%R 1996A&AS..115....1S
%J-9
%A Stickel M., Kuehr H.
%T The current optical identification status of the S5 radio source catalogue.
%F 1996.01.02
%B Optical identifications, magnitudes, and redshifts have been compiled for the 185 radio sources of the S5 catalogue, representing its current optical identification status. Reliable optical counterparts are found for more than 75% of the sources, nearly 50% of which have measured redshifts. Our tabulation also includes radio positions, radio fluxes, and radio spectral indices. References to other catalogues and detailed supplementary notes are given for a large fraction of
the sources.
%K catalogs - surveys - galaxies: active - quasars: general - radio continuum: galaxies; general

%R 1996A&AS..115...11S
%J-40
%A Stickel M., Kuehr H.
%T Optical identifications of radio sources from the 1Jy, S4 and S5 catalogues.
%F 1996.01.02
%B CCD images of the fields of 115 radio sources from the 1Jy, S4 and S5 catalogues are presented. New optical counterparts have been found for a total of 34 sources, a large fraction of which had as yet only been described as empty fields on Sky Survey Plates. Of the 54 radio sources with previously published identifications, 50 optical counterparts have been confirmed while for 4 sources new identifications are proposed. R band magnitudes, derived from the CCD images, are
provided for all but a few identified optical counterparts. The fields at the positions of 27 radio sources are still empty down to a limiting magnitude of at least m_R_=22mag, requiring much deeper optical as well as additional infrared images for establishing their optical counterparts.
%K catalogs - surveys - galaxies: active - quasars: general - radio continuum: general

%R 1996A&AS..115...41C
%J-57
%A Cutispoto G., Tagliaferri G., Pallavicini R., Pasquini L., Rodono M.
%T Photometric and spectroscopic studies of cool stars discovered in EXOSAT X-ray images. III. Photometric properties.
%F 1996.01.02
%B We present high-precision UBV(RI)_c_ photometry for a sample of active stars detected serendipitously by the EXOSAT satellite. Fourteen objects, out of 47 likely optical counterparts, turned out to be clearly variable, with periods in the range 1-8 days, including a newly discovered eclipsing binary. For most of them the optical variability is consistent with the presence of photospheric cool spots. We have used our multicolour photometry to estimate spectral
classifications and distances. The derived distances indicate that some of the observed stars are previously unidentified nearby (d<=25pc) M dwarfs. When combined with the results of high resolution spectroscopy, our photometric observations allow us to investigate the stellar content of the selected X-ray sample. Young stars and RS CVn-type binaries appear to constitute a large fraction of the selected sample.
%K stars: activity - stars: late-type - stars: variables - X-ray: stars

%R 1996A&AS..115...59T
%J-60
%A Thorel J.-C.
%T 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.
%F 1996.01.02
%B 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 of coherency in the Index) and the INput CAtalog Hipparcos (resolution of ambiguities on the binarity and on the position of
certain double stars which have seldom or never been observed again from the epoch or their discovery). The author has discovered three new binaries: JCT1, JCT2 and JCT3.
%K binaires visuelles - astrometrie  

%R 1996A&AS..115...61M
%J-74
%A Mitrou C.K., Doyle J.G., Mathioudakis M., Antonopoulou E.
%T The emission of the RS CVn binaries in the IRAS passbands.
%F 1996.01.02
%B In the literature, there is an ambiguity pertaining to the existence of a far-IR excess in RS CVn systems. In the current paper we undertook a study of the behaviour of 103 such systems in the IRAS passbands. We found 72 acceptable detections in the 12{mu}m band, and 40 in the 25{mu}m band (50% more than the IRAS Point Source Catalog). Although our findings may be interpreted as indicating towards the existence of an excess beyond 12{mu}m for some systems, the evidence
is not conclusive in all but two cases. These are systems GX Lib and HR 7428, with Capella being the only system where the IRAS fluxes in all four bands originate from the stellar photosphere. Given the accuracy of the data we did not find 12{mu}m excess for any system. We argue that the IRAS data alone cannot settle the issue, as their uncertainty is, in many cases, higher than what the Signal-to-Noise ratio of each observation implies. Furthermore, at the higher wavelength
bands the IRAS angular resolution drops from 0.5' at 12{mu}m to 2' at 100{mu}m and the background becomes very complex, so one cannot be certain about the origin of the observed flux. The existence of IR excess in the RS CVn stars is important as far as the evolutionary scenarios for these systems are concerned. Future missions such as the Infrared Space Observatory will return more sensitive and accurate measurements and the ambiguity can be removed. The fluxes we quote
will be helpful when planning these future observations, as we provide more accurate photometry and for a larger selection of sources than the IRAS Point Source Catalog.
%K binaries: close - circumstellar matter - infrared: stars

%R 1996A&AS..115...75C
%J-79
%A Costa E., Loyola P.
%T Optical astrometry of Benchmark radio sources. III. Positions of 35 southern extragalactic radio sources with respect to the International Reference Stars catalogue.
%F 1996.01.02
%B Optical positions, relative to the International Reference Stars catalogue (IRS), and therefore in the system of the FK5, have been obtained for the optical counterparts of 35 extragalactic radio sources south of {delta}~+3deg . Many of these sources are being considered as possible Benchmark objects for the establishment of a quasi-inertial unified radio/optical reference frame. Precision levels better than 0.2" in both coordinates were achieved. A comparison with VLBI
radio positions available for these sources is presented. We give evidence for a possible offset in RA between the radio and optical reference frames.
%K astrometry - radio continuum: stars - reference system - quasars: individual: QSO 0523-570

%R 1996A&AS..115...81B
%J-95
%A Bronfman L., Nyman L.-A, May J.
%T A CS(2-1) survey of IRAS point sources with color characteristics of ultra-compact HII regions.
%F 1996.01.02
%B We have made a complete survey of the CS(2-1) emission toward IRAS point sources in the galactic plane. The sources observed were selected according to their far infrared (FIR) colors, which are characteristic of UC HII regions. They have 25{mu}m/12{mu}m flux ratios larger than 3.7 and 60{mu}m/12{mu}m flux ratios larger than 19.3. The survey covered a region from b=-2deg to b=2deg from l=300deg to l=0deg and from l=0deg to l=60deg, and from b=-4deg to
b=4deg elsewhere. We detected 843 sources out of 1427 sources observed. The distributions of detected and undetected sources in a FIR color-color diagram show some differences, suggesting that more than one type of object is present in our observed sample.
%K Galaxy: structure - infrared: interstellar: continuum - interstellar medium: clouds - interstellar medium: HII regions - interstellar medium: molecules - radio lines: molecular

%R 1996A&AS..115...97V
%J-115
%A Veron-Cetty M.-P., Veron P.
%T Astrometry with the Digitized Sky Survey. Positions of 790 AGNs.
%F 1996.01.02
%B From the measurement on the Digitized Sky Survey of the optical position of 153 QSOs with an accurate absolute VLBI position, we have determined that the rms uncertainty of these measurements is ~0.6arcsec in both coordinates over the whole sky, except for objects located near one edge of the plate. We have measured the optical position of 790 AGNs (or AGN candidates). For many of these objects, the accuracy of the published optical position was 1 arcmin or worst.
%K astrometry - galaxies: active - quasars

%R 1996A&AS..115..117C
%J-149
%A Cho S.-H., Kaifu N., Ukita N.
%T SiO maser survey of late-type stars. I. Simultaneous observations of six transitions of ^28^SiO and ^29^SiO.
%F 1996.01.02
%B Simultaneous observations of the ^28^SiO v=0, 1, 2, and 3, J=1-0 and ^29^SiO v=0 and 1, J=1-0 transitions for 102 late-type stars were made with a sensitivity of about 2Jy at the 3{sigma} level using the 45 m telescope of Nobeyama Radio Observatory (NRO). SiO maser emission was detected in 83 stars; seven of them being new detections. The v=3 maser was detected in 12 stars with eight new detections. Most of the v=3 masers occur at the same radial velocity of the
strongest spikes of the v=1 and 2 masers. We also newly found the ^29^SiO v=0 maser in six stars. The ^29^SiO v=0 line is stronger and narrower than the ^28^SiO v=0 line, indicating that the ^29^SiO line is masing. In most cases, the ^29^SiO line shows a single narrow profile (FWHM=1 to 3km/s), with peak radial velocities coincident with the stellar velocity derived from OH maser and/or SiO/CO thermal lines within 1km/s. Therefore, this maser line provides excellent
means to measure the stellar velocities of late-type stars. The ^28^SiO v=0, J=1-0 line was detected in eleven stars, with three new detections.
%K masers - stars: AGB, post-AGB; circumstellar matter

%R 1996A&AS..115..151S
%J-159
%A Saraph H.E., Storey P.J.
%T Atomic data from the IRON Project. XI. The ^2^P^o^_1/ 2_-^2^P^o^_3/2_ fine-structure lines of Ar VI, K VII and Ca VIII.
%F 1996.01.02
%B We give collision strengths and collision rates for electron excitation of the ^2^P^o^_1/2_-^2^P^o^_3/2_ fine-structure transitions in the aluminium-like ions Ar VI, K VII and Ca VIII, at 4.53, 3.19 and 2.32{mu} respectively. The ground configuration of ions in the aluminium sequence has three electrons in the M-shell. Electron correlation effects are very strong in these ions because the subshells are energetically very close. They manifest themselves in large resonance
structures that dominate the collision strengths. The accuracy of calculated collision rates depends critically on the accuracy with which the positions and shapes of these resonances are determined. This paper is a first attempt to provide collision rates for aluminium sequence ions that have been calculated taking full account of these electron correlation effects.
%K atomic data - atomic processes

%R 1996A&AS..115..161M
%J-174
%A Malbet F.
%T High angular resolution coronography for adaptive optics.
%F 1996.01.02
%B Recent adaptive optics systems in astronomy achieve high-angular resolution. With the extreme stability of the images, detection at very low fluxes can be reached using a coronograph at the diffraction limit of the telescopes. This paper is an overview of the issues of stellar coronography used at the diffraction limit. Image formation through such a system is illustrated by numerical simulations. The description of a coronograph implemented on the VLT adaptive optics
prototype, COME-ON, is presented as well as the first observations.
%K instrumentation: miscellaneous - techniques: miscellaneous - stars: imaging - atmospheric effects

%R 1996A&AS..115..175R
%J-179
%A Ragazzoni R., Marchetti E., Claudi R.U.
%T Magnetic driven liquid mirrors in orbiting telescopes.
%F 1996.01.02
%B In space a ferro-magnetic liquid can be confined in a region through electromagnetic forces. The surface of the liquid can be used as a concave mirror for astronomical purposes. A description of the technique and of the problems related is given, together with some cases studied for different classes of telescopes.
%K telescopes - space vehicles

%R 1996A&AS..115..181H
%J-188
%A Hunt L.K., Lisi F., Testi L., Baffa C., Borelli S., Maiolino R., Moriondo G., Stanga R.M.
%T ARNICA, the Arcetri near-infrared camera: Astronomical performance assessment.
%F 1996.01.02
%B The Arcetri near-infrared camera ARNICA was built as a users' instrument for the Infrared Telescope at Gornergrat (TIRGO), and is based on a 256x256 NICMOS 3 detector. In this paper, we discuss ARNICA's optical and astronomical performance at the TIRGO and at the William Herschel Telescope on La Palma. Optical performance is evaluated in terms of plate scale, distortion, point spread function, and ghosting. Astronomical performance is characterized by camera efficiency,
sensitivity, and spatial uniformity of the photometry.
%K infrared: general - techniques: photometric - instrumentation: detectors

%R 1996A&AS..115..189H
%J-193
%A Haindl M., Simberova S.
%T A high-resolution radiospectrograph image reconstruction method.
%F 1996.01.02
%B A new type of image reconstruction method is introduced. The image reconstruction is based on an adaptive regression type of destriping method using a regression model prediction for replacing a corrupted image row representing a frequency channel or isolated pixels. The method uses available information from the pixels next to the corrupted ones thanks to the spatial correlation of the radiospectrograph data. The method suggested can be successfully applied also to other
image acquisition and processing applications, i.e. remote sensing, pattern recognition, meteorology, medicine, etc.
%K techniques: image processing; spectroscopic - Sun: radio radiation

%R 1996A&AS..115..195S
%J-207
%A Serra-Ricart M., Gaitan V., Garrido Ll., Perez-Fournon I.
%T Faint object classification using Artificial Neural Networks.
%F 1996.01.02
%B We propose a method to classify faint objects from digital astronomical images based on a layered feedforward neural network which has been trained by the backpropagation procedure (Werbos 1974). An "academic" example showing that artificial neural network method behaves as a Bayesian classifier is discussed. A comparison of the classification results obtained from simulated data by the neural network classifier and by the well-established resolution classifier (Valdes
1982a) is performed in order to assess the reliability and limitations of the neural network classifier. A similar behaviour, up to the same faintness limit to which the resolution classifier works, is found in both classifiers. The method proposed in this paper offers a clear advantage, in terms of speed, over traditional methods in the classification of large samples of data; it allows a uniform and objective classification of large amounts of astronomical data in short
computing times, which is useful for the analysis of astronomical observations with high data rates.
%K method: data analysis; image processing