Astronomy and Astrophysics Supplement Series

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List of Papers (Total 2,129)

Phase calibration scheme for a "T” array

A calibration scheme based on closure and redundancy techniques is described for correcting the phase errors in the complex visibilities observed with a T-shaped radio interferometer array. Practical details of the scheme are illustrated with reference to the Gauribidanur radioheliograph (GRH).

Hydrogen content in Kazarian galaxies

Several H I related astrophysical parameters such as neutral hydrogen total mass and hydrogen mean projected density, indicative total mass as well as usual ratios , and for 23 galaxies from Kazarian lists are derived. Their variation ranges are rather wide almost coinciding with those for normal galaxies belonging to the same morphological types. Kazarian galaxies do not...

Stark broadening of neutral zinc spectral lines

Using the semiclassical perturbation approach, we have calculated electron-, pro ton- and He II-impact line widths and shifts for 32 Zn I multiplets as a function of temperature and perturber density. Obtained results have been compared with the existing theoretical and experimental data.

A survey of UV-excess AGNs in the South Galactic Pole - A sample for the analysis of the QSO clustering

Spectra, position, magnitudes and colors are presented for 485 faint () emission line objects selected with the ultraviolet-excess (UVX) criterion on a area of 24.6 deg2 in the South Galactic Pole. The objects were selected from the analysis of pixel-to-pixel stacking of COSMOS scans of UKST U J and R plates. The candidates were observed with the Meudon-ESO Fiber Optics System...

Contribution à l'étude des spectres composites - VIII. HD 174016-7, une étoile Ap associée à une géante G Contribution to the study of composite spectra VIII. HD 174016-7, an Ap star with a giant G

HD 174016-7, listed by [Hynek (1938)] as a star having a composite spectrum, was on our observing programmes of such objects carried out both at the Cambridge Observatories and at the Observatoire Midi-Pyrénées. Most of the observations were made with the CORAVEL spectrovelocimeter of the Swiss telescope at the Observatoire de Haute-Provence. We find that this star is a long...

An absolute calibration of DENIS (deep near infrared southern sky survey)

An absolute calibration of the DENIS photometric system is presented. It includes the determination of the overall transmission profiles in the 3 bands, namely i, J and Ks, combining contributions from atmosphere, telescope mirrors, instrument lenses and dichroics, filters, and detectors. From these normalized profiles, isophotal and effective wavelengths are computed, using the...

Interferometric imaging tests for the Large Binocular Telescope

We present an experiment of interferometric imaging for the Large Binocular Telescope (LBT), conducted at the 1.5 m TIRGO infrared telescope. The raw data were produced by simulating the LBT pupil with a mask on the secondary mirror. Two different conditions of , where is the single aperture diameter and the Fried parameter, were simulated by the choice of ; field rotation was...

HI observations of nearby galaxies - I. The first list of the Karachentsev catalog

We present HI observations of the galaxies in the first list of the Karachentsev catalog of previously unknown nearby dwarf galaxies (Karachentseva & Karachentsev 1998). This survey covers all known nearby galaxy groups within the Local Volume (i.e. within 10 Mpc) and their environment, that is about 25% of the total sky. A total of 257 galaxies have been observed with a...

Estimating the point spread function of the adaptive optics system ADONIS using the wavefront sensor measurements

Adaptive Optics (AO) has been developed to compensate the wavefront deformation due to the atmospheric turbulence. The wavefront correction, however, is often only partial and a residual blur is present in a long exposure image. It is therefore important to deconvolve the image to do accurate photometry or to detect faint structures. For this, the point spread function (PSF) has...

Relative figure of merit of optical interferometry and spectroscopy - Example of parameter estimates of P Cygni circumstellar envelope

When planning new facilities, one is interested to know whether and by how much the new technique is superior to already existing ones. We describe a general approach permitting us to evaluate the relative merits of various techniques used in astrophysical observations, following the theory of model parameter estimation. It is applied to compare two-aperture optical long baseline...

The ionized gas in the spiral galaxy NGC 3359 - II. Kinematics

The spiral galaxy NGC 3359 has been observed in the Hα line with the TAURUS II Fabry-Perot interferometer at the William Herschel Telescope within the BARS programme on the Canary Island telescopes in order to study the kinematics of the ionized gas.
We have produced maps of velocity and velocity dispersion, and computed the rotation curve out to ~ 3 scale lengths from the centre...

Optical polarization of 47 quasi-stellar objects: The data

New broad-band linear polarization measurements are presented for a sample of 47 QSOs which includes 27 broad absorption line QSOs and 2 gravitational lens candidates.

Search and discovery tools for astronomical on-line resources and services

A growing number of astronomical resources and data or information services are made available through the Internet. However valuable information is frequently hidden in a deluge of non-pertinent or non up-to-date documents. At a first level, compilations of astronomical resources provide help for selecting relevant sites. Combining yellow-page services and meta-databases of...

Micrometer measurements of double stars made at the Côte D'Azur and Calar Alto observatories

We report 312 micrometer measurements of 155 visual double stars made with the 50 cm refractor at the Côte D'Azur observatory (Nice, France) and with the 152 cm telescope at Calar Alto observatory (Almería, Spain).

Atomic data from the IRON Project - XLII. Electron impact excitation of Fe xxi

Collision strengths and collisional rate parameters are provided for transitions among the and 2p levels of C-like Fe xxi. The data have been computed in a 52-state Breit-Pauli approximation thus accounting for the most prominent relativistic effects. An R-matrix close-coupling calculation comprising partial wave contributions up to and of order 8000 energy points in the range up...

Tuorla quasar monitoring

We present results of optical monitoring of quasars and blazars obtained at Tuorla Observatory between September 1995 and May 1997. The aim of our monitoring is to provide well sampled optical light curves for quasar and blazar studies. During the observing period the V-band brightness of S2 0109+224, 3C 66A, and ON 231 (W Comae) reached some of the brightest values ever measured...

Hipparcos astrometry for 257 stars using Tycho-2 data

We present improved Hipparcos astrometry for 257 Hipparcos stars, resolved into 342 components. For 64 of the stars no astrometry was obtained in the Hipparcos Catalogue, while for the remaining stars additional components have been added by this solution or the positions have been revised considerably. We have used the published Hipparcos transit data for the new solutions...

Polarization for pair annihilation in strong magnetic fields

We derive the cross-section for one-quantum annihilation of polarized electrons and positrons. The electron and positron can occupy arbitrary Landau levels and have non-zero momentum parallel to the field, and the cross-section is calculated for any polarization of the radiation. When we take zero parallel momentum for the electron and sum over photon polarization we obtain...

A revised catalogue of δ Sct stars

An extensive and up-dated list of δ Sct stars is presented here. More than 500 papers, published during the last few years, have been revised and 341 new variables have been added to our last list, six years ago. This catalogue is intended to be a comprehensive review on the observational characteristics of all the δ Sct stars known until now, including stars contained in earlier...

Strömgren and Hβ photometry of O and B type stars in star-forming regions - III. Carina Spiral Feature

Strömgren and Hβ photometry of O and B type stars, generally brighter than 9.5 mag is reported for the field of the Carina Spiral Feature. The observations are based on the PPM catalogue identifications and are designed to improve the completeness of the existing data for the bright early-type stars in the field. We present new uvby photometry for 283 stars and Hβ photometry for...

Detection of scattered light in telescopes

We present a simple, but powerful method to test for the presence of scattered light in telescopes. Scattered light can seriously hamper any attempt to achieve a proper flat fielding of CCD data. The method consists of making a pinhole camera (camera obscura) by placing a pinhole mask in front of the CCD window. Exposing the CCD in this configuration gives an image of the light...

Time variability of five strong 12 GHz methanol masers

Five intense 12 GHz methanol masers with structured profile have been monitored during the period 90 Nov.-92 Apr., in order to study the variability on time scales ranging from one week to about 2 years. The integrated flux density of W3(OH), G188.94 +0.89, NGC 7538 remains constant (within the measurement uncertainties) during our period of observation. By amplitude...

VRI photometry of stars in the fields of 12 BL Lacertae objects

We present VRc Ic Johnson-Cousins magnitudes of field comparison stars for twelve BL Lacertae objects belonging to the largest sample of blazars which is monitored at the Perugia University Observatory. The sequences reported here can be used in the long–term CCD photometric monitoring of BL Lac objects aimed to understand the characteristics of their variability. Finding charts...

TU Bootis: An ambiguous W Ursae Majoris system

The W UMa system TU Boo has a period of 0.32438 days and a spectral type G3. We present here the first photometric analysis, based on photoelectric B and V light curves. The q-search method was used to find the preliminary range of the mass-ratio in order to search for the final solution. The unspotted solution was found by using the unperturbed part of the light curve and...

B[e] stars. I. HD 51585 (=OY Gem)

We analyse CCD spectroscopic material obtained at the Haute Provence Observatory between 1990 and 1993, covering the wavelength region 3800-11000 Å. 320 emission lines were measured and identified. Of these about 40% correspond to permitted or forbidden lines of ionized iron. Many forbidden lines (20% of the total) are present, including many classic nebular lines. We also...