Ultraviolet Photometry Research Articles

Analysis of the IUE satellite and the ground-based observations of SW Lacertae

view Abstract Citations (7) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Analysis of the IUE Satellite and the Ground-based Observations of SW Lacertae Jeong, Jang Hae ; Kang, Yong Woon ; Lee, Woo Baik ; Sung, Eon Chang Abstract We present UBV observations of SW Lacertae obtained in 1988. We classify all previous light curves into three groups according to their maxima. The International Ultraviolet Explorer (IUE) spectra of SW Lacertae are used for ultraviolet photometry and for a variation study of chromspheric activity. Five light curves between the wavelengths of 2600 A and 3100 A are made from the low-dispersion IUE spectra. We have analyzed the UBV light curves and five IUE light curves independently by the modified differential correction method of Wilson and Devinney. Evidence of chromospheric activity is indicated by the intensity variation of the Mg II emission line with orbital phase. Publication: The Astrophysical Journal Pub Date: February 1994 DOI: 10.1086/173690 Bibcode: 1994ApJ...421..779J Keywords: Chromosphere; Eclipsing Binary Stars; Stellar Spectra; Ultraviolet Astronomy; Ultraviolet Spectra; Astronomical Spectroscopy; Atomic Spectra; Data Reduction; Emission Spectra; Iue; Light Curve; Line Spectra; Magnesium; Spaceborne Astronomy; Astrophysics; STARS: BINARIES: ECLIPSING; STARS: INDIVIDUAL CONSTELLATION NAME: SW LACERTAE; ULTRAVIOLET: STARS full text sources ADS | data products SIMBAD (3) MAST (1) INES (1)

High-Speed Hubble Space Telescope Ultraviolet photometry of two DB white dwarfs: Nonradial and radial pulsations

We observed two DB white dwarf stars with the High Speed Photometer aboard the Hubble Space Telescope. The two targets, the nonradial pulsator GD 358, and PG 0112+104, a non-pulsating white dwarf with similar temperature, were each observed for 1800 s with a time resolution of 10 ms. We used the F140LP configuration, which gives a broadband response in the UV between 1400 and 3000 A. The data clearly show the long period (about 700 s) pulsations in GD 358. Comparison with optical observations obtained two weeks earlier shows that the amplitude of the pulsations in the UV is approximately 1.4 times higher, consistent with nonradial pulsations due solely to temperature changes at constant radius. The high time resolution of these observations allows us to search for high-frequency pulsations (such as p modes or high overtone radial modes). No firm evidencefor high-frequency pulsations was seen in either object between 1 and 12 Hz. Correlation analysis of GD 358 shows no clear signal of multifrequency high overtone radial pulsations at the 0.00075 mag level, with no individual modes above the 0.0016 mag level. Upper limits for PG 0112+104 are approximately 2 times higher than for GD 358. Implications of this study for the theory of white dwarf pulsations are discussed.

Ultraviolet photometry of OB associations in M31

The study obtains near-UV and FUV magnitudes for 76 massive stars in 24 OB associations in the central and southern portions of M31 from images obtained by the Ultraviolet Imaging Telescope (UIT) during the Astro 1 spacelab mission. A comparison is made with the previous UIT photometry of 30 stars in the giant association NGC 206. Extinctions are estimated from the relation between E(B - V) and the distance from the center of M31 derived by Hodge and Lee (1988) from topical CCD stellar photometry. From evolutionary models, lower limits to the maximum stellar mass are estimated at about 60-100 solar masses in NGC 206, A29, A61, A63, A130, and A132. For other associations, the limits are in the range of about 20-55 solar masses.

High-speed ultraviolet photometry of HD 60435

We present the first high-speed ultraviolet photometry of an oscillating Ap star, HD 60435. After removing known orbital effects related to the Hubble Space Telescope, we confirm the presence of a strong pulsation period at a frequency of 123.70 cycles per day. In addition, we find significant amplitude modulation of this frequency that we suggest could be the result of beating of multiple periodicities. In this context, we suggest evidence for the presence of four additional frequencies at nu = 120.56, 126.55, 149.49, and 221.03 cycles per day. Three of these frequencies correspond well to frequencies detected in optical observations of HD 60435. The fourth, at 149.49 cycles per day, if real, is a potentially new pulsation mode that has not been detected in ground-based observations of this star. The amplitude of the 123 cycles per day pulsation is significantly larger in the ultraviolet than it is in the blue.

Extended near-ultraviolet continuum emission and the nature of the polarized broad-line Seyfert 2 galaxies

view Abstract Citations (87) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Extended Near-Ultraviolet Continuum Emission and the Nature of the Polarized Broad-Line Seyfert 2 Galaxies Pogge, Richard W. ; De Robertis, M. M. Abstract Narrow-band emission-line and continuum imaging in subarcsecond seeing conditions are presented for three Seyfert 2 galaxies: NGC 1068, Mrk 3, and Mrk 573. These images reveal, in addition to a wealth of emission- line structure, an extended, diffuse excess near-UV (3600 A) continuum component that has a conical or biconical morphology aligned with the radio axes of these galaxies. The nature of the diffuse excess near-UV continuum emission, which we interpret as scattered nuclear continuum light, and its implications for current models of Seyfert nuclei are discussed. Publication: The Astrophysical Journal Pub Date: February 1993 DOI: 10.1086/172308 Bibcode: 1993ApJ...404..563P Keywords: Active Galactic Nuclei; Galactic Radiation; Near Ultraviolet Radiation; Seyfert Galaxies; Ultraviolet Emission; Emission Spectra; Ultraviolet Photometry; Astrophysics; GALAXIES: NUCLEI; GALAXIES: SEYFERT; ULTRAVIOLET: GALAXIES full text sources ADS | data products SIMBAD (3) NED (3)

Field tests of a passive sampler for atmospheric ozone at California mountain forest locations

Field tests of a colorant-based ozone passive sampler have been carried out during the 1990 smog season at five mountain forest locations in California. Co-located measurements of ambient ozone were made at all field sites using the passive sampler and a reference method, ultraviolet (u.v.) photometry. The sampling duration ranged from 3 to 30 days. Nitrogen dioxide, aldehydes and the phytotoxic oxidants peroxyacetyl nitrate (PAN) and peroxypropionyl nitrate (PPN) were measured at one location to assess possible interferences. The average precision of the measurements, calculated from data for 42 sets of colocated passive samplers, was 12%. Data for all field locations could be reduced to a single equation relating color change ( ΔE units) to ozone dose (units: ppb-days). This polynomial equation could be reduced to a linear equation for color changes not exceeding 8 ΔE units (equivalent to sampling durations of up to 15 days), with good agreement between field data and earlier calibration results obtained in the laboratory. Both polynomial and linear equations can be used to obtain quantitative, time-integrated measurements of ambient ozone. The performance of the passive sampler showed no dependence on changes in ambient temperature and humidity. Interferences from air pollutants other than ozone contributed a total positive bias of less than 5% to the measured ozone concentrations: 3% for NO 2, 1.3% for PAN, 0.2% for PPN, and 0.% or less for formaldehyde and acetaldehyde.

CCD surface photometry of galaxies with dynamical data. II - UBR photometry of 39 elliptical galaxies

view Abstract Citations (520) References (71) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS CCD Surface Photometry of Galaxies with Dynamical Data. II. UBR Photometry of 39 Elliptical Galaxies Peletier, Reynier F. ; Davies, Roger L. ; Illingworth, Garth D. ; Davis, Lindsey E. ; Cawson, Michael Abstract We have obtained U, B, and R CCD surface photometry for a sample of 39 elliptical galaxies. For each galaxy we have determined the surface brightness profile, U - R and B - R color profiles, and the ellipticity and position angle profiles, all as a function of major axis radius, using a two-dimensional ellipse fitting program. In addition, we have derived the sin and cos 3 θ and 4 θ terms that describe the high-order deviations of the B and R isophotes from ellipses. While it is very common for ellipticals to display measurable 3 θ and 4 θ terms, the amplitudes of these terms rarely exceed 0.5%. The isophotes of elliptical galaxies are very well characterized by ellipses. The surface brightness and color profiles are given to radii at which the error in the profile reaches 0.1 mag from the uncertainty in the brightness of the night sky. We have carried out a series of simulations of the effects of seeing on luminosity and ellipticity profiles, to determine the radius beyond which the errors in our data from seeing are less than 0.05 mag and 0.02 in ellipticity. Measurable effects of seeing extend to surprisingly large radii, as much as 5 -10 seeing radii, depending upon the ellipticity of the galaxy and the form of the surface brightness profile. Ellipticity and position angle profiles are usually the same in all passbands with no indication that the contours of constant color are more or less flattened than the isophotes, i.e., the isochromes and isophotes have the same shapes, but the insensitivity of the ellipticity to differences between these properties makes this a weak argument. The high-order terms, particularly the 3θ terms, appear to be sensitive diagnostics for the existence of dust in ellipticals. We find that all the galaxies in this sample either become bluer in B - R and U - R with increasing radius or are of constant color. Mean values for the logarithmic gradients in color are -0.09 mag (arcsec)^-2^ per dex in radius in B - R, and - 0.20 mag (arcsec)^-2^ per dex in radius in U - R. These color changes are consistent with a decrease in the [Fe/H] of approximately 0.20 per decade in radius. Surprisingly, there is no correlation of color gradient with luminosity. It is striking, however, that the lowest luminosity galaxies in the sample (i.e., those with M_B_ > - 20) do not show any color gradients. They have boxy isophotes, and are also rotationally flattened. While these properties may be related to the fact that they are companions of larger ellipsoidal systems, it could provide an important clue to the formation of ellipticals. Low luminosity ellipticals that are not close companions to giant ellipticals need to be studied. Publication: The Astronomical Journal Pub Date: October 1990 DOI: 10.1086/115582 Bibcode: 1990AJ....100.1091P Keywords: Astronomical Photometry; Brightness Distribution; Elliptical Galaxies; Galactic Evolution; Galactic Structure; Ultraviolet Photometry; Charge Coupled Devices; Color-Color Diagram; Seeing (Astronomy); Astronomy; GALAXIES: PHOTOMETRY; GALAXIES: SURFACE full text sources ADS | data products SIMBAD (42) NED (40) CDS (1) Related Materials (1) Part 1: 1985AJ.....90..169D

An atlas of Hubble Space Telescope photometric, spectrophotometric, and polarimetric calibration objects

view Abstract Citations (258) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An Atlas of Hubble Space Telescope Photometric, Spectrophotometric, and Polarimetric Calibration Objects Turnshek, D. A. ; Bohlin, R. C. ; Williamson, R. L., II ; Lupie, O. L. ; Koornneef, J. ; Morgan, D. H. Abstract The information concerning the variation of sound speed and density inside the Sun as inferred from helioseismic inversion is employed to constrain the temperature and composition profiles in the solar core. The usual thermal transport and energy generation equations governing stellar structure are adopted to demonstrate that in order to reduce the chlorine neutrino flux to match the observed values, the opacity needs to be reduced by a factor upwards of 1.5. Further, assuming that the uncertainties in the tabulated OPAL opacity values are no larger than 20% in the core, the central temperature is bounded by 15.2 x 106 Tc 16.1 x 106 K. In order to get a temperature profile which is consistent with the observed solar luminosity and the helioseismic data, it appears that the nuclear energy generation rates will need to be revised upward by a few percent, although the estimate of the central temperature is not particularly affected by these uncertainties. With the current OPAL opacities, the central temperature is found to be (15.6 + 0.40) x 106 K. Publication: The Astronomical Journal Pub Date: April 1990 DOI: 10.1086/115413 Bibcode: 1990AJ.....99.1243T Keywords: Astronomical Photometry; Hubble Space Telescope; Polarimetry; Stellar Spectrophotometry; Calibrating; Charge Coupled Devices; Error Analysis; Ultraviolet Photometry; Astronomy; PHOTOMETRY; SPECTROPHOTOMETRY; POLARIZATION full text sources ADS | data products SIMBAD (147) MAST (1)

Dust clouds within globular clusters - Polarization

view Abstract Citations (12) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Dust Clouds within Globular Clusters: Polarization Forte, Juan C. ; Mendez, Mariano Abstract Multicolor polarization and CCD photometry are presented for four dust cloud candidates in the globular clusters NCG 362, 6266, 7078, and 7099. The results are in agreement with previous arguments, suggesting the physical membership of the clouds in the clusters. Tangential polarization is present in the last three objects. The observed polarization, after correction for dilution effects, is consistent with a 'gray' behavior and P about 2-3 percent. Alternatively, the dark patch in NGC 362 shows a polarization similar to that of the cluster nucleus, probably with an interstellar origin. The detection of scattered polarized light at angular distances close to four core radii shows that the dust complexes may be considerably extended. Publication: The Astrophysical Journal Pub Date: October 1989 DOI: 10.1086/167898 Bibcode: 1989ApJ...345..222F Keywords: Cosmic Dust; Globular Clusters; Molecular Clouds; Polarized Radiation; Charge Coupled Devices; Light Scattering; Polarimetry; Stellar Winds; Ultraviolet Photometry; Astrophysics; CLUSTERS: GLOBULAR; INTERSTELLAR: GRAINS; POLARIZATION full text sources ADS | data products SIMBAD (4)

Multicolor UBVRI observations of S289, S300, and S309

view Abstract Citations (2) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Multicolor UBVRI Observations of S289, S300, and S309 Lahulla, J. F. Abstract UBVRI photometry for three distant optical H II regions in the Galactic anticenter has been carried out at the 1.5 m telescope at Calar Alto (Spain). From these data, the distances and the absorptions are derived. The UBVRI photometry confirms that the extinction law is normal toward the stars in these H II regions. Publication: The Astronomical Journal Pub Date: June 1989 DOI: 10.1086/115112 Bibcode: 1989AJ.....97.1727L Keywords: Astronomical Photometry; H Ii Regions; Infrared Photometry; Ubv Spectra; Visual Photometry; Stellar Luminosity; Stellar Magnitude; Ultraviolet Photometry; Astrophysics; NEBULAE: H II REGIONS full text sources ADS | data products SIMBAD (6)

Spectroscopic Studies and Atmospheric Parameters of ZZ Ceti Stars

The pulsating ZZ Ceti stars cover a narrow range of effective temperatures along the cooling sequence of DA white dwarfs (see, eg., Winget and Fontaine 1982). Fast-photometric searches for pulsating stars in that class have provided strong evidence that the ZZ Ceti phase is an evolutionary phase through which all cooling DA stars will eventually go through (Fontaine et al. 1982). Recent investigations, based on optical or ultraviolet photometry and spectrophotometry, have set the boundaries of the instability strip at temperatures near 10,000-11,000 K and 12,000-13,000 K, respectively (McGraw 1979; Greenstein 1982; Weidemann and Koester 1984; Fontaine et al. 1985; Wesemael, Lamontagne, and Fontaine 1986; Lamontagne, Wesemael, and Fontaine 1987, 1988).

Determination of sulfur contents of vegetable and marine oils by ion chromatography and indirect ultraviolet photometry of their combustion products

AbstractA simple method for the determination of total sulfur content in vegetable and marine oils is described. The method involves combustion of the oil sample in an oxygen bomb to convert all forms of sulfur to sulfate ions with subsequent determination of the sulfate by ion chromatography and indirect ultraviolet detection. The ultraviolet system described is more sensitive than conductivity detection and enables the method to be applied more widely.Application of the method to a variety of vegetable and marine oils showed the general occurrence of sulfur in fats and oils, albeit often at a low level. Among the samples examined, crude Canola oil had the highest sulfur content (25.0 mg/kg) followed by the marine oils (5.8‐15.2 mg/kg) and the non‐Cruciferae vegetable oils (2.0‐6.1 mg/kg).

Accretion disks around T Tauri stars

view Abstract Citations (579) References (68) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Accretion Disks around T Tauri Stars Bertout, Claude ; Basri, Gibor ; Bouvier, Jerome Abstract The authors examine the proposition that many T Tauri stars are still actively accreting material from a surrounding disk of material formed at the same time as the star. It is shown that the observations are both unified and explained if classical T Tauri stars are chromospherically active pre-main-sequence stars with accretion disks. Contemporaneous optical and ultraviolet observations, along with extensive photometric monitoring in the optical and infrared, are used to test disk models and to show that there is evidence for accretion in the range 5×10-8 - 5×10-7M_sun;yr-1 from stars exhibiting strong ultraviolet excesses. These models also explain the infrared spectrum shortward of 10 μm and the total system luminosities. Publication: The Astrophysical Journal Pub Date: July 1988 DOI: 10.1086/166476 Bibcode: 1988ApJ...330..350B Keywords: Accretion Disks; Pre-Main Sequence Stars; Spectral Energy Distribution; Stellar Radiation; Stellar Spectrophotometry; T Tauri Stars; Balmer Series; Boundary Layers; Chromosphere; Infrared Photometry; Interstellar Extinction; Reynolds Number; Turbulent Flow; Ultraviolet Photometry; Ultraviolet Radiation; Viscous Flow; Astrophysics; STARS: PRE--MAIN-SEQUENCE; STARS: ACCRETION; SPECTROPHOTOMETRY full text sources ADS | data products SIMBAD (15) MAST (1) Related Materials (3) Part 2: 1989ApJ...341..340B Part 3: 1992A&A...263..113B Part 4: 1993A&A...275..236B

Specific Interactions of Dinucleoside Monophosphates with their Cognate Amino Acids

Specific interactions of anticodonic dinucleoside monophosphates and their cognate amino acids have been detected by using a precise ultraviolet difference asbsorbance photometry. The affinity coefficients are of the order of 1 M -1 , similar to those in the base-base stacking interactions, suggesting the lock and key relationship for the above interaction. All signals are hyperchromic and may be caused by destacking of the dinucleoside monophosphate due to the above complex formation.

Response of chemiluminescence NOx analyzers and ultraviolet ozone analyzers to organic air pollutants

A chemiluminescent NO/sub x/ analyzer and an ultraviolet photometry ozone analyzer were found to respond to a number of organic pollutants and mixtures in purified air. Two types of interferences were observed with the NO/sub x/ analyzer. A small positive interference as NO was observed with organosulfur compounds. Positive interferences as NO/sub 2/ were observed with nitric acid, methyl nitrate, peroxyacetyl nitrate, N/sub 2/O/sub 5/ (in O/sub 3/-NO/sub 2/ mixtures in the dark), certain nitro aromatics (nitrocresol), and chlorine-containing compounds (ClNO/sub x/) but not with peroxybenzoyl nitrate. The ultraviolet photometry ozone analyzer gave a positive response to ozone-free atmospheres containing aromatic compounds including styrene, methylstyrene, o-cresol, and nitrocresol. Since many aromatic compounds absorb light at approx. 254 nm, methods other than UV photometry should be employed to measure ozone in atmospheres containing these aromatics.

The ultraviolet variability of early-type supergiants

Four early-type supergiants - HD 79186 (B5 Ia), HD 96919 (B9 Ia), HD 105056 (ON9.7 Iae), and HD 148379 (B2 Iae) - have been observed with the low-resolution spectrographs of IUE in the large aperture on 14 days. The behavior of the ultraviolet fluxes with time is studied. The light from all four stars seems to vary. Typically the dispersion about the mean magnitude at any wavelength corresponds to + or - 0.085, + or - 0.080, + or - 0.101, and + or - 0.106 mag, respectively. These amplitudes exceed the typical uncertainty in an IUE measurement of flux by about a factor of 3; they are somewhat larger than the variations known in the visible wavelength range. There are insufficient data to investigate periodicity in the observed light changes. The effective temperatures and angular diameters of the stars have been estimated using the present ultraviolet photometry, published UBV and uvby photometry, and the model-atmosphere fluxes reported by Kurucz in 1979. The program stars have dimensions typical for their spectral types. A brief discussion is given of possible causes of the variability of hot supergiants.

Ultraviolet photometry from the Orbiting Astronomical Observatory. XXXIX - The structure of the eclipsing Wolf-Rayet binary V444 Cygni as derived from light curves between 2460 A and 3. 5 microns

The WN5 component of V444 Cyg is characterized on the basis of light curves constructed using 1971 OAO observations at 425, 332, 298, and 246 nm and the broadband data at 2.2 and 3.5 microns of Hartmann (1978). Data and calculation results are presented in tables and graphs and discussed. Parameters estimated include core radius 2.9 solar radii, surface temperature 90,000 K, surface electron density 9 x 10 to the 12th/cu cm, surface outflow velocity 400 km/s, and terminal velocity (at about 10 solar radii) 2500 km/s, suggesting that the flow is He. These results are found to agree with the model of Wolf-Rayet atmospheres proposed by Beals (1929, 1944).

Absolute photometry of the southern Orion region in the vacuum ultraviolet (1300-2000 A)

view Abstract Citations (7) References (32) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Absolute photometry of the southern Orion region in the vacuum ultraviolet (1300-2000 A). Tanaka, T. ; Onaka, T. ; Sawamura, M. ; Watanabe, T. ; Kodaira, K. ; Nishi, K. Abstract Absolute photometry of the southern Orion region was carried out for five passbands in the vacuum ultraviolet (1300-2000 A, Delta Lambda = 84 A) with a rocket-borne spectrometer. More than 60 early-type stars and the diffuse background radiation were observed within the raster-scanned field of 8 x 8 deg centered at alpha = 5 h 30 m and delta = -4 deg. Stellar data suggest a revision of the current absolute scale by 10-30 percent, which relatively suppresses the flux toward shorter wavelengths. The present data of the background radiation have the highest spectral resolution among those published and indicate a steep systematic increase of the flux toward shorter wavelengths. Direct consequences of the new calibration are briefly discussed. Publication: The Astrophysical Journal Pub Date: May 1984 DOI: 10.1086/161987 Bibcode: 1984ApJ...280..213T Keywords: Early Stars; Far Ultraviolet Radiation; Orion Constellation; Stellar Spectrophotometry; Ultraviolet Photometry; Background Radiation; Calibrating; Iue; Radiation Distribution; Rocket-Borne Instruments; Stellar Radiation; Astronomy full text sources ADS | data products SIMBAD (64)

The bright end of the color-magnitude relation for early-type galaxies in clusters

view Abstract Citations (29) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The bright end of the color-magnitude relation for early-type galaxies in clusters. Lugger, P. M. Abstract UBVR photoelectric photometry is presented for bright early-type galaxies in clusters. The sample is comprised of 26 first ranked cluster members, 14 fainter cluster members, and two field galaxies. The colors of first ranked galaxies in clusters appear to be independent of cluster morphology. A color difference as large as 0.1 mag in U-B between cD and normal first ranked cluster galaxies can be ruled out on the basis of the present data at the 5 σ level. Publication: The Astrophysical Journal Pub Date: March 1984 DOI: 10.1086/161767 Bibcode: 1984ApJ...278...51L Keywords: Astronomical Photometry; Galactic Clusters; Galactic Evolution; Ubv Spectra; Color; Histograms; Ultraviolet Photometry; Visual Photometry; Astronomy full text sources ADS | data products SIMBAD (99) NED (63)

Images in the rocket ultraviolet - Photometry of M101

view Abstract Citations (26) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Images in the rocket ultraviolet : photometry of M 101. Hill, J. K. ; Bohlin, R. C. ; Stecher, T. P. Abstract Three ultraviolet images of the Sc I galaxy M101 (NGC 5457) were obtained by a rocket-borne telescope, using a microchannel plate image intensifier coupled to IIa-O film, giving an effective wavelength of 2250 Å, a bandpass of 970 Å, and about 10arcsec resolution over an 80arcmin field. Extreme Population I dominates in the UV in the form of OB/H II complexes. The 57 OB/H II sources measured here account for half the UV flux of the galaxy. Large-scale spiral structure was investigated using azimuthal and radial profiles. A comparison with optical results shows that the colors of the disk and spiral arm components do not vary significantly with radius, and that the arm-to-disk ratio is a factor ≡3 higher in the UV than in the visible. Publication: The Astrophysical Journal Pub Date: February 1984 DOI: 10.1086/161724 Bibcode: 1984ApJ...277..542H Keywords: Image Intensifiers; Rocket-Borne Instruments; Spiral Galaxies; Ultraviolet Astronomy; Ultraviolet Photometry; Astronomical Photography; Bandpass Filters; Hydrogen Clouds; Nebulae; Stellar Evolution; Astronomy full text sources ADS | data products SIMBAD (182) NED (3)