cooled aperture stop. Feedhorn-coupled bolometers minimize the detector area and throughput and have good optical efficiency. A 1 f(lambda) feedhorn array provides, higher mapping speed than a 2 f(lambda) feedhorn array and reduces the number of jitters required to produce a fully sampled map, but at the cost of more detectors. Individual silicon nitride micromesh bolometers are already able to meet the performance requirements of SPIRE. In parallel we are developing transition-edge detectors read out by SQUID current amplifier. The relatively large cooling power available at 300 mK enables the array to be coupled to a cold SQUID multiplexer, creating a monolithic fully multiplexed array and making large format arrays possible for SPIRE.
TL;DR: In this paper, the first fully cryogenic near-IR multi-object spectrometer, FLAMINGOS, was constructed for use from 9000 angstrom to 2.4 micrometers.
Abstract: We are constructing a fully cryogenic near-IR multi-object spectrometer for use from 9000 angstrom to 2.4 micrometers . When completed in the summer of 1999, FLAMINGOS will be the first fully cryogenic near-IR multi-object spectrometer and will thus allow efficient background limited operation through the entire H and K windows. Due to its very fast, wide field optical design FLAMINGOS is also an excellent survey imager being more than an order of magnitude more efficient than current and planned near-IR cameras. When used for multi- slit spectroscopy FLAMINGOS will be a factor of 50 to 100 more efficient than current near-IR spectrometers. FLAMINGOS can accept nay input beam slower than f/6. This makes it extremely versatile allowing use on a large number of telescopes. FLAMINGOS will have a large collimated space with a grism wheel and a filter wheel, providing multiple object near-IR survey spectroscopy at resolutions of 600 up to 2000. It will have a small separate cryogenic dewar with a cycling time less than 6 hours, which will hold 11 cryogenic multi-slit plates that are fabricated outside the dewar. This will allow multi-slit spectroscopy 50-100 objects simultaneously.
TL;DR: In this paper, the adaptive optics system to be installed at one of the Nasmyth foci of the very large telescope (VLT) will provide compensated image to the high angular resolution IR spectro-imaging camera which covers the 1-5 micrometers spectral bands.
Abstract: NAOS is the adaptive optics system to be installed at one of the Nasmyth foci of the very large telescope (VLT). It will provide compensated image to the high angular resolution IR spectro-imaging camera which covers the 1-5 micrometers spectral bands. our French consortium is the sub-contractor of ESO for the design, manufacturing, integration and test of NAOS. For bright sources, the specification is to reach 70 percent Strehl ratio under average seeing conditions. Two wavefront sensors, one in the visible spectral range and one in the near IR spectral range, will equip the adaptive optics system. We foresee to obtained the first light at the VLT unit telescope 1 in mid-2000.
TL;DR: The Submillimeter Common-User Bolometer Array (SCUBA) is a new continuum camera operating on the James Clerk Maxwell Telescope (JCMT) on Mauna Kea, Hawaii as discussed by the authors.
Abstract: The Submillimeter Common-User Bolometer Array (SCUBA) is a new continuum camera operating on the James Clerk Maxwell Telescope (JCMT) on Mauna Kea, Hawaii. It consists of two arrays of bolometric detectors; a 91 pixel 350/450 micron array and a 37 pixel 750/850 micron array. Both arrays can be used simultaneously and have a field-of-view of approximately 2.4 arcminutes in diameter on the sky. Ideally, performance should be limited solely by the photon noise from the sky background at all wavelengths of operation. However, observations at submillimeter wavelengths are hampered by 'sky-noise' which is caused by spatial and temporal fluctuations in the emissivity of the atmosphere above the telescope. These variations occur in atmospheric cells that are larger than the array diameter, and so it is expected that the resultant noise will be correlated across the array and, possibly, at different wavelengths. In this paper, we describe our initial investigations into the presence of sky-noise for all the SCUBA observing modes, and explain our current technique for removing it from the data.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: A fiber optic array called DensePak was built for the WIYN 3.5 meter telescope to provide a low-cost option for integral field spectroscopy as discussed by the authors, which was used successfully in several scientific programs where mapping of spectral characteristics of extended objects such as galaxies, planetary nebulae, and comets is desired.
Abstract: A fiber optic array, called DensePak, has been built for the WIYN 3.5 meter telescope located on Kitt Peak, Arizona. DensePak incorporated the use of existing instruments at WIYN to provide a low-cost option for integral field spectroscopy. The array consists of 91, 310 micrometer diameter fibers bonded into a 7 X 13 rectangle with fibers spaced at 400 micrometer center-to-center. The array provides spatial coverage on the sky of approximately 30 X 45 arc-seconds at the WIYN F/6.4 Nasmyth focus. The fiber bundle feeds the same bench spectrograph as that used for the Hydra multi-object spectrograph which provides many configuration options. DensePak has been used successfully in several scientific programs where mapping of spectral characteristics of extended objects such as galaxies, planetary nebulae, and comets is desired. The options of low to high resolution spectroscopy with DensePak allow two-dimensional spatial measurements of abundances, velocity kinematics, and line ratios to be obtained. Proven success of DensePak at WIYN has led to consideration of future upgrades to expand scientific capability through improved spatial resolution.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: The Hectochelle as mentioned in this paper is a fiber-fed, multi-object spectrograph for the post-conversion MMT which will take 255 simultaneous spectra at a resolution of 32,000 - 40,000.
Abstract: The Hectochelle will be a fiber-fed, multi-object spectrograph for the post-conversion MMT which will take 255 simultaneous spectra at a resolution of 32,000 - 40,000. The absolute efficiency, including optical fiber losses, is predicted to be 6% - 10%, depending on the position of a line within a diffractive order. In one hour, features with 60 mangstrom should be resolved in mR equals 18 stars with a signal to noise of 10.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.