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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 415 records · Page 23
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NASA NTRS1972

Ultraviolet photometry of planetary nebulae

Nine of the planetary nebulae observed by the Wisconsin filter photometers are compared with 15 Monocerotis in the spectral region 1430-4250 A. The data are corrected for the degradation of the filters of stellar photometer number four with time. Comparisons with simple models indicate that most of the observed nebulae are subject to some interstellar extinction in the far ultraviolet. However, NGC 246 and NGC 1360 appear to be nearly unreddened. Thus far no unexpected features have been found in the observations.

Holm, A. V.↗
NASA NTRS1972

Absolute calibration of ultraviolet filter photometry

The essential features of the calibration procedure can be divided into three parts. First, the shape of the bandpass of each photometer was determined by measuring the transmissions of the individual optical components and also by measuring the response of the photometer as a whole. Secondly, each photometer was placed in the essentially-collimated synchrotron radiation bundle maintained at a constant intensity level, and the output signal was determined from about 100 points on the objective. Finally, two or three points on the objective were illuminated by synchrotron radiation at several different intensity levels covering the dynamic range of the photometers. The output signals were placed on an absolute basis by the electron counting technique described earlier.

Bless, R. C.↗
NASA NTRS1972

Preliminary results of OAO ultraviolet photoelectric photometry of galaxies

General results are presented based on nearly completed reductions of data for approximately 35 galaxies of all Hubble types. In general the visual and ultraviolet energy distributions are well correlated. The energy distribution in late-type galaxies appears to turn up sharply in the region around 2000 A, and this is tentatively interpreted as due to the presence of early-type stars whose energy distribution is modified by interstellar dust within these objects. Similar turnups may be present in several elliptical galaxies but the evidence at this time is not definitive.

Code, A. D.↗
NASA NTRS1972

Ultraviolet photometry from the Orbiting Astronomical Observatory. II Interstellar extinction.

Evaluation of interstellar extinction curves over the region from 3600 to 1100 A for 17 stars. The observations were made by the two Wisconsin spectrometers on board the Orbiting Astronomical Observatory 2, with spectral resolutions of 10 and 20 A. The extinction curves generally show a pronounced maximum at 2175 plus or minus 25 A, a broad minimum in the region from 1800 to 1350 A, and finally a rapid rise to the far-ultraviolet. Large extinction variations from star to star are found, especially in the far-ultraviolet; however, with only two possible exceptions in this sample, the wavelength at the maximum of the extinction bump is essentially constant. These data are combined with visual and infrared observations to display the extinction behavior over a range in wavelength of about a factor of 20. The observations appear to require a multicomponent model of the interstellar dust.

Bless, R. C.↗
NASA NTRS1972

Photometry of compact galaxies.

Photometric histories of the N galaxies 3C 390.3 and PKS 0521-36. Four other compact galaxies, Markarian 9, I Zw 92, 2 Zw 136, and III Zw 77 showed no evidence of variability. The photometric histories were obtained from an exhaustive study of those plates of the Harvard collection taken with large aperture cameras. The images of all galaxies reported were indistinguishable from stars due to the camera f-ratios and low surface brightness of the outlying nebulosities of the galaxies. Standard techniques for the study of variable stars are therefore applicable.

Shen, B. S. P.↗
NASA NTRS1972

Ultraviolet photometry from the orbiting astronomical observatory. III - Observations of Venus, Mars, Jupiter, and Saturn longward of 2000 A.

A number of high-quality spectra of Mars, Jupiter, the combined disk and rings of Saturn, as well as lower-quality spectra of Venus, have been obtained with an objective-grating spectrometer of the Wisconsin Experiment Package of OAO-2. An intercomparison of the Mars, Jupiter, and Saturn spectra has failed to disclose any discrete planetary absorptions. Continuous albedos have been derived for the four planets by using OAO-2 observations of G-type stars for wavelengths greater than 2700 A. The geometric albedo of Mars shows a steady increase below 3500 A which appears to be due to Rayleigh scattering combined with a decreasing surface reflectivity. The albedos of Venus, Jupiter, and Saturn show a maximum in reflectivity in the region of 2500 A.-

Wallace, L.↗
NASA NTRS1972

Surface photometry of celestial sources from a space vehicle - Introduction and observational procedures.

Consideration of the possibility of studying diffuse celestial sources of relatively low surface brightness such as the Milky Way, zodiacal light, and gegenschein from above the earth's atmosphere with equipment flown in artificial satellites. The techniques used for this purpose are reviewed, and some of the difficulties encountered in daytime observations from satellites by the use of a special photometer and polarimeter flown in the orbiting skylab observatory, OSO-6, are cited.

Roach, F. E.↗
NASA NTRS1972

Mariner 6 and 7 ultraviolet spectrometer experiment - Photometry and topography of Mars.

From data obtained by the ultraviolet spectrometers aboard the Mariner 6 and 7 Mars missions the reflectivity of the illuminated disk of Mars was found to have two distinct spectral types, associated with polar and nonpolar regions. In this work the characteristic spectrum of nonpolar regions on Mars is discussed. An interpretation of the variation of the intensity at 3050 A due to surface pressure variations is given. A comparison of the ultraviolet observations with pressures inferred by the infrared spectrometer is used to test this interpretation and to determine physical parameters of Mars which lead to the observed reflectance. Earth based pressures obtained by broadening of the one-micron band of CO2 and radar topography are compared with the ultraviolet results.

Hord, C. W.↗
NASA NTRS1972

Tilting-filter measurements in dayglow rocket photometry.

A rocket-borne photometer containing two tilting-filter channels for the measurement of the forbidden OI 6300-A and 5577-A emission lines in the day airglow is described. The results of one flight substantiate the employment of tilting filters to determine accurate corrections for background continuum and provide reliable height profiles of emission intensity down to approximately 90 km. Discussions on the calibration of the instrument and its baffling against sunlight are also presented.

Schaeffer, R. C.↗
NASA NTRS1972

Photometry of comets

The photometric observations of comets are discussed in terms of providing profiles of the whole comet.

Miller, F.↗
NASA NTRS1972

L Alpha Photometry of Comet Bennett

Results of scanning Comet Bennett in L alpha from OGO-5 are reported. A plot of the comet isophotes in L alpha is presented. The outer envelope of the comet is approximately the 50-Rayleigh contour.

Dubin, M.↗
NASA NTRS1972

Narrow-band Photometry of the Galilean Satellites

Observations were made of the Galilean satellites in a narrow-band photometric system with a resolution of approximately 30 that covers the wavelength range from 0.3-1.1 microns. The absolute scale of the system is determined from stellar model computations. It is concluded that 35 Leo, the main comparison star used, has an energy distribution similar to the sun. An attempt is made to interpret the albedo curves in terms of surface constituents.

Wamsteker, W.↗
NASA NTRS1973

Photographic photometry of variable stars

Photographic methods of determining stellar magnitude and measuring brightness of variable stars on negatives include the photoelectric method and the contascope. Calibration curves are usually plotted by the UBV method. Magnitudes of comparison stars can be determined from photographs.

Kholopov, P. N.↗
NASA NTRS1973

UV photometry of eclipsing variables

UV photometric observations of the eclipsing variable CW Cephei by orbiting OAO-2 instrument package reveal the binary to be a system in an active stage of evolution, with evidence for stellar mass loss or mass exchange.

Sobieski, S.↗
NASA NTRS1972

Ultraviolet photometry of the moon with the celescope experiment on the OAO-II.

Thirteen television frames of the moon taken in the wavelength regions of 1350 to 2150 A by filter U3 and 1050 to 2150 A by filter U4 of the Smithsonian Astrophysical Observatory's Celescope experiment are discussed. The data include phase angles from -81 to -26 deg. The brightness dependence on phase angle differs slightly from that of visual observations. The brightness dependence on selenographical longitude is compared with the theoretical photometric function derived by Hapke.

Ahmad, I. A.↗