iSHELL is 1.15-5.4 μm high spectral resolution spectrograph being built for the NASA Infrared Telescope Facility on
Mauna Kea, Hawaii. Dispersion is accomplished with silicon immersion gratings in order to keep the instrument small
enough to be mounted at the Cassegrain focus of the telescope. The white pupil spectrograph is designed to produce
resolving powers of up to R=70,000. Cross-dispersing gratings mounted in a tilt-able mechanism at the second pupil
allow observers to select different wavelength ranges and, in combination with a slit wheel and dekker mechanism, slit
lengths ranging from 5″ to 25″. One Teledyne 2048x2048 Hawaii 2RG array is used in the spectrograph, and one
Raytheon 512x512 Aladdin 2 array is used in a slit viewer for object acquisition, guiding, and imaging. About $4 million
in funding has been provided by NSF, NASA and the University of Hawaii. First light is expected in about 2015. In this
paper we discuss the science drivers, instrument design and expected performance.
We present a conceptual design for a Precision Radial Velocity Spectrograph (PRVS) for the Gemini telescope. PRVS is
a fibre fed high resolving power (R~70,000 at 2.5 pixel sampling) cryogenic echelle spectrograph operating in the near
infrared (0.95 - 1.8 microns) and is designed to provide 1 m/s radial velocity measurements. We identify the various
error sources to overcome in order to the required stability. We have constructed models simulating likely candidates
and demonstrated the ability to recover exoplanetary RV signals in the infrared. PRVS should achieve a total RV error of
around 1 m/s on a typical M6V star. We use these results as an input to a simulated 5-year survey of nearby M stars.
Based on a scaling of optical results, such a survey has the sensitivity to detect several terrestrial mass planets in the
habitable zone around nearby stars. PRVS will thus test theoretical planet formation models, which predict an abundance
of terrestrial-mass planets around low-mass stars.We have conducted limited experiments with a brass-board instrument
on the Sun in the infrared to explore real-world issues achieving better than 10 m/s precision in single 10 s exposures and
better than 5 m/s when integrated across a minute of observing.
We present a conceptual design for an innovative infrared cross-dispersed spectrograph for the NASA Infrared
Telescope Facility (IRTF) at Mauna Kea. This facility-class instrument will provide a resolving power of up to 80,000 at
1.2-2.5 μm and 67,000 at 3-5 μm with a minimum slit width of 0.25". The instrument employs a silicon immersion
grating in order to reduce the size of the instrument. The design incorporates a 2048×2048 infrared array for the
spectrograph and an infrared slit viewer. The optical design is optimized for the thermal infrared (2.8-5.5 μm).
SpeX is a cross-dispersed medium-resolution 0.8-5.5 micron spectrograph in operation at the NASA Infrared Telescope Facility
(IRTF) on Mauna Kea, Hawaii. The instrument uses prism cross-dispersers and gratings to provide resolving powers of up to
R~2000 simultaneously across 0.8-2.4 micron or ~2-5.4 micron. An autonomous infrared slit-viewer is used for object acquisition,
guiding, and scientific imaging. The spectrograph employs a 1024x1024 Aladdin 3 InSb array and the imager a 512x512 Aladdin 2 InSb array. Since it was commissioned in June 2000, SpeX has been used for about 45% of all telescope time. We give an overview of the design, followed by details of the use and performance of the Aladdin arrays,
observing techniques, maintenance issues and lessons learned.
The design of the Redstar3 array control system including operational requirements and performance is presented. The architecture is intended to support next generation large format infrared/optical arrays and mosaics by using a new scalable approach that takes advantage of commercially available electronics. Specifically, an approach of using a combination of high speed fiber links, networked PCs and Linux to replace the previous generation of VME based DSPs will be discussed in detail. The design will be used to control HAWAII-2RG (1-4.9μm 2Kx2K HgCdTe), Aladdin II and III (1-5 μm 1Kx1K InSb) arrays in facility class instruments for Gemini, NSO and IRTF. It is also intended to be the platform for high count curvature correction, waveform sense and control for adaptive optics.
The NASA Infrared Telescope Facility (IRTF) on Mauna Kea now offers observers the opportunity to carry out their observations remotely. They can choose to work from the mid-level station at Hale Pohaku, from a dedicated remote observing room at the Institute for Astronomy in Hilo, or from their home institution. As a test of our remote capabilities, observations have been successfully obtained by observers from an office at the Observatoire de Paris in Meudon, France. Their observing program utilized SpeX, the IRTF's low- to medium-resolution near-IR spectrograph and imager, to measure the 0.8-2.5 micron reflectance spectra of fast moving, near-Earth asteroids. All target acquisition, guiding, and instrument control was commanded from Meudon. We describe this observing campaign, and provide details about the techniques we have developed for remote observing.
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.
A 1-5 micrometers IR camera and spectrograph (IRCS) is described. The IRCS will be a facility instrument for the 8.2 m Subaru Telescope at Mauna Kea. It consists of two sections, a spectrograph and a camera section. The spectrograph is a cross-dispersed echelle that will provide a resolving power of 20,000 with a slit width of 0.15 arcsec and two-pixel sampling. The camera section serves as a slit viewer and as a camera with two pixel scales, 0.022 arcsec/pixel and 0.060 arcsec/pixel. Grisms providing 400-1400 resolving power will be available. Each section will utilize an ALADDIN II 1024 X 1024 InSb array. The instrument specifications are optimized for 2.2 micrometers using the adaptive optics and the tip-tilt secondary systems of the Subaru Telescope.
The NASA IRTF is building a multiple digital signal processor (DSP) based array electronics control system for SpeX, an NSF funded 1 to 5 micron medium resolution spectrograph. SpeX will use a 1024 X 1024 InSb array for spectroscopy and one 512 X 512 quadrant of another 1024 X 1024 InSb array for slit field viewing and IR guiding. An additional system is also being produce at the Institute for Astronomy for the SUBARU IR camera and spectrograph (IRCS). Plans for IRCS include the use of a 1024 X 1024 InSb array for spectroscopy and one 1024 X 1024 InSb array for IR imaging. This document will provide the instrument derived requirements, an overall system description, and some of the tradeoffs and technical choices made. The design for both system is an evolutionary upgrade of the current IRTF array control electronics system used in a 256 X 256 InSb based imager, a 256 X 256 InSb and 512 X 512 CCD in an echelle spectrograph, an 800 X 800 CCD based tiptilt correction system and a non-IRTF 128 X 128 Si:As BIB array based imager.
The IR camera and spectrograph (IRCS) a facility instrument for the 8.2m Subaru Telescope is being built at the University of Hawaii, Institute for Astronomy. IRCS will use a 1024 X 1024 InSb array for spectroscopy and another 1024 X 1024 InSb array for IR imaging. In a collaborative effort with the team members of SpX<SUP>2</SUP>, a test system has been fabricated for joint testing of 1024 X 1024 InSb ALADDIN II based arrays. This document is a preliminary report on the test results of the science grade array provided by the Subaru Telescope Project. It is a possible candidate for inclusion in IRCS.
We discuss the design and performance of a solid KRS-5 grism used in NSFCAM, a 1-5.5 micrometers facility IR camera at the NASA IR telescope Facility on Mauna Kea. The grism was built by Carl Zeiss, Jena-Germany, and cost 13,800 dollars. It is used with order-sorting filters in the L-, K- and H-bands, and provides a spectral resolution of R equals 280. We also discus the advantages and disadvantages of solid grisms over replica resin grisms, and illustrate the performance of the grism with some astronomical observations.
The infrared instrumentation plan for the Subaru telescope is described. Four approved infrared instruments and one test observation system are now in the construction phase. They are coronagraph imager using adaptive optics (CIAO), cooled mid- infrared camera and spectrograph (COMICS), infrared camera and spectrograph (IRCS), OH-airglow suppressor spectrograph (OHS) and mid-infrared test observation system (MIRTOS). Their performance goals and construction schedules are summarized. The plan for procurement and evaluation of infrared arrays required by these instruments is briefly described.
We have just recently commissioned a new 1.0-5.5 micrometers IR array camera for the NASA IR Telescope Facility based upon the Santa Barbara Research Center 256x256 InSb array. The primary features of this new instrument are three user-selected platescales, a variety fo fixed bandpass filters, 1 to 2% spectral resolution circular variable filters, coronagraph masks, polarization imaging capability, an optical guider/imager, and a grism. In this paper we briefly outline the design and performance of the camera system, describe some unique operating modes, and show some recent images.
The optical design of a general-purpose 1 to 5 micrometers cryogenic IR camera and spectrograph (IRCS) for the 8.2-m Subaru telescope is described. The camera section serves the essential purpose of a slit-viewer in order to permit efficient use of the spectrograph on faint objects. It will also serve as a multipurpose IR camera. The spectrograph section will have a resolving power of (lambda) /(Delta) (lambda) equals 660 to 1600. 1 to 2.5 micrometers or 3 to 5 micrometers will be observed in a single exposure by using gratings and cross-dispersing prism combinations. The slit length will be 3 to 5'. The camera section will have 3 pixel scales (0'.030, 0'.056, and 0'.125) that provide high spatial imaging, 1:1 imaging (high throughput), and `wide-field' (about 2' X 2'). The spectrograph section will have 2 pixel scales: 0'.05/pixel and 0'.125/pixel. The important features of the IRCS are: (1) Two pixel scales are available, one matched to the tip-tilt secondary and the other matched to the adaptive optics system. (2) Switching between imaging and spectroscopic modes is possible. Therefore observational programs can be optimized for the seeing, availability of guide stars, and weather conditions. (3) In some cases deep imaging can be undertaken while long exposures are made in the spectroscopic mode.
The design of a multipurpose 1 - 5.5 micrometers infrared camera (NSFCAM) for the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii, is described. The camera is built around the new 256 X 256 InSb array manufactured by Santa Barbara Research Center (SBRC) and incorporates a variety of observing modes to fulfill its role as a major facility instrument. These include three remotely-selectable image scales, a selection of fixed bandpass filters, R equals 50 - 100 spectral resolution circularly variable filters, a grism, coronographic masks, and a polarization imaging capability. Through the use of flexible array clocking schemes, driven by programmable digital signal processors (DSPs), we plan to implement several new operating modes, including real-time shift and add for image stabilization, and fast subarray readouts for occultations. Simultaneous optical and infrared imaging of the same field will be possible through the use of a cold dichroic beamsplitter. This feature is primarily intended for use with the IRTF tip-tilt image stabilization system currently being built. Given a suitable guide star, the camera should achieve near-diffraction limited imaging at 2 - 5 micrometers . In this paper we discuss the design of the optics, cryogenic, electronics and software needed to provide the camera with these capabilities.