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EIT Observations of the 15 November 1999 Mercury Transit
Auchère, F.; Artzner, G. E.
The Mercury transit of 15 November 1999 has been observed from space by the SOHO and TRACE spacecraft. We exploited the data recorded by EIT/SOHO to determine the stray-light level and the plate-scale of the instrument. The asymmetric distribution of stray light across the images is confirmed, but the absolute amount was found to be higher than pr…
The phase curve of cometary dust: Observations of comet 96P/Machholz 1 at large phase angle with the SOHO LASCO C3 coronagraph
Schwenn, R.; Jockers, K.; Grynko, Ye.
We have analyzed brightness and polarization data of comet 96P/Machholz, obtained with the SOHO-LASCO C3 coronagraph at phase angles up to 167° and 157°, respectively. The polarization data are characteristic of a typical dusty comet. Within error limits the corresponding trigonometric fit describes the new data measured at l…
Pulsational Evidence for Mass Loss in NGC 1866 Cepheids
Marconi, M.; Musella, I.; Caputo, F. +2 more
Available observational data for the 20 known Cepheids in the LMC cluster NGC 1866 have been compared with Hubble Space Telescope observations, discovering in the cluster central region five additional variables, one of which appears to be a Cepheid candidate. We also reach the conclusion that only the photometric data for the seven variables in t…
CDS wide slit time-series of EUV coronal bright points
Foley, C. R.; Doyle, J. G.; Nakariakov, V. M. +1 more
Wide slit (90''×240'') movies of four Extreme Ultraviolet coronal bright points (BPs) obtained with the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SoHO) have been inspected. The wavelet analysis of the He I 584.34 Å, O V 629.73 Å and Mg VII/IX 368 Å time-series confirms the oscillat…
The Needles in the Haystack Survey: searching for X-ray-selected normal galaxies
Georgantopoulos, I.; Plionis, M.; Georgakakis, A. E. +2 more
In this paper we present the first results from an ongoing serendipitous survey aiming to identify X-ray-selected `normal' galaxies [i.e. not dominated by active galactic nuclei (AGNs)] by combining archival XMM-Newton data with the Sloan Digital Sky Survey. In the first 4.5 deg2 of this program, we have identified a total of 11 `normal…
Abundances of Neutron-Capture Elements in the Hot Extreme Helium Stars V1920 Cygni and HD 124448
Rao, N. Kameswara; Lambert, David L.; Pandey, Gajendra +1 more
Analysis of Hubble Space Telescope Space Telescope Imaging Spectrograph ultraviolet spectra of two hot extreme helium (EHe) stars, V1920 Cyg and HD 124448, provides the first measurements of abundances of neutron-capture elements for EHe stars. Although the two stars have similar abundances for elements up through the iron group, they differ strik…
The XMM-Newton/2dF survey - III. Comparison between optical and X-ray cluster detection methods
Georgakakis, A.; Georgantopoulos, I.; Plionis, M. +4 more
We directly compare X-ray and optical techniques of cluster detection by combining Sloan Digital Sky Survey photometric data with a wide-field (~1.6 deg2) XMM-Newton survey near the North Galactic Pole region. The optical cluster detection procedure is based on merging two independent selection methods: a smoothing + percolation techniq…
GIRAFFE multiple integral field units at VLT: A unique tool to recover velocity fields of distant galaxies
Flores, H.; Hammer, F.; Puech, M. +2 more
The GIRAFFE spectrograph is unique in providing the integral field spectroscopy of fifteen distant galaxies at the same time. It has been successfully implemented at the second VLT unit within the FLAMES facility. We present GIRAFFE observations acquired during the Guaranteed Time Observation of the Paris Observatory, using total exposure times ra…
CLUSTER observations of lower hybrid waves excited at high altitudes by electromagnetic whistler mode signals from the HAARP facility
Pickett, J. S.; Inan, U. S.; Platino, M. +3 more
We report new observations from the CLUSTER spacecraft of strong excitation of lower hybrid (LH) waves by electromagnetic (EM) whistler mode waves at altitudes >=20,000 km outside the plasmasphere. Previous observations of this phenomenon occurred at altitudes <=7000 km. The excitation mechanism appears to be linear mode coupling in the pres…
Cluster observations in the magnetotail during sudden and quasiperiodic solar wind variations
Balogh, A.; Lucek, E.; Kim, K. -H. +5 more
A clear bipolar (negative/positive) signature in the Ey component was observed by three spacecraft on Cluster in the magnetotail during the passage of a solar wind discontinuity on October 11, 2001 (day 284), which caused a sudden commencement (sc) on the ground. The positive Ey perturbation was accompanied by the northward/d…