The Gemini Remote Access to CFHT ESPaDONS Spectrograph has achieved first light of its experimental phase in May
2014. It successfully collected light from the Gemini North telescope and sent it through two 270 m optical fibers to the
the ESPaDOnS spectrograph at CFHT to deliver high-resolution spectroscopy across the optical region. The fibers gave
an average focal ratio degradation of 14% on sky, and a maximum transmittance of 85% at 800nm. GRACES achieved
delivering spectra with a resolution power of R = 40,000 and R = 66,000 between 400 and 1,000 nm. It has a ~8%
throughput and is sensitive to target fainter than 21st mag in 1 hour. The average acquisition time of a target is around 10 min. This project is a great example of a productive collaboration between two observatories on Maunakea that was
successful due to the reciprocal involvement of the Gemini, CFHT, and NRC Herzberg teams, and all the staff involved
closely or indirectly.
The Gemini Remote Access CFHT ESPaDOnS Spectrograph (GRACES) is an innovative instrumentation experiment
that will demonstrate if ESPaDOnS, a bench-mounted high-resolution optical spectrograph at CFHT, can be fed by a
270-m long fiber from the Gemini-North telescope with low enough losses to remain competitive with conventional
spectrographs on other 8 to 10-m telescopes. Detailed simulations have shown that GRACES should be more sensitive
than the HIRES spectrograph at Keck Observatory at wavelengths longer than about 600-700 nm. This result is possible
by using FPB-type of optical fibers made by Polymicro Technologies and by keeping the critical focal ratio degradation
(FRD) losses to less than 10%. Laboratory tests on these FPB optical fibers are underway and show that for 36-m lengths
that the FRD losses are as low as 0.8% with a repeatability of 1%. Tests are currently underway on 280-m lengths.
The instrument group of the Herzberg Institute of Astrophysics has been commissioned by the Gemini Observatory
to participate in a competitive conceptual design study for a new Gemini High-Resolution Optical Spectrograph
(GHOS). Concurrently this same group is working in partnership with both the Gemini and CFH Telescopes to
design the Gemini Remote Access to CFHT ESPaDOnS Spectrograph, (GRACES). Both these instruments will use
a fiber feed allowing light received by the Gemini telescope to be processed via remotely positioned instruments.
This paper will explore the similarities and differences in requirements, inherent challenges, concepts, design
solutions and areas of concept sharing.
The Gemini Observatory is going through an extraordinary time with astronomical instrumentation. New powerful
capabilities are delivered and are soon entering scientific operations. In parallel, new instruments are being planned and
designed to align the strategy with community needs and enhance the competitiveness of the Observatory for the next
decade. We will give a broad overview of the instrumentation program, focusing on achievements, challenges and
strategies within a scientific, technical and management perspective. In particular we will discuss the following
instruments and projects (some will have dedicated detailed papers in this conference): GMOS-CCD refurbishment,
FLAMINGOS-2, GeMS (MCAO system and imager GSAOI), GPI, new generation of A&G, GRACES (fiber feed to
CFHT ESPaDOnS) and GHOS (Gemini High-resolution Optical Spectrograph), and provide some updates about
detector controllers, mid-IR instruments, Altair, GNIRS, GLAO and future workhorse instruments.
The NASA Infrared Telescope Facility is engaged in a long-term program to improve the image quality of the telescope.
One element of the program is to minimize the static aberrations. The largest static aberration is spherical aberration,
although aberrations caused by zonal polishing rings and support-pad print-through on the primary mirror are also
significant. To correct these static wave front errors, a new secondary mirror is being fabricated with a custom, phase
compensating surface. Since the as-built optical specifications for the IRTF mirrors have been lost, a configurable multimode
instrument was fabricated for use at both the prime and Cassegrain foci to characterize the primary mirror and to
measure the wave front errors at both foci. The instrument modes include a focal plane camera, a knife-edge tester, a
pupil viewer, a Hartmann wave front sensor, a calibrator, and an on-axis guider. Test results from the prime focus show
that the primary mirror has an incorrect conic surface and is poorly supported, which results in a fixed amount of
spherical aberration and variable amounts of astigmatism, coma, and trefoil. Cassegrain focal plane results show that the
original secondary mirror mount system also induces aberrations. Two new secondary mirrors have been made and at
least one of the mirrors will have a custom surface, using ion beam polishing methods, to correct these static aberrations.
An analysis is presently underway to determine the optimum compensating surface to be applied by ion beam polishing.
The tenth anniversary of Gemini Observatory operation provides a convenient reference point to reflect on the past,
present, and future of the instrumentation program. The Observatory will soon meet a significant milestone: the last
batch of instruments from the first three generations of instrumentation development will be commissioned by the end of
2011. This will represent a revolution for Gemini-South, which will have a suite of new or upgraded, state of the art
instruments. Included in this suite will be extreme and multi-conjugate adaptive optics systems, new infrared imagers
and multi-object spectrographs, and state of the art CCD detectors. The Observatory is on the cusp of a new era with the
fourth generation of instrumentation. While the past represented building a whole new observatory, the future represents
renewal and reinvestment, with plans for a new high-resolution optical spectrograph, new acquisition and guide units,
upgraded and refurbished instruments, and improved methods for developing Gemini instrumentation.
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).
A feasibility design study was undertaken to assess the requirements of a mid-infrared echelle spectrograph (MIRES)
with a resolving power of 120,000 and its associated mid-infrared adaptive optics (MIRAO) system on the Thirty-Meter
Telescope. Our baseline design incorporates a 2K×2K Si:As array or array mosaic for the spectrograph and a 1K×1K
Si:As array for the slit viewer. Various tradeoffs were studied to minimize risk and to optimize the sensitivity of the
instrument. Major challenges are to integrate the spectrograph to the MIRAO system and, later, to an adaptive
secondary, the procurement of a suitable window and large KRS-5 lenses, and the acquisition of large format mid-IR
detector arrays suitable for the range of background conditions. We conclude that the overall risk is relatively low and
there is no technical reason that should prevent this instrument from being ready for use at first light on the Thirty-
Meter Telescope.
The Infrared Array Camera (IRAC) is one of three focal plane instruments on board the Spitzer Space Telescope. IRAC is a four-channel camera that obtains simultaneous broad-band images at 3.6, 4.5, 5.8, and 8.0 μm in two nearly adjacent fields of view. We summarize here the in-flight scientific, technical, and operational performance of IRAC.
The Infrared Array Camera (IRAC) is one of three focal plane instruments in the Space Infrared Telescope Facility (SIRTF). IRAC is a four-channel camera that obtains simultaneous images at 3.6, 4.5, 5.8, and 8 microns. Two adjacent 5.12 X 5.12 arcmin fields of view in the SIRTF focal plane are viewed by the four channels in pairs (3.6 and 5.8 microns; 4.5 and 8 microns). All four detectors arrays in the camera are 256 X 256 pixels in size, with the two shorter wavelength channels using InSb and the two longer wavelength channels using Si:As IBC detectors. We describe here the results of the instrument functionality and calibration tests completed at Goddard Space Flight Center, and provide estimates of the in-flight sensitivity and performance of IRAC in SIRTF.
The Space IR Telescope Facility (SIRTF) contains three focal plane instruments, one of which is the IR Array Camera (IRAC). IRAC is a four-channel camera that provides simultaneous 5.12 X 5.12 arcmin images at 3.6, 4.5, 5.8 and 8 microns. The pixel size is 1.2 arcsec in all bands. Two adjacent fields of view in the SIRTF focal plane are viewed by the four channels in pairs. All four detector arrays in the camera are 256 by 256 pixels in size, with the two short wavelength channels using InSb and the two longer wavelength channels using Si:As IBS detectors. The IRAC sensitivities at 3.6, 4.5, 5.8, and 8.0 microns are 6, 7, 36, and 54 microJanskys, respectively. Two of the most important scientific objectives of IRAC will be to carry out surveys to study galaxy formation and evolution during the early stage of the Universe, and to search for brown dwarfs and superplanets.
Two wide field, multiple beam, near IR cameras are being developed for the MMT and Whipple Observatories. For the MMT a triple beamed, 1024 X 1024 pixel camera for the 6.5-m f/5 is being designed. As a prototype for the MMT and for use on the Whipple Observatory 1.2-m telescope, a dual beamed, 256 X 256 InSb array camera with three selectable magnifications has been built and in use for the past year.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.