We describe the design, construction and measured performance of the Kitt Peak Ohio State Multi-Object Spectrograph
(KOSMOS) for the 4-m Mayall telescope and the Cerro Tololo Ohio State Multi-Object Spectrograph (COSMOS) for
the 4-m Blanco telescope. These nearly identical imaging spectrographs are modified versions of the OSMOS
instrument; they provide a pair of new, high-efficiency instruments to the NOAO user community. KOSMOS and
COSMOS may be used for imaging, long-slit, and multi-slit spectroscopy over a 100 square arcminute field of view with
a pixel scale of 0.29 arcseconds. Each contains two VPH grisms that provide R~2500 with a one arcsecond slit and their
wavelengths of peak diffraction efficiency are approximately 510nm and 750nm. Both may also be used with either a
thin, blue-optimized CCD from e2v or a thick, fully depleted, red-optimized CCD from LBNL. These instruments were
developed in response to the ReSTAR process. KOSMOS was commissioned in 2013B and COSMOS was
commissioned in 2014A.
The Multi-Object Double Spectrographs (MODS) are two identical high-throughput optical dichroic-split double-beam
low- to medium-dispersion CCD spectrometers being deployed at the Large Binocular Telescope (LBT). They operate in
the 3200-10500Å range at a nominal resolution of λ/δλ≈2000. MODS1 saw first-light at the LBT in September 2010,
finished primary commissioning in May 2011, and began regular partner science operations in September 2011. MODS2
is being readied for delivery and installation at the end of 2012. This paper describes the on-sky performance of MODS1
and presents highlights from the first year of science operations.
We present the design for the 340 Mpixel KMTNet CCD camera comprising four newly developed e2v CCD290-99
imaging sensors mounted to a common focal plane assembly. The high performance CCDs have 9k x 9k format, 10
micron pixels, and multiple outputs for rapid readout time. The camera Dewar is cooled using closed cycle coolers and
vacuum is maintained with a cryosorption pump. The CCD controller electronics, the electronics cooling system, and the
camera control software are also described.
The Multi-Object Double Spectrographs (MODS) are two identical high-throughput optical low- to medium-resolution
CCD spectrometers being deployed at the Large Binocular Telescope (LBT). Operating in the 340-1000nm range, they
use a large dichroic to split light into separately-optimized red and blue channels that feature reflective collimators and
decentered Maksutov-Schmidt cameras with monolithic 8×3K CCD detectors. A parallel infrared laser closed-loop
image motion compensation system nulls spectrograph flexure giving it high calibration stability. The two MODS
instruments may be operated together with digital data combination as a single instrument giving the LBT an effective
aperture of 11.8-meter, or separately configured to flexibly use the twin 8.4-meter apertures. This paper describes the
properties and performance of the completed MODS1 instrument. MODS1 was delivered to LBT in May 2010 and is
being prepared for first-light in September 2010.
The recently commissioned system for aluminizing the 8.408 meter diameter Large Binocular
Telescope mirrors has a variety of unusual features. Among them are aluminizing the mirror in the
telescope, the mirror is horizon pointing when aluminized, boron nitride crucibles are used for the
sources, only 28 sources are used, the sources are powered with 280 Volts at 20 kHz, high vacuum
is produced with a LN2 cooled charcoal cryo-panel, an inflatable edge seal is used to isolate the
rough vacuum behind the mirror from the high vacuum space, and a burst disk is mounted in the
center hole to protect the mirror from overpressure. We present a description of these features.
Results from aluminizing both primary mirrors are presented.
Ohio State is building two identical Multi-Object Double Spectrographs (MODS), one for each of the f/15 Gregorian foci of the Large Binocular Telescope (LBT). Each MODS is a high-throughput optical low- to medium-resolution CCD spectrometer operating in the 320-1000nm range with a 6.5-arcminute field-of-view. A dichroic distributes the science beam into separately-optimized red and blue channels that provide for direct imaging and up to 3 spectroscopic modes per channel. The identical MODS instruments may be operated together with digital data combination as a single instrument giving the LBT an effective aperture of 11.8-meter, or separately configured to flexibly use the twin 8.4-meter apertures. This paper describes progress on the integration and testing of MODS1, and plans for the deployment of MODS2 by the end of 2008 at the LBT.
We are building a Multi-Object Double Spectrograph for the Large Binocular Telescope. The instrument is designed to have high throughput from 320 to 1000 nm, spectral resolutions of 1,000-10,000, and multi-object capability over a 6 arcminute field. The design incorporates a dichroic and splits the science beam into a blue and a red channel, each of which can illuminate an 8,192 pixel long detector (with 15 micron pixels) with good image quality. The highly modular design can hold up to three gratings and an imaging flat and a selection of filters in each channel, all of which are quickly accessible; this allows for substantial observing flexibility. Progress on the construction of the instrument and future plans will be described.
We describe an instrument that is capable of taking simultaneous images at one optical (UBVRI) and one near-infrared (JHK) wavelength. The instrument uses relatively simple optics and a dichroic to image the same field on to an optical CCD and an HgCdTe array. The mechanical and thermal design is similar to previous instruments built by our group and the array controllers are based on the same architecture. The instrument has been in use for the past four years on the CTIO/Yale 1m telescope in Chile and has an excellent operational/reliability record. A number of notable science results have been obtained with the instrument; especially interesting are several photometric monitoring projects that have been possible, since the instrument is available every night on the telescope.
The ISL is a successful astronomical instrumentation program that has completed three major instruments and many smaller projects since 1987. We have developed the capabilities to perform all aspects of instrument design and construction and a range of unique skills and methods. We maintain a permanent staff that currently consists of two scientists specializing in optical design and detector systems, a seniors mechanical engineer, a programmer, an electronic engineer, a mechanical designer, two machinists, and a lab assistant. Instrumentation projects also draw upon faculty and graduate student effort.
The Ohio State Instrument Control and IMage ACquisition System, ICIMACS, is the computer hardware and software used by all instruments developed by the Imaging Science Laboratory (ISL) to control the detector, pre-process data, record image data on a separate computer system for data reduction and analysis, generate real time data display, control the mechanisms within an instrument, interface with the telescope controller, connect to a user interface, and perform engineering functions such as temperature or pressure logging. ICIMACS has now been used on 12 different instruments and is herein described as applied to 'MOSAIC' the near IR imager/spectrometer in use on the Kitt Peak 2.1 and 4 meter telescopes and on the MDM 2.4 and 1.3 meter telescopes.