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NASA NTRS1982

The excitation and distribution of CO (J = 6-5) emission in the Orion Nebula

Observations of the 691-GHz (J = 6-5) transition of CO in the BN/KL region of Orion obtained in February 1981, at the IR Telescope Facility at Mauna Kea are reported. The system employs a heterodyne receiver with an overall noise temperature of 3900 K DSB at 432 microns, 64 5-MHz IF-filter-bank channels, and a chopping secondary with 120-arcsec excursion, and has 35-arcsec resolution. Sample data are presented graphically and analyzed using a rate equation and a kinetic model. A 35 x 45-arcsec core with hot broad plateau emission (antenna temperature 180 + or - 36 K) surrounded by an area of strong narrow-line 120-K emission is found. It is suggested that the plateau emission originates in a wide thin sheet after a shock wave, with H2 density at least 10 to the 6th/cu cm and gas kinetic temperature greater than 500 K.

Buhl, D.↗

NASA NTRS1983

The grains and gas in Comet Bowell 1980b

The importance of coordinating different types of observations of a comet is illustrated in terms of spectral data on Comet Bowell. Photometric data in 1980 indicated that OH emissions were occurring when the comet was still more than 4 AU from the sun. Further measurements were arranged with the IUE satellite, the photoelectric scanner at Cerro Tololo and the IR telescope on Mauna Kea. Several sizes of diaphragms were used in order to estimate variations with respect to aperture. Calculations were made to quantify the wavelengths observed as a function of the grains' cross-sections. The OH emission was confirmed by the spectrographic and photometric data. It is suggested that sufficient dark materials are present on the cometary surface to have enhanced the absorption of solar radiation to levels sufficient for heating and dissociating surface ice particles.

Dwek, E.↗

NASA NTRS1984

Far Infrared and Submillimeter Observations of the Giant Planets

Far infrared measurements of the effective temperatures of Jupiter, Saturn, Uranus and Neptune were made. The measurements presented here cover the range from 35-1000 micrometers in relatively narrow bands. The observations at lambda 350 micrometers were made at the 3m NASA Infrared Telescope Facility (IRTF) of the Mauna Kea Observatory; those at lambda 350 micrometer were made on the Kuiper Airborne Observatory (KAO). All observations of Saturn were made when the ring inclination to Earth was 1.7 deg assuring an unambiguous measurement of the flux from the disk itself. Mars was used as the calibration reference. The results represent a consistent set of calibration standards. In these measurements, it is assumed that sub b(lambda = 350 micrometers) = T sub (lambda 350 micrometers). Measurements have been made of roughly 50% of the total flux emitted by Jupiter, 65% by Saturn, and 92% by Uranus and Neptune. These measurements therefore permit a considerable reduction in the uncertainties associated with the bolometric thermal outputs of the planets. The effective temperatures (T sub e) and the ratios of emitted to absorbed solar radiation were calculated.

Loewenstein, R. F.↗

NASA NTRS1984

Instrumentation for Submillimeter Polarimetry

During the last two years three instruments were built and operated for detection of polarization in the submillimeter to millimeter wavelength bands. In principle, simply rotating a polarizing grid in front of the detector would be sufficient to determine the state of linear polarization. In practice severe systematic problems are found with this approach. Everything in the light path has potential for inducing polarization. The telescope, apertures in the lightpath, and the Winston light collectors all introduce systematic errors. (The polarization/depolarization induced by these devices is due to diffraction and the finite conductivity of the metals used). Two of the polarimeters are for use on the KAO; the third is for the IRTF on Mauna Kea. The airplane polarimeters, M1 and M2, were specifically designed to minimize the systematic errors. The ground based polarimeter uses our f/35 photometer with an external polarizing grid as the analyzer. With all three instruments the key to success is the data collector and analysis scheme.

Dragovan, M.↗

NASA NTRS1985

First Direct Detection of Clay Minerals on Mars

Magnesian clays or clay-type minerals were conclusively detected in the martian regolith. Near-IR spectral observations of Mars using the Mauna Kea 2.2-m telescope show weak but definite absorption bands near microns. The absorption band positions and widths match those produced by combined OH stretch and Mg-OH lattice modes and are diagnostic of minerals with structural OH such as clays and amphiboles. Likely candidate minerals include serpentine, talc, hectorite, and sponite. There is no spectral evidence for aluminous hydroxylated minerals. No distinct band occurs at 2.55 microns, as would be expected if carbonates were responsible for the 2.35 micron absorption. High-albedo regions such as Elysium and Utopia have the strongest bands near 2.35 microns, as would be expected for heavily weathered soils. Low-albedo regions such as Iapygia show weaker but distinct bands, consistent with moderate coatings, streaks, and splotches of bright weathered material. In all areas observed, the 2.35-micron absorption is at least three times weaker than would be expected if well-crystallized clay minerals made up the bulk of bright soils on Mars.

Singer, R. B.↗

NASA NTRS1985

Spectral Reflectance Studies of the Orientale Basin

Twelve near-infrared spectra were obtained at the Mauna Kea Observatory 2.2-m telescopy using the Planetary Geosciences Division indium antimonide spectrometer. These include spectra obtained for two fresh surfaces on the inner Rook ring, two fresh craters in the outer Rook Mts., and two inner Rook ring, two fresh craters in the outer Rook Mts., and two fresh 11-km. craters (Eichstadt G and H) which are located between the outer Rook ring and the Cordillera ring and exposed material from within the knobby facies of the Montes Rook Formation. In addition, spectra were collected for portions of the Maunder Formation. Special attention was paid to the spectra collected for six immature features within the Cordillers ring. Analyses of the 1-micron band positions and shapes as well as continuum slopes indicate that the spectra for craters in the knobby facies and in the outer Rook Mts., while differing in detail, exhibit many common spectral characteristics. These spectra represent relatively fresh highlands rocks dominated by abundant Fe-bearing plagioclase feldspar and Ca-poor orthopyroxene. Compositions ranging between noritic anorthosite and anorthositic norite are indicated.

Hawke, B. R.↗

NASA NTRS1984

Astronomical applications of the new Goddard Si:Bi 16 x 16 array camera system

An improved 4-18 micron array camera system has been developed at NASA Goddard Space Flight Center for astronomical protometry, using 16 x 16 Si:Bi (bismuth dope silicon) accumulation mode charge injection device (AMCID) with 256 active pixels. An astronomical observing program using this device has been carried out. The 16 x 16 device had sufficiently good sensitivity, uniformity and noise characteristics to be used for successful observations at the Steward Observatory Mt. Lemmon 60 and 61-inch telescopes in May 1983, and at the NASA Infrared Telescope Facility (IRTF) at Mauna Kea in August 1983. Initial results indicate that this detector has sensitivity and noise characteristics comparable to other devices from the same generation of Aerojet arrays.

Lamb, G.↗

NASA NTRS1985

Brief search for low-mass objects

Observations of the nearby white dwarfs EG 5 (van Maanen 2) and EG 290 obtained in the J, H, K, L, L-prime, and M bands using an RC1 photometer at the Cassegrain focus of the 3.3-m IR telescope at Mauna Kea on Dec. 2, 1983 are reported. The L-band fluxes are analyzed to search for low-mass companion objects, but none is found. Upper limits of Te = 850 K and L = 5 x 10 to the -6th solar luminosity are established for the putative companions of both dwarfs, corresponding to a mass of 0.027 solar mass or less for an age of 3 Gyr.

Krishna Kumar, C.↗

NASA NTRS1985

Submillimeter observations of evolved stars

Broadband submillimeter observations of thermal emission from several evolved stars have been obtained using the United Kingdom Infrared Telescope on Mauna Kea, Hawaii. The observations were carried out at an effective wavelength of 400 microns in order to estimate the mass loss rates in dust from the stars. Direct estimates of mass loss rates are in the range 10 to the -9th to 10 to the -6th solar mass/yr. Analysis of the spectrum of IRC + 10216 confirmed previous estimates of dust grain emissivity in the range 10-1000 microns. The infrared properties of IRC + 10216 are found to be similar to the carbon rich object CRL 3068. No systematic difference was found between the dust masses of carbon rich and oxygen rich envelopes. The largest mass loss rates in dust were obtained for the bipolar objects OH 231.8 + 4.2 CRL 2688, CRL 618, and NGC 7027. It is suggested that the ratios of gas to dust, and the slopes of the far infrared to submillimeter wavelength continua of these stars objects are probably representative of amorphous rather than crystalline grains.

Sopka, R. J.↗

NASA NTRS1985

Photoelectric photometry of asteroid 69 Hesperia

UBV photometric observations of the M asteroid 69 Hesperia, obtained using single-channel photometers on the 31-in. and 42-in. reflectors at Lowell Observatory and on the 24-in. reflector at Mauna Kea Observatory during the apparition of August-November 1977, are reported. The data are presented in tables and graphs and analyzed. Findings presented include minimal temporal or phase-angle-dependent light-curve fluctuations, evidence for large-scale albedo variegation of a few percent, synodic rotation period 5.65537 + or - 0.00064 h, zero-phase color indices B-V = 0.68 mag and U-B = 0.24 mag, B-V phase reddening 0.003 mag/deg, and absolute zero-phase primary maximum magnitude V = 7.04.

Poutanen, M.↗

NASA NTRS1985

Spectral reflectance study of the Hadley-Appenine (Apollo 15) region

Twenty-three near infrared spectra were obtained from the Mauna Kea Observatory 2.2 m telescope. Results of an analysis of near infrared spectra obtained for surface units in the Hadley-Apennine region were presented. Compositional trends from the interior to exterior of the Imbrium are discussed.

Lucey, P. G.↗

NASA NTRS1985

A cryogenically cooled, multidetector spectrometer for infrared astronomy

A liquid helium-cooled, 24 detector grating spectrometer was developed and used for low resolution astronomical observations in the 5 to 14 micron spectral range. The instrument operated on the 91 cm Kuiper Airborne Observatory, the 3 m IRTF (Mauna Kea), the 3 m Shane telescope (Lick Observatory), and the 152 cm NASA and University of Arizona telescope. The detectors are discrete Si:Bi photoconductors with individual metal oxide semiconductor field effect transistor preamplifiers operating at 4 K. The system uses a liquid helium-cooled slit, order-sorter filter, collimator mirror, grating, and camera mirror arranged in a Czerny-Turner configuration with a cold stop added between the collimator mirror and the grating. The distances between components are chosen so that the collimator mirror images the secondary mirror of the telescope onto the cold stop, thus providing a very effective baffle. Scattered radiation is effectively reduced by using liquid helium-cooled, black baffles to divide the spectrometer into three separate compartments. The system noise-equivalent flux density, when used on the 152 cm telescope from 8 to 13 microns with a resolving power of 50, is 4.4 x 10 to the minus 17th power W/sq cm micron square root of Hz. The main applications are for measuring continuum radiation levels and solid state emission and absorption features in regions of star and planet formation.

Witteborn, F. C.↗

NASA NTRS1985

The dust coma of periodic Comet Churyumov-Gerasimenko (1982 VIII)

IR emission from the dust comet of Comet C-G was monitored at 1-20 microns with the 3-m NASA Infrared Telescope Facility at Mauna Kea, Hawaii during its perihelion passage from September 1982 to March 1983. The maximum dust production rate of approximately 200,000 g/sec was found to occur approximately one month after perihelion. It was also found that no obvious 1-micron silicate feature was present at 1.33 AU preperihelion, and that the ratio of dust/gas production was higher in other short-period comets observed in the infrared, particularly preperihelion. The low albedos derived for the dust grains (less than 0.05 micron) are noted to be plausible for mineral mixtures expected in cometary grains.

Hanner, M. S.↗

NASA NTRS1985

Observational tests for sulfur allotropes on Io

It has been established that, if the Io surface is primarily composed of sulfur allotropes, a change in reflectivity at certain wavelengths should be observable shortly after eclipse reappearance (ER). Four ERs were observed during July and August 1983 with a 61-cm telescope on Mauna Kea, Hawaii, and no posteclipse brightening effects in the filter bands selected for sensitivity to color changes in sulfur were found. The proposed model of the brightness change of elemental sulfur (S8) implies that this material covers less than 50 percent of the Io surface. It is concluded that no significant condensation of optically thick SO2 occurred on the Io surface during the four eclipses.

Hammel, H. B.↗

NASA NTRS1985

The 1983 June 15 occultation by Neptune. I - Limits on a possible ring system

Observations on 15 June 1983 of an occultation of a star by Neptune from Mauna Kea, Mount Stromlo, Siding Spring, and the Kuiper Airborne Observatory show no evidence for equatorial rings between 25,300 and 200,000 km (R/N/ = 25,269 km). Within most of this region, the upper limit on the optical depth along the line of sight, for rings broader than 6 km , is 0.04, which corresponds to a normal optical depth of 0.016. These results rule out a Neptunian ring system similar to that of Saturn or Uranus, but not a system of low optical depth similar to the Jovian rings. The data show no features that appear likely to have been caused by material in the equatorial plane of Neptune near the Roche limit.

Elliot, J. L.↗

NASA NTRS1985

20-micron transparency and atmospheric water vapor at the Wyoming Infrared Observatory

The atmospheric transparency at 19.5 and 23 microns from the Wyoming Infrared Observatory over the past six years has been examined. It is found that the transparency is largely controlled by the season. Four months: June, July, August, and September have very poor 20-micron transparency. During the rest of the year the transparency is usually quite good at 19.5 microns and moderately good at 23 microns. Using rawinsonde data and theoretical calculations for the expected infrared transparency, the measures of 20-micron transparency were calibrated in terms of atmospheric water-vapor content. The water vapor over the Wyoming Infrared Observatory is found to compare favorably with that above other proposed or developed sites: Mauna Kea, Mount Graham, and Wheeler Peak.

Grasdalen, G. L.↗

NASA NTRS1985

An observed upper limit on stratospheric hydrogen peroxide

Observations collected by a ground-based heterodyne receiver of an emission from the 7(0.7)-6(1.5) rotational torsional transition of H2O2 at 270.610 GHz are studied. An integrated spectrometer output of the data obtained at Mauna Kea, Hawaii in late May and early June of 1983 is presented. The removal of the ozone line background profile from the data is described. With no signal detected in the output of a 256-channel filter spectrometer the calculation of an upper limit on stratospheric H2O2 is possible. The utilization of the mixing ratio profile of Sze and Ko (1984) to compute the limit of H2O2 is examined. An upper limit for H2O2 of approximately 1 x 10 to the 14th/cu cm between 30-50 km is established.

De Zafra, R. L.↗

NASA NTRS1986

Research in planetary astronomy

The composition, structure and processes operating on the surfaces of solar system objects were determined using the Mauna Kea observing facilities and modern instrumentation. Reflectance spectroscopy and multispectral imaging in the 0.3 to 5.0 micrometers spectral region are the major techniques used. Major focus was in qualifying and using the new imaging spectrometer and the 2-D IR detectors for spectroscopy and imaging. The major observational program emphasis was on preparing for the next Mars opposition, and searching for compositional units in the lunar highlands.

Mccord, T. B.↗