mountain profile Institute for Astronomy University of Hawaii

Instrumentation Development

Maintained by LG

 

Infrared Array Detector Development

Don Hall and Klaus Hodapp have been developing a 16 megapixel infrared array called H4KRG-15, which has four times the pixels of the largest IR arrays previously available to astronomers.

It is designed primarily as a building block for the huge mosaic focal-plane arrays required by wide-field imaging with survey and 30 meter class telescopes.

 

 

 

First-light image of the galaxy M51 at a wavelength of 1.65 microns obtained with the H4KRG-15 infrared array detector at the UH 2.2 meter telescope.

 

 

 

 

 

 

Immersion Grating Spectrograph for the IRTF

Alan Tokunaga and John Rayner are leading an effort to design and build a 1—5 micron immersion grating spectrograph for the IRTF. The heart of the instrument is a silicon immersion grating that is being fabricated at the University of Texas at Austin as a collaborative effort. Since the dispersion occurs in the silicon material, the dispersion is n times larger than in vacuum, where n is the index of refraction. For silicon, n = 3.4, and this instrument is 3.4 smaller in linear dimensions than a conventional spectrograph, allowing it to be safely mounted on the IRTF.  The instrument is optimized for the study of molecules in planetary atmospheres, comets, stars, brown dwarfs, and the interstellar medium. Completion of the instrument will take another 3 years.

 

 

Adaptive Optics Development

`Imaka

Mark Chun and Christ Ftaclas have been developing advanced curvature adaptive optics systems and components and pushing to extend the field of view of ground-layer adaptive optics. The Hokupa‘a-85 curvature system is being developed and installed on the AEOS telescope on Haleakalā by Ftaclas and David Harrington. It will provide a testbed for high contrast imaging and polarimetry. The ‘IMAKA project led by Chun is working toward extremely large corrected fields of view at visible and near-infrared wavelengths. The teams extensive tests of the optical turbulence above Mauna Kea show that the corrected field of view of a ground-layer AO system can be pushed to nearly a degree. This is an areal field of view several orders of magnitude larger than previously considered and pushes adaptive optics into the realm of survey-science observations.

 

 

The ‘Imaka concept at the prime focus on the Canada-France-Hawaii telescope. The instrument combines ground-layer adaptive optics and orthogonal-transfer CCDs to provide high-resolution images (FWHM ~ 0.33") over a field of view approaching 0.7deg2.

 

SITELLE

Glenn Morrison is the project scientist of a new instrument for the Canada-France-Hawaii telescope (CFHT), SITELLE (Spectromètre Imageur à Transformée de Fourier pour l’Etude en Long et en Large de raies d’Emission). SITELLE will be an imaging Fourier transform spectrometer (IFTS) capable of obtaining the visible (350–950 nm) spectrum of every source of light in a field of view of 11 arcminutes, with 100% spatial coverage and a spectral resolution ranging from R = 1 (deep panchromatic image) to R > 10000 (for gas dynamics). SITELLE will cover a field of view 100 to 1000 times larger than traditional integral field spectrographs, such as GMOS-IFU on Gemini or the future MUSE on the VLT. It is the descendant of BEAR, the first IFTS installed on the CFHT and the successor of SpIOMM, a similar instrument attached to the 1.6-m telescope of the Observatoire du Mont-Mégantic in Québec. SITELLE will be used to study the structure and kinematics of HII regions and ejecta around evolved stars in the Milky Way, emission-line stars in clusters, abundances in nearby gas-rich galaxies, and the star formation rate in distant galaxies.

The design and construction work is being performed by ABB Analytical, a Québec-based company that specializes in Fourier transform spectrometers and optical sensors. Science lead, optical design, and its integration are done at Université Laval. The mechanical design and fabrication of the input and output ports at Université de Montréal, while CFHT takes charge of the detectors' enclosure and cooling system. The Primary Investigator for SITELLE is L. Drissen based at Université Laval.

 

Advanced Imaging Methods for Large-Aperture Telescopes

Modern astronomy will soon herald the arrival of telescopes with apertures of 30 meters or more. These behemoths will necessarily be equipped with the next generation of adaptive optics (AO) systems with large-format deformable mirrors to help compensate for image distortion caused by turbulence in Earth's atmosphere. Numerical image restoration methods will then be used to further improve the resolution of the observations. However, due to the extreme levels of turbulence that will be encountered at visible wavelengths (due to the size of the aperture and the small coherence length of the atmosphere at these wavelengths), even the combination of AO and numerical image restoration will be ineffective, and observations will have to be restrained to infrared wavelengths.

To address this shortcoming, the IfA's imaging group led by Stuart Jefferies and Douglas Hope is developing methods that can deal with these adverse conditions. The methods include partitioning the aperture, augmenting the observations with simultaneous observations from a nearby smaller aperture telescope, and using the AO system's wave-front sensor data along with a multilayer model of the atmosphere to constrain the restoration process. Numerical simulation of the application of these methods to problems related to space situational awareness shows that they should be able to extend our capability to deal with turbulence conditions that are approximately three times worse than current methods can effectively deal with.

 

Left: Simulated observation of the Hubble Space Telescope obtained with a 3.6 m aperture telescope through atmospheric turbulence with a Fried parameter of 9 cm at a frame rate of 500 Hz. Left center: Restoration using a conventional multiframe blind deconvolution algorithm. Right center: Restoration based on simultaneous observations from 1.6 m and 3.6 m telescopes. Right: Restoration obtained from 3.6 m data using simultaneous wave-front sensor data during the restoration. All restorations are based on 40 msec of data.

 

The ATLAS Project

The acronym "ATLAS" stands for Asteroid Terrestrial-Impact Last Alert System, The project, conceived by John Tonry, consists of a pair of comparatively small observatories 60 - 100 miles apart, that use parallax to search for asteroids on an imminent collision course with Earth.  Although it will not be as sensitive as Pan-STARRS, ATLAS will have a much wider field of view, and will be able to survey the whole sky twice a night.

At the same time as it is searching for killer asteroids, ATLAS will provide light curves with 1-hour resolution for all stars in the galaxy brighter than m=20, some billion light curves. A key scientific goal is to monitor 20,000 white dwarfs for eclipses from transiting planets, especially habitable, Earth-sized planets. ATLAS should also detect 10,000 supernovae per year out to a redshift of 0.1.

ATLAS is described in more detail on the website fallingstar.com.