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The interplanetary magnetic field from 1 to 5 AU: Ulysses observations
Balogh, A.; Tsurutani, B. T.; Forsyth, R. J. +3 more
Observations of the Interplanetary Magnetic Field (IMF), carried out from October 1990 to February 1992, during the in-ecliptic phase of the Ulysses mission, are presented in this paper. The observations were made between 1 and 5.4 AU, during a different phase of the solar cycle from previous missions. The large scale reorganisation of the solar c…
Faint Object Camera Far-Ultraviolet Objective Prism Observations of 12 Z > 3 Quasars
Boksenberg, A.; Barbieri, C.; Weigelt, G. +16 more
We present the first results of an exploratory objective prism survey of the far-ultraviolet (λλ1200-1800) spectra of high-redshift quasars obtained with the Faint Object Camera on-board the Hubble Space Telescope. The prime objective of this survey is to identify one or more candidates among the known quasars at Ζem > 3 with suffici…
The spectral variability of the gamma-ray emission from Geminga and VELA and its implications.
Grenier, I. A.; Hermsen, W.; Henriksen, R. N.
The gamma-ray emissions from Geminga and from the Interpeak 1 component of the Vela pulsar were analyzed in order to compare their spectral properties between 50 MeV and 5 GeV and to study their variability between 1975 and 1982 using the COS-B data. The stability of both sources above about 200 and 300 MeV, respectively, retaining an E exp -2.0 +…
Near-Infrared and Ultraviolet Spectrophotometry of the Young Planetary Nebula Hubble 12
Feibelman, Walter A.; Erwin, Peter; Rudy, Richard J. +2 more
The young planetary nebula Hubble 12 is observed using near-IR and UV spectrophotometry. The brightness of the O I lines, which is greater than in any other planetary nebula yet measured, indicates that fluorescent excitation by stellar continuum is the principal mechanism generating these lines. Extinction, electron density, and electron temperat…
Ulysses observations of auroral hiss at high Jovian latitudes
Bame, S. J.; Kellogg, P. J.; MacDowall, R. J. +8 more
During the Ulysses flyby of Jupiter, a whistler-mode emission was periodically detected by the Unified Radio and Plasma wave (URAP) experiment during intervals when the spacecraft extended to high magnetic latitudes. The signal was detected between the local electron plasma frequency and lower hybrid resonance and appears as a funnel-shaped struct…
CCD astrometry and instrumental (Delta)V photometry of wide visual double stars. III. Differential measurements of often observed southern pairs.
Sinachopoulos, D.; van Dessel, E.
We present accurate relative positions and instrumental visual (Bessel V) magnitude differences of southern wide star components. The mean accuracy of the angular separation is 0.02 arcsecs, which corresponds to 1.5 micron on the CCD chip, and of magnitude difference 0.007 mag/exposure. The program pairs are targets of the HIPPARCOS mission and th…
Electron Density Diagnostics for Gaseous Nebulae Involving the O IV Intercombination Lines near 1400 Angstrom
Feibelman, W. A.; Keenan, F. P.; Conlon, E. S. +2 more
The Bloom and Pradhan (1992) results on the excitation rates for transitions in O IV matrix are used to derive emission-line ratios near 1400 A, applicable to gaseous nebulae. The results are compared with the values measured from high-resolution spectra obtained by the IUE satellite.
Variability and emission mechanism in Seyfert 1 galaxies : a near-infrared outburst in NGC 4051.
Hunt, L. K.; Del Zanna, G.; Wamsteker, W. +6 more
In the course of a 2.2 micron monitoring programme of nearby Seyfert 1 galaxies, we have detected an outburst in NGC 4051 in which the source flared and dimmed by more than a factor of 2 in 6 months. The UV flux, although sparsely sampled, is less variable than the near infrared. The available data suggest that dust reprocessing of the UV radiatio…
A New Look at the Dust Toward Omicron Persei and Sigma Scorpii With the International Ultraviolet Explorer
Clayton, Geoffrey C.; Hanson, Margaret M.
The first IUE low dispersion spectra for Omicron Persei and Sigma Scorpii have been obtained and extinction curves from 1150 to 3250 A are presented. It is of interest to consider Omicron Persei and Sigma Scorpii dust in the context of the average extinction law of Cardelli et al (1989), here referred to as 'CCM', which depends on the R(v) paramet…
Giotto's second encounter: The mission to comet P/Grigg-Skjellerup
Schwehm, G.; Grensemann, M. G.
The second highlight in the life of the Giotto spacecraft, which was originally designed for a short 8-month lifetime, occurred on 10 July 1992. The main mission was to explore and photograph Halley's Comet; however, not only did Giotto survive the harsh environment around the comet Halley but is was also able, after more than 7 years in orbit aro…