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Simultaneous UV, optical and radio monitoring of the BL Lac object OJ 287 in March 1993

Maraschi, L.; Pian, E.; Quirrenbach, A. +26 more

The BL Lacertae object OJ 287 was intensively monitored with the IUE satellite from 1993 March 15 to 20 in the 2000-3000 Angstroms wavelength region. The very low emission state of the source hampered the detection during part of the 23 performed exposures. The light curve at 2650 Angstroms constructed with the 11 best images exhibits a variable t…

The induced magnetosphere of comet Halley 3. The plasma kinematics

Neubauer, F. M.; Israelevich, P. L.; Ershkovich, A. I.

The plasma velocity in the magnetosphere of comet Halley is calculated by using the displacement of magnetic field lines during the Giotto flyby. The obtained profile is in good agreement with that found from the momentum balance condition. The radial component of plasma velocity measured in situ (Schwenn et al., 1987) correlates well with the spa…

Far-UV emissions from the SL9 impacts with Jupiter

Talavera, A.; Feldman, P. D.; Strobel, D. F. +20 more

Observations with the International Ultraviolet Explorer (IUE) during the impacts of the fragments of comet D/Shoemaker-Levy 9 with Jupiter show far-UV emissions from the impact sites within a ∼10 min time scale. Positive detections of H₂ Lyman and Werner band (1230-1620 Å) and H-Lyα emissions are made for impacts K and S, and marginall…

Corotation of Jupiter's three-dimensional magnetosphere

Lanzerotti, L. J.; Maclennan, C. G.; Hawkins, S. E., III +1 more

An understanding of the corotational characteristics of planetary magnetospheres is essential for a complete description and comprehension of the plasma physics of these astrophysical objects. The corotational properties of Jupiter's magnetosphere have been revealed by data from the Voyager and Ulysses spacecraft. The near-equatorial hot plasma sh…

Modulation of galactic cosmic ray particles observed on board the ULYSSES spacecraft

Sierks, H.; Kunow, H.; Wibberenz, G. +9 more

The cosmic ray flux observed with the Kiel Electron Telescope on board the ULYSSES spaceprobe varies with solar activity as well as with heliospheric position. Determination of spatial gradients requires a careful analysis of the influences of the current sheet tilt angle, the number of major solar flares, interplanetary shocks and interaction reg…

The Faint Limit of the Hubble Space Telescope Faint Object Spectrograph and Rejection of the Cosmic-Ray Background

Tytler, David; Davis, Christopher

The faintest object which can be observed with the Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) is set by the detector cosmic-ray background and not by object flux. We use data from Beaver and Lyons to show that 48% of the background counts are from cosmic rays which each generate a near instantaneous burst of two or more counts. S…

Anisotropies of Interstellar Pickup Protons - Implications for Scattering of Low Rigidity (∼1 to 3 MV) Particles

Gloeckler, G.; Fisk, L. A.; Schwadron, N.

Interplanetary Type III Radio Bursts Observed Simultaneously by ULYSSES and ICE

Stone, R. G.; Reiner, M. J.; Hoang, S. +1 more

We analyze two solar type III radio bursts that were observed simultaneously by the ICE and Ulysses spacecraft. Both bursts originated behind the solar limb as viewed from either spacecraft. At the time of these events, ICE was in the ecliptic plane at ∼1 AU and Ulysses was ∼ 35° south of the ecliptic plane at ∼4 AU. For one event on 931117, the r…

VRI photometry of wide double stars with A- type primaries.

Cuypers, J.; Lampens, P.; Sinachopoulos, D. +2 more

We are presenting VRI photometry of 93 wide visual double stars having late B- or A- type primaries, taken from the Annex of Double and Multiple Stars of the HIPPARCOS Input Catalogue. Spectral types have been estimated for most of the primaries and for the majority of the secondaries. 40% of them probably have common origin components, for which …

The broad band energy distribution of the misaligned gamma-ray blazar PKS 0521-365

Maraschi, L.; Ghisellini, G.; Pian, E. +4 more

Simultaneous UV and X-ray observations of the blazar PKS 0521-365 are combined with radio, IR, optical and gamma-ray data taken at different epochs to study the overall emission from 10^9 to 10^23 Hz. The energy distribution declines from the IR to the UV range (alpha_opt-UV = 1.4 +/- 0.1), buthardens at higher frequencies. The remarkably flat X-r…