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X-ray map from the EXOSAT galactic plane survey and a direct demodulation technique.
Lu, F. J.; Li, T. P.; Page, C. G. +2 more
In 1984 the EXOSAT observatory scanned the galactic plane with its medium-energy array which had a spatial resolution of about 0.75deg. The data analysis used at that time was unable to resolve some of the more complex regions near the galactic centre. The direct demodulation method is a technique to solve the image reconstruction problem in high …
UvbyHbeta_ photometry of main sequence A type stars.
Jordi, C.; Figueras, F.; Torra, J. +1 more
We present Stroemgren uvby and Hbeta_ photometry for a set of 575 northern main sequence A type stars, most of them belonging to the Hipparcos Input Catalogue, with V from 5mag to 10mag and with known radial velocities. These observations enlarge the catalogue we began to compile some years ago to more than 1500 stars. Our catalogue inc…
Ultraviolet properties of early-type galaxies.
Alloin, D.; Pastoriza, M. G.; Bonatto, C. +1 more
We analyse the UV properties of early-type galaxies from their UV spectra in the IUE library, including both normal and active nuclei. We co-added the spectra, and hence the objects into groups of similar spectral properties in the UV, also taking into account their properties in the visible/near-infrared ranges. Although, owing to the presence of…
Source standards for the radiometric calibration of astronomical telescopes in the VUV spectral range.
Huber, M. C. E.; Hollandt, J.; Kuehne, M. +1 more
On the basis of a high-current hollow-cathode discharge we have developed two transfer source standards suitable for the radiometric calibration of vacuum ultraviolet (VUV) telescopes. The source standards are transportable and (in their current design) produce a collimated beam of 5 and 10mm diameter. By irradiating the entrance aperture of the t…
First Cycle 4 multiwavelength observations of the gamma-ray quasar PKS 0208-512.
Vestrand, W. T.; Sreekumar, P.; Kubo, H. +3 more
We present first results of CGRO Cycle 4 multiwavelength observations of the gamma-ray quasar PKS 0208-512. A bright, variable gamma-ray source, PKS 0208-512 has been detected numerous times by the EGRET experiment aboard the CGRO, possessing one of the hardest spectra observed to date. The recent COMPTEL observations of Blom et al. (1995A&A..…
Probable detection of high-energy gamma-ray emission from OJ 287 during a major optical flare.
Shrader, C. R.; Hartman, R. C.; Webb, J. R.
We observed the BL Lac object OJ 287 with the CGRO/EGRET instrument as a target of opportunity triggered by an outburst in its visual intensity. OJ 287 is well known as a high-amplitude variable in the optical and radio domain, and recurrent outburst behavior at nominal 11.6-year intervals have led to speculation that there may be some determinist…
Mesures et decouvertes d'etoiles doubles effectuees a la lunette de 50cm de l'Observatoire de Nice. Measures and discoveries of visual double stars made with the 50cm refractor at the Nice Observatory.
Thorel, J. -C.
Measures and discoveries of visual double stars made at the Observatoire de la Cote d'Azur at Nice, between 1988 and 1994, with the 50cm refractor equipped with a filar micrometer and electronic recording device. The programs proposed by J. Dommanget involve the complement of the C.C.D.M. (resolving problems of identification of double stars and o…
Global astrometry with OSI.
Malbet, F.; Loiseau, S.
The Orbiting Stellar Interferometer is a proposed space-based interferometer which makes very accurate wide-angle astrometric measurements on several thousand stars. As opposed to Hipparcos, OSI does not have a "basic angle" between two separate field-of-views but three separate interferometers and a highly accurate metrology system. The questions…
Optical positions of radio emitting stars.
Assafin, M.; Andrei, A. H.; Puliaev, S. P. +4 more
In order to contribute to the alignment of the radio and optical reference frames, 50 stars with confirmed radio emission and published radio positions were observed by astrographical means. Additionally, two confirmed radio-stars of fainter magnitude were observed using a CCD direct camera with a long focus, large aperture telescope. The reductio…
Stars of the southern hemisphere proposed for the HIPPARCOS mission.
Rousseau, J. M.; Perie, J. P.; Gachard, M. T.
As part of the preparation for the Hipparcos mission, we determined the positions of 96800 already listed stars and 21265 previously unlisted companions, using information gathered by the ESO Quick Blue Survey. B1950 and J2000 system coordinates are given for each star. The magnitudes and spectral types are given in addition to the exact date of t…