%R 2000A&AS..147..169B
%J-173
%A Bicay M.D.
%A Stepanian J.A.
%A Chavushyan V.H.
%A Erastova L.K.
%A Ayvazyan V.T.
%A Seal J.
%A Kojoian G.
%T Accurate optical positions for 2978 objects from the Second Byurakan Survey (SBS) with the Digitized Sky Survey.
%M ds1535
%F 2000.11.20
%B Optical positions of 2978 objects listed in the Second Byurakan Survey (SBS) were obtained using the Digitized Sky Survey (DSS), and are given with an rms uncertainty ~1 arcsec in each coordinate.
%K surveys - catalogs - galaxies: active - quasars

%R 2000A&AS..147..175B
%J-180
%A Bachev R.
%A Strigachev A.
%A Dimitrov V.
%T VRI comparison stars for selected active galaxies.
%M ds1887
%F 2000.11.20
%B We present V (Johnson) and RI (Cousins) magnitudes of field comparison stars for 12 bright Seyfert galaxies. These stars are closer than 6' (typically 3'-4') to the galaxy and have V magnitudes between 10mag and 6mag. The sequences could be used for CCD monitoring and differential photometry of these active galaxies, aimed to better understanding the physics of their variability. Photometric errors of measured stars are in the range 0.03mag-0.06mag . Finding charts (15'x15') are also included.
%K galaxies: Seyfert

%R 2000A&AS..147..181S
%J-185
%A Szymczak M.
%A Kus A.J.
%T New detections of OH sources towards the 6.7 GHz methanol masers.
%M ds1895
%F 2000.11.20
%B A sample of 6.7GHz methanol masers has been searched for OH maser emission at 1665 and 1667 MHz using the 32 m Torun radio telescope. Eight new OH sources were detected. They are generally weak at radio and infrared wavelengths. In the northern hemisphere sample of 68 methanol sources the OH maser emission is associated with 49 sources. Generally OH masers do not arise in weak FIR sources. The ratio of OH to CH_3_OH maser flux densities increases for objects with blue FIR
colour and probably reflects evolutionary changes in the star-forming regions.
%K masers - surveys - stars: formation - ISM: molecules - radio lines: ISM - HII regions

%R 2000A&AS..147..187H
%J-194
%A Huchtmeier W.K.
%A Karachentsev I.D.
%A Karachentseva V.E.
%T HI observations of nearby galaxies. II. The second list of the Karachentsev catalog.
%M ds1917
%F 2000.11.20
%B We present HI observations of the galaxies in the second list of the Karachentsev catalog of previously unknown nearby dwarf galaxies (Karachentseva et al., 1999A&AS..135..221K). This survey covers an area of 6000 square degrees within the boundaries RA [14h, 23h30] and DE [-20{deg}, +60{deg}] including the nearest cosmic void: RA = 18^h^38^m^, DE = +18{deg}, V_0_<=1500km/s. A total of 78 galaxies have been observed with a detection rate of 42%. We searched a frequency band
corresponding to heliocentric radial velocities from -470km/s to +3970km/s. Non-detections are either due to limited coverage in radial velocity, confusion with Local HI (mainly in the velocity range -140km/s to +20km/s), or lack of sensitivity for very weak emission. In the general direction toward the Local Void we detected only one galaxy with a corrected radial velocity below 1500km/s. The Local Void seems to be highly deficient in dwarf galaxies.
%K galaxies: distances and redshift - dwarft - fundamental parameters - general

%R 2000A&AS..147..195M
%J-203
%A Maron O.
%A Kijak J.
%A Kramer M.
%A Wielebinski R.
%T Pulsar spectra of radio emission.
%M h2144
%F 2000.11.20
%B We have collected pulsar flux density observations and compiled spectra of 281 objects. The database of Lorimer et al. (1995MNRAS.273..411L) has been extended to frequencies higher than 1.4GHz and lower than 300MHz. Our results show that above 100 MHz the spectra of the majority of pulsars can be described by a simple power law with average value of spectral index <{alpha}>=-1.8+/-0.2. A rigorous analysis of spectral fitting revealed only about 10% of spectra which can be modelled by
the two power law. Thus, it seems that single power law is a rule and the two power law spectrum is a rather rare exception, of an unknown origin, to this rule. We have recognized a small number of pulsars with almost flat spectrum ({alpha}>=-1.0) in the wide frequency range (from 300MHz to 20GHz) as well as few pulsars with a turn-over at unusually high frequency (~1GHz).
%K pulsars: general - radiation mechanisms: non-thermal

%R 2000A&AS..147..205C
%J-228
%A Cincotta P.M.
%A Simo C.
%T Simple tools to study global dynamics in non-axisymmetric galactic potentials - I.
%M h1686
%F 2000.11.20
%B In a first part we discuss the well-known problem of the motion of a star in a general non-axisymmetric 2D galactic potential by means of a very simple but almost universal system: the pendulum model. It is shown that both loop and box families of orbits arise as a natural consequence of the dynamics of the pendulum. An approximate invariant of motion is derived. A critical value of the latter sharply separates the domains of loops and boxes and a very simple computation
allows to get a clear picture of the distribution of orbits on a given energy surface. Besides, a geometrical representation of the global phase space using the natural surface of section for the problem, the 2D sphere, is presented. This provides a better visualization of the dynamics. In a second part we introduce a new indicator of the basic dynamics, the Mean Exponential Growth factor of Nearby Orbits (MEGNO), that is suitable to investigate the phase space structure
associated to a general Hamiltonian. When applied to the 2D logarithmic potential it is shown to be effective to obtain a picture of the global dynamics and, also, to derive good estimates of the largest Lyapunov characteristic number in realistic physical times. Comparisons with other techniques reveal that the MEGNO provides more information about the dynamics in the phase space than other wide used tools. Finally, we discuss the structure of the phase space associated to
the 2D logarithmic potential for several values of the semiaxis ratio and energy. We focus our attention on the stability analysis of the principal periodic orbits and on the chaotic component. We obtain critical energy values for which connections between the main stochastic zones take place. In any case, the whole chaotic domain appears to be always confined to narrow filaments, with a Lyapunov time about three characteristic periods.
%K galaxies: dynamics - stellar dynamics - methods: analytical-numerical - chaos

%R 2000A&AS..147..229B
%J-242
%A Banerjee D.P.K.
%A Rawat S.D.
%A Janardhan P.
%T H{alpha} observations of Be stars.
%M h2226
%F 2000.11.20
%B We present here the H{alpha} spectra of 44 Be stars taken at a resolution of 0.5 {AA}. From the spectra, different emission line parameters have been deduced. A study of the correlations between different pairs of these parameters has been made with a view to understanding the mechanisms of line formation and shaping in Be stars.
%K Be stars - spectroscopy - line profiles

%R 2000A&AS..147..243W
%J-249
%A Wolf M.
%A Molik P.
%A Hornoch K.
%A Sarounova L.
%T Period changes in W UMa-type eclipsing binaries: DK Cygni, V401 Cygni, AD Phoenicis and Y Sextantis.
%M ds10133
%F 2000.11.20
%B We present a period analysis of the four well-known W UMa-type eclipsing binaries DK Cyg (P=0.47d), V401 Cyg (0.58d), AD Phe (0.38d) and Y Sex (0.42d). Several new times of minimum light, recorded photoelectrically, have been gathered. Analysis of all available eclipse timings of the DK Cygni and V401 Cygni has confirmed a significant increase in period of 1.15x10^-10^ and 1.48x10^-10^day/cycle, respectively. A simultaneous solution of the B, V and R light
curves was computed for V401 Cyg using the Binary Maker 2.0 synthetic lightcurve software. This solution indicates that V401 Cyg is in contact with a filing factor of 46%. The period of AD Phe seems to be constant. Period changes of Y Sex could be explain by a light-time effect caused by a third body in an eccentric orbit with a period of 58 years.
%K stars: binaries: eclipsing - stars: individual: DK Cyg - stars: individual: V401 Cyg - stars: individual: AD Phe - stars: individual: Y Sex - stars: fundamental parameters

%R 2000A&AS..147..251T
%J-251
%A Thorel J.-C.
%T Nice observatory measurements of double stars (3rd series).
%M ds1899
%F 2000.11.20
%B We present recent measurements of visual double stars made at the Nice Observatory (3rd series). We also report the discovery of a new double star: JCT 4. Moreover we give a more precise position of the double star DOO 35.
%K astrometry, binaries: visual

%R 2000A&AS..147..253N
%J-270
%A Nahar S.N.
%T Atomic data from the Iron Project. XLV. Relativistic transition probabilities for carbon-like Ar XIII and Fe XXI using Breit-Pauli R-matrix method.
%M ds1909
%F 2000.11.20
%B The Breit-Pauli R-matrix method developed under the Iron Project has been used to obtain extensive sets of oscillator strengths and transition probabilities for dipole allowed and intercombination fine structure transitions in carbon like ions, Ar XIII and Fe XXI. The complete set consists of 1274 fine structure bound energy levels and 198259 oscillator strengths for Ar XIII, and 1611 bound levels and 300079 oscillator strengths for Fe XXI. These correspond to levels of
total angular momenta of 0<=J<=7 of even and odd parities formed from total spin of 2S+1=5, 3, 1, and orbital angular momenta 0<=L<=9 with n<=10, 0<=l<=9 for each ion. The relativistic effects are included in the Breit-Pauli approximation. The close coupling wavefunction expansion for each ion is represented by the lowest 15 fine structure levels of target configurations, 2s^2^2p, 2s2p^2^ and 2p^3^. The energy levels are identified spectroscopically using a newly
developed identification procedure. The procedure also makes a correspondence between the fine structure energy levels and LS terms. This provides the check for completeness of the calculated levels. Comparison is made of the present energies and the f-values with the available observed and theoretical values. Present transition probabilities agree very well with the relativistic atomic structure calculations of Mendoza et al. for the intercombination transitions,
2s2p^3^(^5^S{deg}_2_) - 2s^2^2p^2^(^3^P_1,2_,^1^D_2_). This further indicates that the importance of the neglected Breit interaction decreases with ion charge and constrains the uncertainty in the present calculations to within 15% even for the weak transitions.
%K atomic data

%R 2000A&AS..147..271J
%J-284
%A Jabiri A.
%A Benkhaldoun Z.
%A Vernin J.
%A Munoz-Tunon C.
%T A meteorological and photometric study of the Oukaimeden site. Comparison with the Observatorio del Roque de los Muchachos using Carlsberg Automatic Meridian Circle data.
%M ds1856
%F 2000.11.20
%B In this paper, we present meteorological and photometric studies of the Oukaimeden astronomical site in Morocco. The meteorological measurements were obtained over 537 days. The photometric data were measured by both FIP and GONG instruments over 1182 days. We have also analysed the weather parameters at the Observatorio del Roque de los Muchachos (ORM) in the Canary Islands. More than ten years of measurements with the Carlsberg Automatic Meridian Circle (CAMC) are
included, corresponding to 2931 nights of atmospheric extinction measurements. These different data sets demonstrate photometric sky quality, wind speed and direction, local relative humidity, temperature and other parameters, such as the barometric pressure at the ORM and the precipitation at Oukaimeden. We have separated the day- and night-time data to provide information relevant to solar and stellar observations. Data from the Oukaimeden site have been compared to the ORM
site, recognized as one of the best astronomical sites in the world and the results from our data confirm that Oukaimeden constitutes an excellent potential site for astronomical observations.
%K site testing

%R 2000A&AS..147..285P
%J-290
%A Pedretti E.
%A Labeyrie A.
%A Arnold L.
%A Thureau N.
%A Lardiere O.
%A Boccaletti A.
%A Riaud P.
%T First images on the sky from a hyper telescope.
%M ds9868
%F 2000.11.20
%B We show star images obtained with a miniature ``densified pupil imaging interferometer'' also called a hyper-telescope. The formation of such images violates a ``golden rule of imaging interferometers'' which appeared to forbid the use of interferometric arrangements differing from a Fizeau interferometer. These produce useless images when the sub-apertures spacing is much wider than their size, owing to diffraction through the sub-apertures. The hyper-telescope
arrangement solves these problems opening the way towards multi-kilometer imaging arrays in space. We experimentally obtain an intensity gain of 24+/-3x when a densified-pupil interferometer is compared to an equivalent Fizeau-type interferometer and show images of the double star {alpha} Gem. The initial results presented confirm the possibility of directly obtaining high resolution and high dynamic range images in the recombined focal plane of a large interferometer if
enough elements are used.
%K interferometers - double star images - laboratory images - pupil densification

%R 2000A&AS..147..291V
%J-297
%A Villar-Martin M.
%A Alonso-Herrero A.
%A di Serego Alighieri S.
%A Vernet J.
%T Interpreting the kinematics of the extended gas in distant radiogalaxies from 8-10 m telescope spectra.
%M ds1884
%F 2000.11.20
%B The nature of the extreme kinematics in the extended gas of distant radio galaxies (z>0.7) is still an open question. With the advent of the 8-10m telescope generation and the development of NIR arrays we are in the position for the first time to develop a more detailed study by using lines other than Ly{alpha} and [OII]{lambda}3727 depending on redshift. In this paper we review the main sources of uncertainty in the interpretation of the emission line kinematics: the
presence of several kinematic components, Ly{alpha} absorption by neutral gas/dust and the contribution of scattered light to some of the lines. As an example, several kinematic components can produce apparent, false rotation curves. We propose methods to solve these uncertainties. We propose to extend the methods applied to low redshift radio galaxies to investigate the nature of the kinematics in distant radio galaxies: by means of the spectral decomposition of the strong
optical emission lines (redshifted into the NIR) we can isolate the different kinematic components and study the emission line ratios for the individual components. If shocks are responsible for the extreme kinematics, we should be able to isolate a kinematic component (the shocked gas) with large FWHM (>=900km/s), low ionization level [OIII]{lambda}5007/H{beta}~2-4 and weak HeII{lambda}4686/H{beta}<=0.07, together with a narrow component (<= few hundred km/s) with
higher ionization level and strong HeII emission (HeII/H{beta}~0.5). 
%K techniques: spectroscopic - methods: observational - galaxies, kinematics and dynamics

%R 2000A&AS..147..299G
%J-321
%A Griffin R.E.M.
%A David M.
%A Verschueren W.
%T Accuracy of radial-velocity measurements for early-type stars. II. Investigations of spectrum mismatch from high-resolution observations
%M h2265
%F 2000.11.20
%B The accuracy with which radial velocities of early-type stars can be measured is limited in practice by the existence of asymmetrical differences between object and template spectrum, constituting ``spectrum mismatch''. Our studies of the magnitude of spectrum-mismatch errors, commenced in Paper I (Verschueren et al., 1999A&AS..136..591V) on the basis of synthetic spectra having different attributes of effective temperature (T_eff_) and logg, are continued here in a complementary approach
that employs observed spectra. From over 60 de-archived observations we derive accurate wavelength scales for the spectra of 16 dwarfs of spectral types B8-F7, and examine the results of cross-correlating the spectra against different (observed) template spectra. We also test the effects of (a) truncating the spectra at different levels below the continuum, (b) adding rotational broadening to enforce a visual match of line-width between object and template, (c) applying
rotational broadening to exacerbate a rotational mismatch, and (d) neglecting the presence of faint companion spectra. We also cross-correlate pairs of spectra such that the differences between their T_eff_ are minimal. We conclude that it will be possible to measure radial velocities to an accuracy considerably better than 1km/s for slowly-rotating stars in the range of spectral types examined, and a careful discussion of the nature and sources of the random and
systematic errors that become significant in work of this nature enables us to specify conditions that are important for achieving such accuracy routinely. We find that both rotational broadening, and the star-to-star variations in line strengths that are so prevelant among A-type spectra, can give rise to more deleterious mismatch shifts (RV errors) than do differences in T_eff_ alone, even for {Delta}T_eff_ as great as 300-400K. By intercomparing the results given by wide
regions of spectrum (~800{AA}) with those obtained by isolating small groups of features in very narrow windows (~30{AA}), we have been able to designate a window near {lambda}4570{AA} that should be particularly reliable for high-accuracy results, and we propose further studies at very high S/N ratio in that specific window to complement and extend the results of the present paper.
%K techniques: radial velocities - techniques: spectroscopic - stars: early-type

%R 2000A&AS..147..323B
%J-333
%A Bertero M.
%A Boccacci P.
%T Image restoration methods for the Large Binocular Telescope (LBT).
%M h2212
%F 2000.11.20
%B A complete exploitation of the imaging properties of the Large Binocular Telescope (LBT) will require a generalization of the restoration methods which apply to the case of a single image. Several different observations must be combined to obtain a high-resolution representation of a given target. The purpose of this paper is to extend to this problem some of the most used restoration methods, including linear methods such as Tikhonov regularization as well as iterative
regularization methods providing positive solution. The proposed methods are implemented and tested on simulated LBT images of diffuse and point-like objects. The results are discussed both from the point of view of the accuracy and from that of the computational efficiency, because LBT images may contain, in principle, up to 10^8^ pixels.
%K data analysis - methods numerical - image processing - telescopes

%R 2000A&AS..147..335D
%J-346
%A Diolaiti E.
%A Bendinelli O.
%A Bonaccini D.
%A Close L.
%A Currie D.
%A Parmeggiani G.
%T Analysis of isoplanatic high resolution stellar fields. by the StarFinder code
%M ds1908
%F 2000.11.20
%B We describe a new code for the deep analysis of stellar fields, designed for Adaptive Optics (AO) Nyquist-sampled images with high and low Strehl ratio. The Point Spread Function (PSF) is extracted directly from the image frame, to take into account the actual structure of the instrumental response and the atmospheric effects. The code is written in IDL language and organized in the form of a self-contained widget-based application, provided with a series of tools for data
visualization and analysis. A description of the method and some applications to AO data are presented.
%K instrumentation: adaptive optics - method: data analysis - techniques: image processing - techniques: photometric - astrometry - stars: imaging

%R 2000A&AS..147..347V
%J-359
%A Vondrak J.
%A Cepek A.
%T Combined smoothing method and its use in combining Earth orientation parameters measured by space techniques.
%M ds9736
%F 2000.11.20
%B The new combined method of smoothing observational data, being a generalization of the Whittaker-Robinson-Vondrak method based on probability, is designed. Its objective is to remove the high-frequency noise present in the observations of an (analytically unknown) time function and its first derivatives. The method consists in finding a weighted compromise among three different conditions: smoothness of the searched curve, its fidelity to the observed function values and
its fidelity to the observed first time derivatives. The method assumes that the observations are distributed non-uniformly, with different uncertainties, and that the epochs of both input series containing the observed function values and first derivatives are not identical. Its possibilities are demonstrated on combining both simulated data and the Earth orientation parameters observed by different space techniques: Very Long Baseline Interferometry and Global Positioning
System, namely the Universal Time/length of day changes and polar motion/polar motion rate.
%K methods: numerical - techniques: miscellaneous - reference systems