%R 1999A&AS..137....1Q
%J-5
%A Qiao R.C., Shen K.X., Liu J.R., Harper D.
%T 1994-1996 CCD astrometric observations of Saturn's satellites and comparison with theories.
%M ds7914
%F 1999.05.18
%B In this paper, we publish 451 measurements of positions of the major satellites of Saturn made in 1994, 1995 and 1996 using a CCD detector attached to the 1.56 m reflector at the Sheshan Station near Shanghai. The observations we have made include the seven major satellites exclusive of the outermost satellite Iapetus. In our implementation the four contemporary theories were used for astrometric calibration of the CCD. Analysis of the data as inter-satellite positions
shows that these observations of Tethys, Dione, Rhea and Titan have rms residuals of 0.08 arcsec, which are comparable in quality to the observations made by Harper et al. (1997A&AS..121...65H). For the faint satellites including Mimas, Enceladus and Hyperion we have also obtained the observations in equivalent precision to the photographic observations.
%K planets and satellites: satellites of saturn - astrometry

%R 1999A&AS..137....7R
%J-19
%A Roger R.S., Costain C.H., Landecker T.L., Swerdlyk C.M.
%T The radio emission from the Galaxy at 22 MHz.
%M ds1640
%F 1999.05.18
%B We present maps of the 22MHz radio emission between declinations -28{deg} and +80{deg}, covering ~73% of the sky, derived from observations with the 22 MHz radiotelescope at the Dominion Radio Astrophysical Observatory (DRAO). The resolution of the telescope (EWxNS) is 1.1{deg}x1.7{deg} secant (zenith angle). The maps show the large scale features of the emission from the Galaxy including the thick non-thermal disk, the North Polar Spur (NPS) and absorption due to
discrete HII regions and to an extended band of thermal electrons within 40{deg} of the Galactic centre. We give the flux densities of nine extended supernova remnants shown on the maps. A comparison of the maps with the 408-MHz survey of Haslam et al. (1982A&AS...47....1H) shows a remarkable uniformity of spectral index (T{prop.to}{nu}^-{beta}^) of most of the Galactic emission, with {beta} in the range 2.40 to 2.55. Emission from the outer rim of the NPS shows a slightly greater
spectral index than the distributed emission on either side of the feature. The mean local synchrotron emissivity at 22MHz deduced from the emission toward nearby extended opaque HII regions is ~1.5x10^-40^W/m^3^/Hz/sr, somewhat greater than previous estimates.
%K Galaxy: structure - radio continuum: general; ISM

%R 1999A&AS..137...21B
%J-41
%A Bosch G., Terlevich R., Melnick J., Selman F.
%T The ionising cluster of 30 Doradus. II. Spectral classification for 175 stars.
%M h1193
%F 1999.05.18
%B We present spectral types for 175 stars in the ionising cluster of 30 Doradus derived from multislit observations of 231 stars. Comparison with published classifications for 70 stars in common with other authors reveals excellent agreement with the exception of a few cases which are discussed in detail. Our new observations raise to 261 the total number of stars in 30 Dor with known spectral types, outside R136. We analyse the spatial distribution of these stars according
to their spectral types, and find evidence for mass segregation.
%K stars: Hertzsprung Russell (HR) diagram - stars: luminosity function, mass function - stars: early-type - ISM: dust, extinction - galaxy: open clusters and associations: general - galaxies: Magellanic Clouds

%R 1999A&AS..137...43F
%J-49
%A Forster J.R., Caswell J.L.
%T OH and H_2_O masers in 74 star-forming regions. The FC89 database.
%M h1184
%F 1999.05.18
%B Positions and spectra of 1665 MHz OH and 23235 MHz H_2_O masers in 74 star-forming regions are presented. This supplement provides an electronic version of the complete VLA database of interstellar masers observed by Forster & Caswell (1989A&A...213..339F). The fields observed comprise the majority of known interstellar OH and H_2_O maser associations at galactic longitudes observable from both hemispheres. The database will be useful for interpreting continuum and molecular line
observations of these regions, for investigations of the relationship between the masers and their local environment, and for temporal and kinematical studies of the masers themselves.
%K masers - HII regions - stars: pre-main sequence - catalogs

%R 1999A&AS..137...51N
%J-74
%A Nonino M., Bertin E., da Costa L., Deul E., Erben T., Olsen L., Prandoni I., Scodeggio M., Wicenec A., Wichmann R., Benoist C., Freudling W., Guarnieri M.D., Hook I., Hook R., Mendez R., Savaglio S., Silva D., Slijkhuis R.
%T ESO Imaging Survey. I. Description of the survey, data reduction and reliability of the data.
%M ds7652
%F 1999.05.18
%B This paper presents the first data evaluation of the ESO Imaging Survey (EIS), a public survey being carried out by ESO and member states, in preparation for the VLT first-light. The survey goals, organization, strategy and observations are discussed and an overview is given of the survey pipeline developed to handle EIS data and produce object catalogs. A report is presented on moderately deep I-band observations obtained in the first of four patches surveyed, covering a
region of 3.2 square degrees centered at {alpha} ~22^h^40^m^ and {delta}=-40{deg}. The products available to the community, including pixel maps (with astrometric and photometric calibrations) and the corresponding object catalogs, are also described. In order to evaluate the quality of the data, preliminary estimates are presented for the star and galaxy number counts, and for the angular two-point correlation function obtained from the available data. The present work is
meant as a preview of the final release of the EIS data that will become available later this year.
%K surveys - stars: statistics - galaxies: statistics

%R 1999A&AS..137...75Z
%J-81
%A Zaggia S., Hook I., Mendez R., da Costa L., Olsen L.F., Nonino M., Wicenec A., Benoist C., Deul E., Erben T., Guarnieri M.D., Hook R., Prandoni I., Scodeggio M., Slijkhuis R., Wichmann R.
%T ESO Imaging Survey. IV. Multicolor analysis of point-like objects toward the South Galactic Pole.
%M ds7976
%F 1999.05.18
%B This paper presents preliminary lists of potentially interesting point-like sources extracted from multicolor data obtained for a 1.7 square degree region near the South Galactic Pole. The region has been covered by the ESO Imaging Survey (EIS) in B, V and I and offers a unique combination of area and depth. These lists, containing a total of 330 objects nearly all brighter than I~21.5, over 1.27 square degrees (after removing some bad regions), are by-products of the
process of verification and quality control of the object catalogs being produced. Among the color selected targets are candidate very low mass stars/brown dwarfs (54), white-dwarfs (32), and quasars (244). In addition, a probable fast moving asteroid was identified. The objects presented here are natural candidates for follow-up spectroscopic observations and illustrate the usefulness of the EIS data for a broad range of science and for providing possible samples for the
first year of the VLT.
%K surveys - quasars: general - white dwarfs - stars: low-mass

%R 1999A&AS..137...83S
%J-92
%A Scodeggio M., Olsen L.F., da Costa L., Slijkhuis R., Benoist C., Deul E., Erben T., Hook R., Nonino M., Wicenec A., Zaggia S.
%T ESO Imaging Survey. VII. Distant cluster candidates over 12 square degrees.
%M ds8026
%F 1999.05.18
%B In this paper the list of candidate clusters identified from the I-band images of the ESO Imaging Survey (EIS) is completed using the data obtained over a total area of about 12 square degrees (EIS Patches C and D). 248 new cluster candidates are presented. Together with the data reported earlier the total I-band coverage of EIS is 17 square degrees, which has yielded a sample of 302 cluster candidates with estimated redshift in the range 0.2<~z<~1.3 and a median
redshift of z=0.5. This is the largest optically-selected sample currently available in the Southern Hemisphere. It is also well distributed in the sky thus providing targets for a variety of VLT programs nearly year round.
%K galaxies: clusters: general - large-scale structure of the Universe - Cosmology: observations - surveys

%R 1999A&AS..137...93G
%J-99
%A Gutierrez C.M., Garcia Lopez R.J., Rebolo R., Martin E.L., Francois P.
%T Lithium abundances in metal-poor stars. I. New observations.
%M ds1517
%F 1999.05.18
%B We present the lithium measurements of a continuing programme of light element abundances in metal-poor stars. New equivalent widths of the LiI {lambda}670.8 nm resonance line in 67 metal-poor stars covering the metallicity range -3.5<=[Fe/H]<=-0.4 are reported. For about half of this sample, the observations presented here represent the first measurement of the LiI line. The sample allowed a statistical comparison with previous measurements from other authors and a
study of the consistency and reliability of the quoted error bars. This paper shows that for most of the stars these error bars are good estimates of the true uncertainties associated with the determination of the equivalent widths of the LiI line. However, about 20% of the stars with two or more independent measurements show discrepancies in the LiI equivalent widths; in these cases, other sources of uncertainty not properly taken into account (binarity effects, cosmic rays,
imperfect flat-field correction, continuum determination, etc.) could also be important. Conclusions on the possible lithium abundance trends versus effective temperature or metallicity and on any intrinsic scatter should be treated cautiously until their robustness vis-a-vis these additional uncertainties is proved.
%K Galaxy: evolution - stars: abundances - stars: late-type - stars: Population II

%R 1999A&AS..137..101M
%J-112
%A Moriondo G., Baffa C., Casertano S., Chincarini G., Gavazzi G., Giovanardi C., Hunt L.K., Pierini D., Sperandio M., Trinchieri G.
%T Near-infrared observations of galaxies in Pisces-Perseus. I. {vec}(H)-band surface photometry of 174 spirals.
%M h1292
%F 1999.05.18
%B We present near-infrared, H-band (1.65{mu}m), surface photometry of 174 spiral galaxies in the area of the Pisces-Perseus supercluster. The images, acquired with the ARNICA camera mounted on various telescopes, are used to derive radial profiles of surface brightness, ellipticities, and position angles, together with global parameters such as H-band magnitudes and diameters. The mean relation between H-band isophotal diameter D_21.5_ and the B-band D_25_ implies a B-H
color of the outer disk bluer than 3.5; moreover, D_21.5_/D_25_ depends on (global) color and absolute luminosity. The correlations among the various photometric parameters suggest a ratio between isophotal radius D_21.5_/2 and disk scale length of ~3.5 and a mean disk central brightness =~17.5H-mag/arcsec^2^. We confirm the trend of the concentration index C_31_ with absolute luminosity and, to a lesser degree, with morphological type. We also assess the influence of
non-axisymmetric structures on the radial profiles and on the derived parameters.
%K galaxies: fundamental parameters - galaxies: spiral - infrared: galaxies

%R 1999A&AS..137..113V
%J-116
%A van Houten C.J., Walraven T., Walraven J.H.
%T Five-colour photometry of OB-stars in the Southern Hemisphere.
%M h0695
%F 1999.05.18
%B Observations of OB-stars, made in 1959 and 1960 at the Leiden Southern Station near Hartebeespoortdam, South Africa, with the VBLUW photometer attached to the 90 cm light-collector, are given in this paper. They are compared with photometry obtained by Graham (1968BANS....2..397G), Walraven & Walraven (1977BAN....15...67W), Lub & Pel (1977A&A....54..137L) and van Genderen et al. (1984A&AS...58..537V). Formulae for the transformation of the present observations to those of Walraven & Walraven (1977BAN....15...67W) and Lub & Pel
(1977A&A....54..137L) are given.
%K stars, early type - stars, fundamental parameters (colours)

%R 1999A&AS..137..117B
%J-145
%A Breysacher J., Azzopardi M., Testor G.
%T The fourth catalogue of Population I Wolf-Rayet stars in the Large Magellanic Cloud.
%M ds1668
%F 1999.05.18
%B The catalogue provides for each of the 134 W-R stars of Population I presently known in the Large Magellanic Cloud, accurate equatorial coordinates, photometric data, spectral classification, binary status, correlation with OB associations and HII regions. The miscellaneous designations of the stars are also listed. Although completeness is not pretended, results published during the last decade are highlighted in the notes given for each individual star. A uniform set of
finding charts is presented.
%K Catalogs - galaxies: Magellanic Clouds - galaxies: stellar content - stars: Wolf-Rayet

%R 1999A&AS..137..147S
%J-156
%A Steele I.A., Negueruela I., Clark J.S.
%T A representative sample of Be stars. I. Sample selection, spectral classification and rotational velocities.
%M h1180
%F 1999.05.18
%B We present a sample of 58 Be stars containing objects of spectral types O9 to B8.5 and luminosity classes III to V. We have obtained 3670-5070{AA} spectra of the sample which are used to derive spectral types and rotational velocities. We discuss the distribution of spectral types and rotational velocities obtained and conclude that there are no significant selection effects in our sample.
%K stars: emission-line, Be - stars: fundamental parameters - stars: rotation

%R 1999A&AS..137..157K
%J-163
%A Kisielius R., Storey P.J.
%T Recombination coefficients for the 5g - 4f transitions of OIII at nebular temperatures and densities.
%M ds8521
%F 1999.05.18
%B We calculate effective recombination coefficients for the formation of the 5g - 4f lines of OIII in the intermediate coupling scheme. Photoionization data for the 5g levels calculated using the R-matrix method are used to derive their recombination coefficients. Cascading from higher states is included, allowing for the effects of finite electron density in a hydrogenic approximation. We explicitly include the distribution of population between the two ground levels of
O^3+^ in the calculation of the line intensities. The results are presented as a simple programmeable formula allowing the calculation of recombination line intensities for electron temperatures, T_e_ in the range 5000-20000K and electron densities, N_e_ in the range 10^2^-10^6^cm^-3^.
%K atomic data - atomic processes - line: formation - ISM: H II regions - ISM: planetary nebulae: general

%R 1999A&AS..137..165E
%J-173
%A Eissner W., Galavis M.E., Mendoza C., Zeippen C.J.
%T Atomic data from the IRON Project. XXXVIII. Electron impact excitation of the fine-structure transitions in the n=3 complex of Fe XV.
%M ds1666
%F 1999.05.18
%B As part of a systematic study of the collisional properties of Fe ions carried out by the IRON Project, electron excitation rates (effective collision strengths) are computed for all the fine-structure transitions within the n=3 complex of Fe XV in the electron temperature range 10^5^<=T/K<=10^7^. Configuration-interaction target wavefunctions are generated with the atomic structure code superstructure, and collision strengths are computed in the close-coupling
approximation with a Breit-Pauli R-matrix package. Special care is taken to resolve the resonance structure and to ensure the convergence of the partial wave expansion, specially for dipole allowed transitions. By comparing with previously calculated collision strengths in the distorted wave approximation, a 20% accuracy rating is assigned to transitions with effective collision strengths {Upsilon}(T)>10^-2^.
%K atomic data - Sun: corona

%R 1999A&AS..137..175C
%J-184
%A Chidichimo M.C., Zeman V., Tully J.A., Berrington K.A.
%T Atomic data from the IRON Project. XXXVI. Electron excitation of Be-like Fe XXIII between 1s^2^2l_1_2l_2_SLJ and 1s^2^2l_3_2l_4_S'L'J'.
%M ds1638
%F 1999.05.18
%B Partial collision strengths for electron induced transitions in the beryllium-like ion Fe XXIII are calculated using the Belfast R-matrix programs (Berrington et al., 1995, Comput. Phys. Commun. 92, 290). Our target has 98 fine structure states 1s^2^nln'l'SLJ corresponding to n=2 and n'=2, 3, 4 . The present calculation is carried out for electron impact energies in the range 3.15 to 350Ry. Below 115.185Ry, corresponding to the highest excited state of our model ion, we use the Breit-Pauli version of
the R-matrix code. For energies between 116 and 350Ry we use the non-relativistic LS-coupling version of the R-matrix code together with JAJOM (Saraph, 1978, Comput. Phys. Commun. 15, 247). When T exceeds about ten million degrees one needs to take account of contributions to the thermally averaged collision strength {Upsilon} coming from electrons with energies in excess of 350Ry. We discuss a way of estimating these contributions. Values of {Upsilon} are computed and tabulated as functions of logT for
transitions between the 2s^2^ ^1^S_0_, 2s2p^3^P_0,1,2_^o^, 2s2p^1^P_1_^o^, 2p^2^^3^P_0,1,2_, 2p^2^ ^1^D_2_ and 2p^2^ ^1^S_0_ states. The temperature range 6.3<=logT<=8.1 is centred on logT=7.1 which, according to Arnaud & Rothenflug (1985A&AS...60..425A), is where Fe XXIII has maximum coronal abundance.
%K atomic data - Sun: corona

%R 1999A&AS..137..185M
%J-202
%A Masciadri E., Vernin J., Bougeault P.
%T 3D mapping of optical turbulence using an atmospheric. numerical model I. A useful tool for the ground-based astronomy.
%M ds7850
%F 1999.05.18
%B These last years have seen the development of many devices to measure and monitor some atmospheric parameters characterizing the image degradation at the telescope focus. Many uncertainties about the possibility to forecast such parameters are real although this skill is fundamental for site testing, flexible scheduling and optimization of the performance of both interferometry and adaptive optics. We present our atmospheric numerical model, conceived to provide 3D maps of
the classic meteorological parameters P, T and {vec}(V), and also 3D maps of the C_N_^2^ optical turbulent profiles. Knowing the wind {vec}(V) and the C_N_^2^ profiles, the following integrated parameters are coded: seeing {epsilon}, coherence wavefront time {tau}_AO_, isoplanatic angle {theta}_AO_, scintillation rate {sigma}^2^_I_ and spatial coherence outer scale L_0_ . The ability of the model to produce a 3D map of optical turbulence in the vicinity of a telescope and
the effects of horizontal grid size are discussed. We demonstrate, for the same night, the global coherence of the different simulation outputs. Here we consider the use that this model could have in ground-based astronomy and we describe how it could be used to give a real forecast of the optical turbulence.
%K atmospheric effects, turbulence, site testing

%R 1999A&AS..137..203M
%J-216
%A Masciadri E., Vernin J., Bougeault P.
%T 3D mapping of optical turbulence using an atmospheric numerical model II. First results at Cerro Paranal.
%M ds7968
%F 1999.05.18
%B The first statistical results of simulations of optical turbulence over Cerro Paranal by an atmospheric non-hydrostatic model (Meso-Nh) are presented. Measurements from the whole PARSCA93 campaign are analyzed. Simulations are compared to optical measurements obtained by a Scidar and a DIMM working at the same time during 14 nights 13-26 May 1993 over Paranal (Chile). An orographic model with a horizontal resolution of 500m is implemented in Meso-Nh to study its
sensitivity to the orographic effects. The model is initialized with radiosoundings profiles provided by Antofagasta station (70.43 W, 23.43 S) and ECMWF analyses extracted from the nearest grid point (70.31 W, 23.62 S) to this meteorological station. A detailed quality study of radiosounding and analyses is presented. No radiosoundings were provided by Antofagasta station during 4 nights and numerical instabilies were generated by the model during the 13 and 26 May 1993
nights. So, only 8 nights were actually studied. Two statistical methods are presented: Method A has a high temporal resolution, Method B has a high vertical spatial resolution. Method A compares integrated values (seeing) provided by simulations and measurements, Method B compares the C_N_^2^ profiles. Different statistical estimators are computed for both the methods. We demonstrate that the model can reproduce well the spatial distribution of the optical turbulence in both
the high and low atmospheric regions but the unreliability of Antofagasta radiosoundings hampers the statistical results of the numerical technique. To better test the performance of the model, a comparison between the numerical and the forecasting-by-persistence techniques is presented. With a poor statistical sample (only 8 nights), no conclusive statements can be made about the performances of the two techniques. The model ability to discriminate between the best
({epsilon}=0.38) and the worst ({epsilon}=1.38) nights of the campaign is promising for the future implementation of the numerical technique for flexible scheduling of telescopes.
%K atmospheric effects - site testing - turbulence