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Small Business Innovations

Under a Small Business Innovation Research (SBIR) contract to Kennedy Space Center, EIC Laboratories invented a Raman Spectrograph with fiber optic sampling for space applications such as sensing hazardous fuel vapors and making on-board rapid analyses of chemicals and minerals. Raman spectroscopy is a laser-based measurement technique that provides through a unique vibrational spectrum a molecular 'fingerprint,' and can function in aqueous environments. EIC combined optical fiber technology with Raman methods to develop sensors that can be operated at a distance from the spectrographic analysis instruments and the laser excitation source. EIC refined and commercialized the technology to create the Fiber Optic Raman Spectrograph and the RamanProbe. Commercial applications range from process control to monitoring hazardous materials.

Source record↗

The Star Formation History of Orion and its Environs

During the period of performance, we have obtained the following observations and carried out the analysis of the Orion associations itemized below. Optical Photometry: The Quest camera that had been damaged by lightning on Sept. 2001 was reconfigured to use 10 chips and only 3 filters instead of the original 4 but retaining its spatial coverage of 2.3deg wide in declination. During the Winter and Fall 2002 observing campaigns, we obtained multifilter photometry using the Quest camera on the 1mt Schmidt of the Venezuelan National Observatory, to continue the survey of the Orion clouds. In the Winter 2002 season, we obtained photometry for 10 scans at DEC=+5, 7 scans at DEC=-5. Several additional scans at DEC=-3 were obtained during the Fall 2002 observing campaign. Slit spectroscopy of bright candidates: During 2002 spectra for some 235 candidate PMS stars were obtained with the FAST spectrograph at the SAO 1.5m telescope in Mt. Hopkins. These objects, all brighter than V=16, are located in two strips centered at DEC=+l and -5, and spanning from RA=5h-6h. The spectra are being analyzed. Multifiber spectroscopy: Spectroscopy for our fainter (V less than or equal to 16) candidates has not kept pace with our spectroscopy of brighter candidates, because of the delay in the commissioning of the Hectospec and Hectoechelle multi-object spectrographs at the new 6.5m MMT. We obtained some data with the Hydra spectrograph on the WIYN telescope: Feb 1-4, 2002. Time granted to the project: "A Large Scale Survey of the Low-Mass Young Population in the Orion OB1 Association" (P.I.: C. Briceno). Three half-nights (we used the first half of the night, the second half of the night was used with the Mini-Mosaic imager by another team). Only the first half night was clear. We observed 3 fields centered in a 2.3 deg wide strip centered at DEC=-1 and spanning RA=Sh to 6h. A total of 250 spectra were obtained for the same number of candidate PMS stars. Nov. 13-15, 2002. Time granted to the project "Cluster survey of protoplanetary disk evolution", (P.I.: A. Sicilia-Aguilar). Clear weather throughout. We obtained spectra for some 200 candidate PMS stars in 3 fields located in a 2.3 deg wide strip centered at DEC=+l and spanning from RA=5h20m to 5h35m. Data for both observing runs is partially reduced and is being analyzed. U photometry: During Nov.29-Dec.4, 2002 we were granted time with the 4-shooter CCD Mosaic Camera at the SAO 1.2m telescope, to obtain U-band photometry of a subset of the newly identified T Tauri stars in the strip centered at DEC=-1. This sample is composed of strong H(alpha) emitting PMS stars (Classical T Tauri stars) located mostly in the Orion OB lb association, around the Orion Belt area. Our data will be combined with our calibration of the U-band excess (Gullbring et al. 1998) to derive mass accretion rates. Because of bad weather we observed only 20 stars during 1.5 clear nights. Near IR photometry: During Dec. 14-19, 2002 we used the IR Camera on the SAO 1.2m telescope, to obtain L-band photometry of a set of 17 the newly identified Orion OB 1a and 1b stars, in order to look for IR excess emission coming from the hotter inner parts of circumstellar disks. Again, mediocre weather prevented a larger set to be observed. These stars were also observed with the OSCIR mid-IR camera on Gemini North during later 2001. Our goal is to construct SEDs from the visual out to the mid-IR (by combining our optical/IR data with 2MASS JHK magnitudes) in order to explore disk dissipation at the critical ages of 5-10 Myr spanned by these stars.

Calvet, Nuria↗

Narrow-band EUV Multilayer Coating for the MOSES Sounding Rocket

The Multi-order Solar EUV Spectrograph (MOSES) is a slitless spectrograph designed to study solar He II emission at 303.8 Angstroms, to be launched on a sounding rocket payload. One difference between MOSES and other slitless spectrographs is that the images are recorded simultaneously at three spectral orders, m = -1,0, +l. Another is the addition of a narrow-band multilayer coating on both the grating and the fold flat, which will reject out-of-band lines that normally contaminate the image of a slitless instrument. The primary metrics f a the mating were high peak reflectivity and suppression of Fe XV and XVI emission lines at 284 Angstroms and 335 Angstroms, respectively. We chose B4C/Mg2Si for our material combination since it provides better values for all three metrics together than the other leading candidates Si/Ir, Si/B4C or Si/SiC. Measurements of witness flats at NIST indicate the peak reflectivity at 303.6 is 38.5% for a 15 bilayer stack, while the suppression at 284 Angstroms, is 4.5x and at 335 Angstroms is 18.3x for each of two reflections in the instrument. We present the results of coating the MOSES flight gratings and fold flat, including the spectral response of the fold flat and grating as measured at NIST's SURF III and Brookhaven's X24C beamline.

Owens, Scott M.↗

Remote Pulsed Laser Raman Spectroscopy System for Detecting Qater, Ice, and Hydrous Minerals

For exploration of planetary surfaces, detection of water and ice is of great interest in supporting existence of life on other planets. Therefore, a remote Raman spectroscopy system was demonstrated at NASA Langley Research Center in collaboration with University of Hawaii for detecting ice-water and hydrous minerals on planetary surfaces. In this study, a 532 nm pulsed laser is utilized as an excitation source to allow detection in high background radiation conditions. The Raman scattered signal is collected by a 4-inch telescope positioned in front of a spectrograph. The Raman spectrum is analyzed using a spectrograph equipped with a holographic super notch filter to eliminate Rayleigh scattering, and a holographic transmission grating that simultaneously disperses two spectral tracks onto the detector for higher spectral range. To view the spectrum, the spectrograph is coupled to an intensified charge-coupled device (ICCD), which allows detection of very weak Stokes line. The ICCD is operated in gated mode to further suppress effects from background radiation and long-lived fluorescence. The sample is placed at 5.6 m from the telescope, and the laser is mounted on the telescope in a coaxial geometry to achieve maximum performance. The system was calibrated using the spectral lines of a Neon lamp source. To evaluate the system, Raman standard samples such as calcite, naphthalene, acetone, and isopropyl alcohol were analyzed. The Raman evaluation technique was used to analyze water, ice and other hydrous minerals and results from these species are presented.

Garcia, Christopher S.↗

First Results from EUNIS-06

The Extreme Ultraviolet Normal-Incidence Spectrograph (EUNIS) sounding rocket experiment successfully completed its first flight on 12 April 2006 from White Sands Missile Range, obtaining 145 science images in each of two wavelength channels. EUNIS is designed to investigate the energetics of the solar corona and hotter transition region through high-resolution imaging spectroscopy with a rapid (2-3 second) cadence. The two independent optical systems of EUNIS simultaneously record spectra over two passbands (170-205 Angstroms and 300-370 Angstroms), each spatially resolved along slit lengths of about 660 arcsec. The longwave channel includes He II 304 Angstroms and strong lines from Fe XI-XVI. The shortwave passband has a sequence of very strong Fe IX-XIII lines. Together, the EUNIS telescopes furnish a wide range of temperature and density diagnostics and enables underflight calibration of instrumental passbands on the SOHO, TRACE, Solar-B and STEREO missions. We present an overview of the science images from the first flight with emphasis on transient phenomena. The target was active region NOAA 10871 and adjacent quiet areas. Spectra were recorded with exposure times as short as 0.1 s, demonstrating that EUNIS is the most sensitive solar EUV spectrograph in operation, with over 100 times the throughput of its predecessor, the Solar Extreme ultraviolet Research Telescope and Spectrograph (SERTS). EUNIS is supported by the NASA Heliophysics Division's Solar & Heliospheric Physics Supporting Research and Technology and Low Cost Access to Space Program.

Rabin, Douglas M.↗

The Importance of High Spatial and Appropriate Spectral Resolution Spectroscopy

Many diverse astronomical sources are resolved with diffraction-limited large telescopes. Application of appropriate dispersion spectroscopy unveils much information on the physics of these objects ranging from gamma ray bursters in host galaxies, star-formation regions and central engines in nearby galaxies, structures in galactic nebulae, resolved binaries with mass exchange, extended winds of massive stars, protoplanetary systems, and comets, asteroids and planets within our own solar system. Active optics and interferometers coupled with spectrographs can provide near-diffraction-limited spectroscopy from the ground but only longward of one micron. Below one micron, and certainly below 6000A, we must turn to space-based large telescopes equipped with spectrographs capable of providing spatially diffraction-limited spectroscopy of astronomical sources. Examples will be presented from the HST/STIS, ground-based and other instruments on science that has been accomplished. Suggestions will be made of what might be possible, and limitations thereof, with future large monolithic, multiple mirror or interferometric telescopes equipped with spectrographs that would be matched to the diffraction limit of the telescope.

Gull, Theodore↗

EUNIS-07: First Look

The Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding rocket instrument is a two-channel imaging spectrograph that observes the solar corona with high spectral resolution and a rapid cadence made possible by unprecedented sensitivity. EUNIS flew for the first time on 2006 April 12 (EUNIS-06), returning over 140 science exposures at a cadence of 2.1 s; each exposure comprises six 1K x 1K active pixel sensor (APS) images, three for each wavelength channel (170-205 $\AA$ and 300-370 $\AA$). Analysis of EUNIS-06 data has so far shed new light on the nature of coronal bright points, cool transients, and coronal loop arcades and has enabled calibration updates for TRACE and SOHO's CDS and EIT. EUNIS flew successfully again on 2007 November 6 (EUNIS-07). Because the APS's were operated in video rather than snapshot mode, a faster cadence of 1.3 s was possible (97% duty cycle), resulting in 276 science exposures. We present an overview of the EUNIS-07 spectra and describe the coordinated observing program executed by the Hinode Extreme ultraviolet Imaging Spectrograph (EIS) that will, in conjunction with the absolute radiometric calibration of EUNIS-07, result in the first on-orbit radiometric calibration of EIS. EUNIS data are freely available to the solar physics community. EUNIS is supported by the NASA Heliophysics Division through its Low Cost Access to Space Program in Solar and Heliospheric Physics.

Rabin, Douglas M.↗

The Hubble Space Telescope: UV, Visible, and Near-Infrared Pursuits

The Hubble Space Telescope continues to push the limits on world-class astrophysics. Cameras including the Advanced Camera for Surveys and the new panchromatic Wide Field Camera 3 which was installed nu last year's successful servicing mission S2N4,o{fer imaging from near-infrared through ultraviolet wavelengths. Spectroscopic studies of sources from black holes to exoplanet atmospheres are making great advances through the versatile use of STIS, the Space Telescope Imaging Spectrograph. The new Cosmic Origins Spectrograph, also installed last year, is the most sensitive UV spectrograph to fly io space and is uniquely suited to address particular scientific questions on galaxy halos, the intergalactic medium, and the cosmic web. With these outstanding capabilities on HST come complex needs for laboratory astrophysics support including atomic and line identification data. I will provide an overview of Hubble's current capabilities and the scientific programs and goals that particularly benefit from the studies of laboratory astrophysics.

Wiseman, Jennifer↗

Multipurpose Hyperspectral Imaging System

A hyperspectral imaging system of high spectral and spatial resolution that incorporates several innovative features has been developed to incorporate a focal plane scanner (U.S. Patent 6,166,373). This feature enables the system to be used for both airborne/spaceborne and laboratory hyperspectral imaging with or without relative movement of the imaging system, and it can be used to scan a target of any size as long as the target can be imaged at the focal plane; for example, automated inspection of food items and identification of single-celled organisms. The spectral resolution of this system is greater than that of prior terrestrial multispectral imaging systems. Moreover, unlike prior high-spectral resolution airborne and spaceborne hyperspectral imaging systems, this system does not rely on relative movement of the target and the imaging system to sweep an imaging line across a scene. This compact system (see figure) consists of a front objective mounted at a translation stage with a motorized actuator, and a line-slit imaging spectrograph mounted within a rotary assembly with a rear adaptor to a charged-coupled-device (CCD) camera. Push-broom scanning is carried out by the motorized actuator which can be controlled either manually by an operator or automatically by a computer to drive the line-slit across an image at a focal plane of the front objective. To reduce the cost, the system has been designed to integrate as many as possible off-the-shelf components including the CCD camera and spectrograph. The system has achieved high spectral and spatial resolutions by using a high-quality CCD camera, spectrograph, and front objective lens. Fixtures for attachment of the system to a microscope (U.S. Patent 6,495,818 B1) make it possible to acquire multispectral images of single cells and other microscopic objects.

Mao, Chengye↗

Sodium Velocity Maps on Mercury

The objective of the current work was to measure two-dimensional maps of sodium velocities on the Mercury surface and examine the maps for evidence of sources or sinks of sodium on the surface. The McMath-Pierce Solar Telescope and the Stellar Spectrograph were used to measure Mercury spectra that were sampled at 7 milliAngstrom intervals. Observations were made each day during the period October 5-9, 2010. The dawn terminator was in view during that time. The velocity shift of the centroid of the Mercury emission line was measured relative to the solar sodium Fraunhofer line corrected for radial velocity of the Earth. The difference between the observed and calculated velocity shift was taken to be the velocity vector of the sodium relative to Earth. For each position of the spectrograph slit, a line of velocities across the planet was measured. Then, the spectrograph slit was stepped over the surface of Mercury at 1 arc second intervals. The position of Mercury was stabilized by an adaptive optics system. The collection of lines were assembled into an images of surface reflection, sodium emission intensities, and Earthward velocities over the surface of Mercury. The velocity map shows patches of higher velocity in the southern hemisphere, suggesting the existence of sodium sources there. The peak earthward velocity occurs in the equatorial region, and extends to the terminator. Since this was a dawn terminator, this might be an indication of dawn evaporation of sodium. Leblanc et al. (2008) have published a velocity map that is similar.

Potter, A. E.↗

GESE: A Small UV Space Telescope to Conduct a Large Spectroscopic Survey of Z-1 Galaxies

One of the key goals of NASA's astrophysics program is to answer the question: How did galaxies evolve into the spirals and elliptical galaxies that we see today? We describe a space mission concept called Galaxy Evolution Spectroscopic Explorer (GESE) to address this question by making a large spectroscopic survey of galaxies at a redshift, z is approximately 1 (look-back time of approximately 8 billion years). GESE is a 1.5-meter space telescope with an ultraviolet (UV) multi-object slit spectrograph that can obtain spectra of hundreds of galaxies per exposure. The spectrograph covers the spectral range, 0.2-0.4 micrometers at a spectral resolving power, R approximately 500. This observed spectral range corresponds to 0.1-0.2 micrometers as emitted by a galaxy at a redshift, z=1. The mission concept takes advantage of two new technological advances: (1) light-weighted, wide-field telescope mirrors, and (2) the Next- Generation MicroShutter Array (NG-MSA) to be used as a slit generator in the multi-object slit spectrograph.

galaxy evolution↗

Experimental Estimation of CLASP Spatial Resolution: Results of the Instrument's Optical Alignment

The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) is a sounding-rocket experiment currently being built at the National Astronomical Observatory of Japan. This instrument aims to probe for the first time the magnetic field strength and orientation in the solar upper-chromosphere and lower-transition region. CLASP will measure the polarization of the Lyman-Alpha line (121.6nm) with an unprecedented accuracy, and derive the magnetic field information through the Hanle effect. Although polarization accuracy and spectral resolution are crucial for the Hanle effect detection, spatial resolution is also important to get reliable context image via the slit-jaw camera. As spatial resolution is directly related with the alignment of optics, it is also a good way of ensuring the alignment of the instrument to meet the scientific requirement. This poster will detail the experiments carried out to align CLASP's optics (telescope and spectrograph), as both part of the instrument were aligned separately. The telescope was aligned in double-pass mode, and a laser interferometer (He-Ne) was used to measure the telescope's wavefront error (WFE). The secondary mirror tilt and position were adjusted to remove comas and defocus aberrations from the WFE. Effect of gravity on the WFE measurement was estimated and the final WFE derived in zero-g condition for CLASP telescope will be presented. In addition, an estimation of the spot shape and size derived from the final WFE will also be shown. The spectrograph was aligned with a custom procedure: because Ly-light is absorbed by air, the spectrograph's off-axis parabolic mirrors were aligned in Visible Light (VL) using a custom-made VL grating instead of the flight Ly- grating. Results of the alignment in Visible Light will be shown and the spot shape recorded with CCDs at various position along the slit will be displayed. Results from both alignment experiment will be compared to the design requirement, and will be combined in order to estimate CLASP spatial resolution after its alignment in visible light.

spatial resolution↗

Optical Alignment of the Chromospheric Lyman-Alpha SpectroPolarimeter using Sophisticated Methods to Minimize Activities under Vacuum

The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding-rocket instrument developed at the National Astronomical Observatory of Japan (NAOJ) as a part of an international collaboration. The in- strument main scientific goal is to achieve polarization measurement of the Lyman-alpha line at 121.56 nm emitted from the solar upper-chromosphere and transition region with an unprecedented 0.1% accuracy. For this purpose, the optics are composed of a Cassegrain telescope coated with a "cold mirror" coating optimized for UV reflection and a dual-channel spectrograph allowing for simultaneous observation of the two orthogonal states of polarization. Although the polarization sensitivity is the most important aspect of the instrument, the spatial and spectral resolutions of the instrument are also crucial to observe the chromospheric features and resolve the Ly- pro les. A precise alignment of the optics is required to ensure the resolutions, but experiments under vacuum conditions are needed since Ly-alpha is absorbed by air, making the alignment experiments difficult. To bypass this issue, we developed methods to align the telescope and the spectrograph separately in visible light. We will explain these methods and present the results for the optical alignment of the CLASP telescope and spectrograph. We will then discuss the combined performances of both parts to derive the expected resolutions of the instrument, and compare them with the flight observations performed on September 3rd 2015.

CLASP↗

Spectroscopic Characterisation of Microlensing Events: Towards a New Interpretation of OGLE-2011-BLG-0417

The microlensing event OGLE-2011-BLG-0417 is an exceptionally bright lens binary that was predicted to present radial velocity variation at the level of several km s1. Pioneer radial velocity follow-up observations with the UVES spectrograph at the ESOVLT of this system clearly ruled out the large radial velocity variation, leaving a discrepancy between the observation and the prediction. In this paper, we further characterise the microlensing system by analysing its spectral energy distribution (SED) derived using the UVES spectrum and new observations with the ARCoIRIS (CTIO) near-infrared spectrograph and the Keck adaptive optics instrumentNIRC2 in the J, H, and Ks-bands. We determine the mass and distance of the stars independently from the microlensing modelling. We find that the SED is compatible with a giant star in the Galactic bulge and a foreground star with a mass of 0.94 +/- 0.09 M solar mass at a distance of 1.07 +/- 0.24 kpc. We find that this foreground star is likely the lens. Its parameters are not compatible with the onespreviously reported in the literature (0.52 +/- 0.04 M solar mass at 0.95 +/- 0.06 kpc), based on the microlensing light curve. A thoughtful reanalysis of the microlensing event is mandatory to fully understand the reason of this new discrepancy. More importantly, this paper demonstrates that spectroscopic follow-up observations of microlensing events are possible and provide independent constraints on the parameters of the lens and source stars, hence breaking some degeneracies in the analysis. UV-to-NIR low-resolution spectrographs like X-shooter (ESOVLT) could substantially contribute to this follow-up efforts, with magnitude limits above all microlensing events detected so far.

microlensing event OGLE-2011-BLG-0417↗

Determining the Spectral Content of MOSES Images

The Multi-Order Solar Extreme Ultraviolet Spectrograph (MOSES) sounding rocket was launched from White Sands Missile Range on 2006 February 8th, to capture images of the Sun in the He ii 303.8 Å emission line. MOSES is a slitless spectrograph that forms images in multiple spectral orders simultaneously using a concave diffraction grating in an effort to measure line profiles over a wide field of view from a single exposure. Early work on MOSES data showed evidence of solar features composed of neither He ii 303.8 Å nor the nearby Si xi 303.3 Å spectral lines. We have built a forward model that uses cotemporal EIT images and the Chianti atomic database to fit synthetic images with known spectra to the MOSES data in order to quantify this additional spectral content. Our fit reveals a host of dim lines that alone are insignificant but combined contribute a comparable intensity to MOSES images as Si xi 303.3 Å. In total, lines other than He ii 303.8 Å and Si xi 303.3 Å contribute approximately 10% of the total intensity in the MOSES zero order image. This additional content, if not properly accounted for, could significantly impact the analysis of MOSES and similar slitless spectrograph data, especially those using a zero-order (undispersed) image. More broadly, this serves as a reminder that multilayer EUV imagers are sensitive to a host of weak contaminant lines.

Solar transition region↗

Initial On-Orbit Spectral Calibration of the PACE Ocean Color Instrument

The NASA Plankton, Aerosol, Cloud, and ocean Ecosystem (PACE) mission Project Science Team has used Ocean Color Instrument (OCI) measurements of Fraunhofer lines in spectra of sunlight reflected by the solar diffuser and measurements of atmospheric absorption bands in cloudtop and ocean spectra to characterize the spectral calibration of OCI on orbit. Multiple lines have been analyzed for both the ultraviolet to visible (UVVIS, 340−607 nm) and visible to near-infrared (VISNIR, 597−897 nm) grating spectrographs. The spectrographs yield hyperspectral observations with 5 nm bandwidths and 0.625 nm sampling intervals. The on-orbit observations have been compared with the prelaunch spectral calibration of OCI performed by the Goddard Laser for Absolute Measurement of Radiance (GLAMR) during thermal vacuum testing to track any changes in the calibration since launch. The calibration analyzed the line positions and strengths for the Fraunhofer lines for each spectrograph by comparing the solar spectra measured by OCI with predicted solar spectra derived from the solar reference spectrum and the BRDF of the solar diffuser, convolved with the OCI relative spectral responses. The calibration also compared the line positions of the atmospheric absorption bands with the model transmissions used by the PACE Project. The line position comparisons show that the root mean square (RMS) spectral difference between the measured and predicted spectra is 0.15 nm, the average spectral shift is 0.062 nm, and the residual spectral dispersion over the wavelength range of the Fraunhofer lines is 0.17 nm. All three estimates of the spectral accuracy of OCI meet the instrument functional requirement of a spectral accuracy of 0.5 nm and are well within the 0.625 nm sampling interval of the data. The line strength comparisons between measured and predicted spectra are essentially the same. These results show that the spectral calibration of OCI on orbit has not drifted since the prelaunch calibration of OCI by GLAMR and that the on-orbit spectral calibration of OCI is stable over time. These results also provide a baseline for monitoring the future spectral performance of OCI on orbit.

Radiometric Calibration↗

The Optical Design of CHARIS: An Exoplanet IFS for the Subaru Telescope

High-contrast imaging techniques now make possible both imaging and spectroscopy of planets around nearby stars. We present the optical design for the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS), a lenslet-based, cryogenic integral field spectrograph (IFS) for imaging exoplanets on the Subaru telescope. The IFS will provide spectral information for 138×138 spatial elements over a 2.07 arcsec × 2.07 arcsec field of view (FOV). CHARIS will operate in the near infrared (lambda = 1.15 − 2.5 micrometers) and will feature two spectral resolution modes of R is approximately 18 (low-res mode) and R is approximately 73 (high-res mode). Taking advantage of the Subaru telescope adaptive optics systems and coronagraphs (AO188 and SCExAO), CHARIS will provide sufficient contrast to obtain spectra of young self-luminous Jupiter-mass exoplanets. CHARIS will undergo CDR in October 2013 and is projected to have first light by the end of 2015. We report here on the current optical design of CHARIS and its unique innovations.

High Contrast Imaging↗

Mechanical Design of NESSI: New Mexico Tech Extrasolar Spectroscopic Survey Instrument

NESSI: the New Mexico Tech Extrasolar Spectroscopic Survey Instrument is a ground-based multi-object spectrograph that operates in the near-infrared. It will be installed on one of the Nasmyth ports of the Magdalena Ridge Observatory (MRO) 2.4-meter Telescope sited in the Magdalena Mountains, about 48 km west of Socorro-NM. NESSI operates stationary to the telescope fork so as not to produce differential flexure between internal opto-mechanical components during or between observations. An appropriate mechanical design allows the instrument alignment to be highly repeatable and stable for both short and long observation timescales, within a wide-range of temperature variation. NESSI is optically composed of a field lens, a field de-rotator, re-imaging optics, an auto-guider and a Dewar spectrograph that operates at LN2 temperature. In this paper we report on NESSI's detailed mechanical and opto-mechanical design, and the planning for mechanical construction, assembly, integration and verification.

exoplanet↗