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Ultraviolet and Optical Observations of OB Associations in M31
O'Connell, R. W.; Bohlin, R. C.; Stecher, T. P. +7 more
Images of the central and southern parts of the local group Sb spiral galaxy M31 were obtained by the Ultraviolet Imaging Telescope during the Astro-1 Spacelab mission. Stellar photometry is obtained for 611 stars in 59 van den Bergh associations in the near-UV A1 band (central wavelength 2490 A), and for 130 of these stars in the far-UV B1 band (…
Properties of the +70 Kilometers per Second Cloud toward HD 203664
Sembach, Kenneth R.
I present high-resolution International Ultraviolet Explorer (IUE) spectra of the ultraviolet absorption in an intermediate-velocity interstellar cloud (nuLSR approximately equal to +70 km/s) toward HD 203664. The combined, multiple IUE images result in spectra with S/N = 15-40 and resolutions of approximately 20-25 km/s. The intermedia…
Anomalous cosmic ray oxygen and neon (∼2.4 MeV/nucl) at high southern heliolatitudes
Lanzerotti, L. J.; Maclennan, C. G.
We report measurements of the anomalous oxygen and neon as measured with the HI-SCALE instrument on Ulysses at high southern heliolatitudes. Using both energy spectral features and C/O ratios, 2.0-2.8 MeV/nucl anomalous O is not distinguishable below a latitude of ∼40°S. The heliolatitude gradient is found to be +0.06±0.50% / degree for the heliol…
X-ray observations of NGC 1851 and the globular cluster LMXBs
Charles, P. A.; Callanan, P. J.; Penny, A. J.
We present new Ginga observations of the globular cluster X-ray source 4U 0513-40 in NGC 1851. Despite the 2-d time-base of the observations, no eclipsing or dipping modulation was found. The spectrum can be well modelled by a power law of index 2.1 to energies of at least 10 keV. We find from archive EXOSAT data that an additional blackbody contr…
Medium-Resolution Far-Ultraviolet Spectroscopy of PKS 2155-304
Grewing, M.; Hurwitz, M.; Bowyer, S. +5 more
Using the Berkeley spectrometer of the Orbiting Retrievable Far and Extreme Ultraviolet Spectrometer (ORFEUS) we observed the 87-117 nm UV spectrum of the BL Lac object PKS 2155 - 304 with about 0.5 A resolution. In addition to the expected interstellar lines we detected higher quantum number counterparts of the intergalactic Lyα lines discovered …
The High Latitude Heliospheric Magnetic Field
Forsyth, R. J.
As the Ulysses spacecraft approaches its first pass under the south pole of the sun, it is an appropriate time to review our current knowledge and predictions regarding the three dimensional behaviour of the heliospheric magnetic field, in particular at high heliographic latitudes. Optical techniques for measuring the photospheric magnetic field a…
Astrometry of 19 globular clusters.
Johnston, H. M.; Picard, A.
We present accurate positions for the center of 19 globular clusters, 8 of which are known to contain X-ray sources and/or pulsars. The positions are based on a new centroiding algorithm applied to CCD images of the clusters. The fundamental astrometry is performed with plates from the ESO Schmidt telescope, using the Hipparcos Input Catalogue as …
Non-standard Extinction by Circumnuclear Dust in Active Galactic Nuclei
Szczerba, R.; Madejski, G.; Czerny, B. +2 more
Observational data imply that Active Galactic Nuclei are likely to have a substantial amount of dust within some 0.1-100pc. This dust modifies the observed spectrum of the nucleus by reprocessing a significant fraction of its intrinsic bolometric luminosity. The details of the emerging spectrum in the infrared and in the ultraviolet are dependent …
Dust particles beyond the asteroid belt - a study based on recent results of the Ulysses dust experiment
Mann, Ingrid; Grün, Eberhard
Dust fluxes detected by the Ulysses dust experiment beyond the asteroid belt, their possible sources and the possibilities of comparing them to observations of dust in the Zodiacal light are discussed. The dust fluxes detected at solar distances about r < 2.5 AU are compatible with a population of interplanetary dust particles moving on low ecc…
Properties of the HIPPARCOS Input Catalogue
Evans, D. W.; Arenou, F.; Lindegren, L. +17 more
The positions, proper motions, magnitudes and colour indices contained in the Hipparcos Input Catalogue are compared with preliminary Hipparcos mission results. The Hipparcos data considered, the `combined 30-month solution', or H30, is a preliminary catalogue derived from the analysis of the first 30 months of data (out of a total of 37 months), …