Search Publications
A comparison of the SAO-Hipparcos reference frames
Arias, E. F.; Cionco, R. G.; Orellana, R. B. +1 more
The reference systems defined by the SAO and Hipparcos catalogues are compared using vector spherical harmonic analysis. The differences between astrometric data in both catalogues have been grouped into different data sets and separate harmonic analysis performed on them. The Fourier coefficients yield estimates of systematic errors in SAO catalo…
Comparisons of Interplanetary Scintillation and Optical Measurements of Solar Wind Acceleration with Model Results
Thompson, B. J.; Breen, A. R.; de Forest, C. F. +4 more
Observations of the fast, high latitude solar wind show that acceleration of the fast wind is complete by 10 solar radii (R), while measurements from the LASCO instrument on SOHO show that most of the acceleration takes place inside 5 R. A series of observations were made in September 1997 using EISCAT and the C2 and C3 coronagraphs aboard SOHO to…
In-Flight Calibration of the ROSAT HRI Ultraviolet Sensitivity
Micela, G.; Murray, S. S.; Barbera, M. +2 more
Comparing measured and estimated count rates of a few selected sample stars, we confirm the validity and provide the in-flight calibration of the ROSAT HRI UV/visible effective area model in Zombeck et al. The count rate estimates for Betelgeuse derived with this model are in agreement with the measured HRI upper limit. This result is also confirm…
Bulk flow velocities in the solar corona
Simnett, G. M.; Lewis, D. J.
We present velocity estimates of bulk motions in the solar corona using data from the Large Angle Spectrometric Coronagraph (LASCO) aboard the Solar and Heliospheric Observatory spacecraft (SOHO). We describe a new technique which automatically provides a mass-weighted mean velocity profile in an entirely objective fashion without the need for ind…
Energetic Particle Signatures of a Corotating Interaction Region from a High Latitude Coronal Hole: SOHO, Wind and Ulysses Observations
Thompson, B. J.; Lazarus, A. J.; Kunow, H. +10 more
In mid 1996 the Comprehensive Suprathermal and Energetic Particle Analyser (COSTEP) onboard the Solar and Heliospheric Observatory, at 1 AU in the ecliptic plane, detected recurrent periods of enhanced MeV ions in association with a corotating interaction region (CIR). Measurements of energetic ions from the Cosmic Ray and Solar Particle Instrumen…
Cluster II: Plasma Measurements in Three Dimensions
Escoubet, C. P.; Schmidt, R.
After the dramatic accident of the first Ariane 5 rocket on 4 June 1996, causing the loss of the four European Space Agency's Cluster spacecraft, a recovery programme was initiated. During 10 months, alternative studies and intense negotiations were conducted with industry, and on 3 April 1997, the ESA Science Programme Committee agreed on the re-…
Absorption line systems on the line of sight from SN 1987A to SN 1993J and the intergalactic cloud in front of M 81
de Boer, K. S.; Marggraf, O.
We present an extended analysis of the high dispersion IUE spectra of
Signatures of Magnetic Reconnection and Observed EUV Emission Line Profiles in An Active Region
Wilhelm, K.; Kjeldseth-Moe, O.; Brekke, P. +2 more
We report on observations with SUMER on SOHO of high-velocity events, also called explosive events. The high spatial and spectral resolutions of SUMER allow simultaneous observations of EUV emission lines formed at different temperatures within the transition region. Complex line profiles with three separate line components appear to be a characte…
A survey of selected areas in the galactic plane with ISOCAM
Shipman, R. F.; Price, S. D.; Alard, C. +7 more
Seven 11.6' × 11.6' fields along the inner Galactic plane were imaged by the Infrared Space Observatory's ISOCAM camera to investigate the large scale properties of the Galaxy. We present results from this GPSURVEY program at wavelengths of 10 and 15 µm as well as some complementary observations from the ISOGAL project at 7 µm. Point s…
Uncertainty of total solar irradiance: an assessment of the last twenty years of space radiometry
Fröhlich, C.; Anklin, M.