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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 505 records · Page 28
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NASA NTRS1982

Spectroscopic observations of comets

Development of a spectrograph using a microchannel plate intensifier for observing faint comets is described. The spectrograph is capable of obtaining useful spectra of objects as faint as M(2) = 18. The increased guiding efficiency achieved by the optical coupling of the ISIT vidicon of the 154 cm telescope has resulted in a better signal to noise ratio. The ability to take a direct image of the comet aids in the interpretation of the spatial profile of the emissions. Spectra of comets Schwassmann-Wachmann 1, Bradfield, Encke, Tuttle, and Stephen-Oterma are discussed.

Source record↗
NASA NTRS1981

Ultraviolet spectroscopy of comets using sounding rockets, IUE and Spacelab

Information was obtained from the IUE observations as a result of the high spatial resolution capability of the IUE spectrographs and the ability to observe the comet over an extended range of heliocentric distance. The IUE spectrographs also have a high dispersion capability which so far has been used to obtain high resolution spectra of the OH and CS bands.

Feldman, P. D.↗
NASA NTRS1981

High-resolution ultraviolet solar observations from sounding rockets and Spacelab

High spatial (about 1 arcsec) and temporal (20 sec) resolution UV solar spectroscopy has been carried out by the Naval Research Laboratory from sounding rockets since 1975. The High Resolution Telescope and Spectrograph payload, consisting of a 300 mm diameter x 4500 mm focal length Cassegrain telescope and the tandem Woodsworth spectrograph, was used to make the observations. Using this instrument, a multitude of highly energetic phenomena can be observed in the chromosphere, transition zone, and corona. High-resolution photographs of the UV continuum at 1600 A, used to study the fine structure and evolution of the temperature minimum layer, show that because of its strong spatial and temporal intensity fluctuations, the 1600 A continuum emission comes from not only the temperature minimum, but a variety of temperature regimes. Similar spatial and temporal behavior is seen in lower chromospheric lines of Si I. Typical line profiles of the C IV 1550 A line illustrate the fine structure and dynamics of the transition zone; the mass and energy flux balance in this zone is also determined.

Brueckner, G. E.↗
NASA NTRS1984

Collecting Light From Point Images

Light from sources at varying positions brought to fixed opening. In telescope field divided into 10 strips, 10 pairs of optical fibers moved laterally and longitudinally to any required position in their assigned strips. Fixed ends of fibers arrayed in line at spectrograph entrance slit. Concept developed to enhance efficiency of spectrographs on astronomical telescopes.

Goss, W. C.↗
NASA NTRS1982

Space Telescope - Eye on the universe

The NASA Space Telescope, which is to be put into orbit by the Space Shuttle in 1985, is described with attention to the design characteristics and fabrication processes of its optics and the five scientific instruments that will be mounted at the focal plane, behind the primary mirror. The primary mirror is fabricated from Ultra Low Expansion Glass, weighed 907 kg as a blank and took three and a half years to grind and polish to a deviation of no more than 0.000025 mm from the ideal surface. The instruments carried are the Wide Field Planetary Camera, which employs CCD detectors, the Faint Object Camera, the Faint Object Spectrograph, for use at visible and UV wavelengths, the UV High Resolution Spectrograph for 1100-2300 A wavelengths, and the High Speed Photometer for the study of time-dependent brightness fluctuations.

Davies, J. K.↗
NASA NTRS1982

Multiple object fiber optic spectroscopy

The Steward Observatory of the University of Arizona employs short optical fiber lengths to bring light from galaxy images at the 2.3 m telescope's focus to a line along a spectrograph slit, thereby obtaining simultaneous spectra of many objects of the field of view. After describing this instrument, attention is given to the development of an improved version through which efficiency gains will be obtained by remotely positioning the fibers under computer control and by correctly matching fiber outputs to the spectrograph optics. A CCD will replace the presently employed image tube and photographic plate detector system, in order to permit sky subtraction, yield increased dynamic range, and provide more accurate wavelength calibration due to the detector's fixed format.

Hill, J. M.↗
NASA NTRS1984

Astronomical application of IR CID technology

A portable microcomputer data system was developed to test a 2 x 64-element Si:Bi charge injection device (CID) infrared detector array on the Lick Observatory Shane telescope. An existing 0.5 m spectrograph was used for the tests after modification, and a spectral resolution of 1000 was achieved. Slow device response, due to the low background conditions in the spectrograph were shown. Astronomical data were later obtained, and a device read noise on the order of a few hundred electrons was achieved. The signal to noise ratios of the resulting spectra were about a factor of five lower than what could have been achieved with discrete photoconductive detectors. It is concluded that the CID array is competitive for applications in backgrounds lower than those used in the tests.

Rank, D. M.↗
NASA NTRS1984

NASA-Texas Planetary Program

Astronomical observations performed at the McDonald Observatory were summarized. Various spectra obtained from Jupiter, Uranus, Saturn, Neptune, Pluto, Titan, Iapetus, and sundry asteroids were described briefly. Spectra taken of various comets using an IDS (Intensified Dissector Scanner) spectrograph on a 2.7 m telescope were reviewed. The Octicon, a linear array of eight 1872-element Reticon arrays that was installed in the 2.7 m coude spectrograph at the observatory, was described. The 2.7 m coude scanner, 2.7 m coude CCD (charge coupled device), and 2.7 m radial velocity spectrometer were mentioned.

Smith, H. J.↗
NASA NTRS1984

Instrumentation studies for FUSE-Columbus

Telescope and spectrograph design for the Columbus ultraviolet astronomy satellite are described. A 1m mirror two-piece glancing incidence telescope design is suggested. A classical Rowland spectrograph is potentially the only design with efficiencies great enough to deliver the 100 sqcm net collecting area specified from a manageable telescope.

Osantowski, J. F.↗
NASA NTRS1983

Ultraviolet high-resolution spectroscopy from the Space Telescope

The High Resolution Spectrograph is one of five scientific instruments which will be part of the Space Telescope observatory. The spectrograph was designed to take advantage of the imaging and pointing capabilities of the telescope to obtain ultraviolet spectra with spectral resolution comparable to large, ground-based coudeinstruments. Some of the results of the ground-based testing program will be described, along with applications of these properties to future science programs.

Ebbets, D. C.↗
NASA NTRS1983

A spectroscopic method for calibration of solar extreme ultraviolet instrumentation

A method of calibrating solar extreme ultraviolet spectrographs in space using coronal emission lines of known relative intensity is presented and demonstrated. This approach is useful for recalibrating orbiting instruments that may be subject to degradation during extended periods of operation. The calibration results are insensitive to the physical distribution of emitting plasma in any likely solar coronal source. It is suggested that this technique may be useful for calibration of spectrographs used in the study of laboratory plasmas.

Neupert, W. M.↗
NASA NTRS1983

The kinematics and structure of N63A and associated H II regions

Shull (1983) and Shull et al. (1982) discussed very high resolution spectrographic observations of bright knots in the filaments of the Cygnus Loop, IC 443, Puppis A, and Vela X supernova remnants (SNRs). Information on the small-scale thermal, turbulent, and bulk radial motions of the gas in these galactic remnants was obtained on the basis of an analysis of the spectral-line profiles. An analysis by Shull (1983) of N49, located in the Large Magellanic Cloud (LMC) is concerned with the large-scale structural and kinematic properties of N49 as it evolves in a cloudy interstellar medium (ISM). The present investigation represents the companion analysis of N63A, which is also a Type II SNR in the LMC. Echelle spectrograph observations indicate, for the first time, the large-scale kinematic and structural properties of the N63A system. They show clearly that the SNR, like N49, is evolving in a clumpy ISM.

Shull, P., Jr.↗
NASA NTRS1984

Comparison of variations in the visible and ultraviolet spectra of a Centauri

Short and long wavelength, high resolution IUE spectrographs of the He I spectrum variable star a Cen are the basis of the present equivalent width and central depth measurements of UV absorption lines. The period for cyclic intensity variations is determined by means of a four-parameter, least squares fit to a sinusoid. Other spectrographic and photometric intensity determinations of the He I 4026 A line are combined with the present data to yield a period of 8.81620 + or - 0.00006 days.

Fahey, R. P.↗
NASA NTRS1983

Space Telescope maintenance and refurbishment

The Space Telescope (ST) represents a new concept regarding spaceborne astronomical observatories. Maintenance crews will be brought to the orbital worksite to make repairs and replace scientific instruments. For major overhauls the telescope can be temporarily returned to earth with the aid of the Shuttle. It will, thus, be possible to conduct astronomical studies with the ST for two decades or more. The five first-generation scientific instruments used with the ST include a wide field/planetary camera, a faint object camera, a faint object spectrograph, a high resolution spectrograph, and a high speed photometer. Attention is given to the optical telescope assembly, the support systems module, aspects of mission and science operations, unscheduled maintenance, contingency orbital maintenance, planned on-orbit maintenance, ground maintenance, ground refurbishment, and ground logistics.

Trucks, H. F.↗
NASA NTRS1983

Planned observations of P/Halley with the Hopkins Ultraviolet Telescope on Space Shuttle

The Hopkins Ultraviolet Telescope (HUT) is an f/2 90-cm prime-focus telescope with an f/2 Rowland-circle spectrograph designed for far-ultraviolet spectrophotometry of faint astronomical sources. The wavelength range is 850-1850 A with an ultimate spectral resolution of 2 A, but for observations of solar-system objects the spectrograph is responsive, in second order, to wavelengths as short as 500 A. The HUT is one of three instruments to be carried on Space Shuttle in 1986 as part of an ultraviolet astronomy payload, and it is intended to use these instruments for observations of Halley during the encounters in March, 1986. In addition to its unique capability to observe at wavelengths shorter than 1150 A, the spectral region that includes the resonance transitions of the noble gases, the HUT is significantly more sensitive for observations of extended sources than either IUE or Space Telescope.

Feldman, P. D.↗
NASA NTRS1984

The Magneto-optical Filter, Working Principles and Recent Progress

The Magneto-Optical Filter is described which allows simultaneous magnetic and velocity measurements (in both imaging and non-imaging modes) without the need for a spectrograph. In this way the stability and alignment problems of the spectrograph are completely overcome. Its major advantages are: wavelength absolute reference and stability, high signal to noise ratio and independence of the transmission profile from the incidence angle of the solar beam. It is an imaging instrument allowing high wave number analysis in the solar oscillation spectrum and a continuous monitoring of the image position through the chromospheric facular structures. The apparatus in use at Mt. Wilson is assembled in a modular form. The most important part of it is a glass cell containing the sodium vapor. The filter is easy to use but the cell is not easy to construct in an optimal way. The technology is in progress both to use Na and K together and to prevent the windows from becoming coated during a long-term operation.

Cacciani, A.↗
NASA NTRS1985

The solar vector magnetograph of the Okayama Astrophysical Observatory

The vector magnetograph of the Okayama Astrophysical Observatory is fed to the 65 cm solar coude telescope with a 10 m Littrow spectrograph. The polarimeter put at the telescope focus analyzes the incident polarization. Photomultipliers (PMT) at the exit of the spectrograph pick up the modulated light signals and send them to the electronic controller. The controller analyzes frequency and phase of the signal. The analyzer of the polarimeter is a combination of a single wave plate rotating at 40 Hz and a Wallaston prism. Incident linear and circular polarizations are modified at four times and twice the rotation frequency, respectively. Two compensators minimize the instrumental polarization, mainly caused by the two tilt mirrors in the optical path of the telescope. The four photomultipliers placed on the wings of the FeI 5250A line give maps of intensity, longitudinal field and transverse field. The main outputs, maps of intensity, and net linear and circular polarizations in the neighboring continuum are obtained by the other two monitor PMTs.

Makita, M.↗