Search Publications
The radial velocity and binary of X Persei.
Stickland, D. J.
It is shown on the basis of radial velocity measurements on high-resolution spectra of X Persei from the IUE archive that there is no variation above the level of a few km/s and thus no need for a massive unseen component in the system. This does not rule out a neutron star or white dwarf orbiting in the variable wind of the Be star.
TYCHO Astrometry Calibration
Pedersen, H.; Lindegren, L.; Bastian, U. +6 more
The Hipparcos satellite's star mapper gives photon counts in two spectral channels simultaneously. The transit times and the signal amplitudes for each star across two groups of four slits are derived and used for astrometry and photometry, respectively, and this constitutes the Tycho project. The present paper describes the Tycho astrometric data…
First X-ray spectrum of the most luminous quasar PKS 2126-158.
Ghosh, K. K.; Soundararajaperumal, S.
For the first time the detailed results of the spectral analysis of the X-ray (0.1-10 keV) spectrum of the luminous (z = 3.27), radio-loud quasar, PKS 2126 - 158, are presented. The spectrum of this quasar was obtained from the EXOSAT database. Power law and fixed absorption model fits well with the spectrum. The parameters of this model suggest t…
The spectrum of the VV Cephei star KQ Puppis (Boss 1985). II. Atlas of the optical and ultraviolet spectrum.
Altamore, A.; Rossi, C.; Baratta, G. B. +1 more
An Atlas is presented of the high-resolution spectrum of the VV Cep M1-2Iab + Be variable KQ Pup (Boss 1985). The Atlas is based on UV observations obtained in 1979 with the IUE (covering the region from 1223 A to 3228 A) and on coude plates covering the blue to the optical UV. The equivalent widths and radial velocities of the main features prese…
The Spacelab-1 very wide field survey of UV-excess objects. III. Analysis of the IUE high-resolution spectra of two very hot sdO stars.
Deleuil, M.; Viton, M.
The IUE high resolution spectra of CPD-71 deg 172B had LSII+18 deg 9 (two subdwarfs with T(eff) = 60,000 K) are compared through a differential curve of growth technique. About 300 lines belonging to 15 ions have been identified in a series of selected windows, representing a global spectral domain of 50 A. Unknown lines account for 37 to 80 perce…
Ultraviolet Emission in the Dark Cloud Toward HD 62524
O'Donnell, James E.; Cardelli, Jason A.; Churchwell, Ed
We have obtained low resolution IUE short wavelength spectra at several positions within a ridge of molecular gas within the Gunn Nebula. Optical absorption line measurements toward HD 62542 indicate moderately high densities within the ridge. The physical appearance of the ridge, along with H-alpha and IRAS images of the nebula, suggest that wind…
High Resolution Imaging of QSO 2305+187 (=4C 18.68)
Hutchings, J. B.; Neff, S. G.; Crabtree, D. +1 more
We present optical imaging of QSO 2305+187 with resolution ranging from 0.1 to 1.0 arcsec, in continuum and line emission. The data are from FOCAM and the HR Cam of the Canada-France-Hawaii telescope, and the Wide Field Camera of the Hubble Space Telescope. These are compared with previously published optical and radio images. The QSO host galaxy …
Periodic errors of stellar abscissae in the HIPPARCOS experiment caused by oscillations of the basic angle
Makarov, V. V.
The problem of stellar abscissae error propagation originating from systematic variations of the basic angle during one turn of the Hipparcos satellite is investigated within the framework of a general data processing algorithm. These variations may be caused by systematic irregularities of the heat flux from solar radiation as the satellite's opt…
The effect of the shock of 15:43 UT March 23, 1991 on 50 keV to 5 MeV ions at Ulysses
Simnett, G. M.; Armstrong, T. P.; Roelof, E. C. +2 more
The intensities, angular distributions, and energy spectra of 50 keV to 5 MeV ions are examined in the several hour time interval when an interplanetary shock passed the Ulysses spacecraft. The increase in intensity, evolution of pitch angle distribution from upstream flow away from the shock to a post-shock “pancake” distribution, the earlier arr…
Method of comparison between determinations of the HIPPARCOS attitude
Donati, F.; Sechi, G.
An attitude comparison method for assessing the quality of the attitude estimates obtained by the Hipparcos data reduction consortia (FAST and NDAC) is presented. The method is illustrated by results obtained in a typical FAST-NDAC comparison developed during the attitude determination assessment phase. The aim of the attitude comparison is, initi…