%R 1998A&AS..130..403H
%J-406
%A Heck A.
%T Geographical distribution of observational activities for astronomy.
%M ds7270
%F 1998.06.12
%B The geographical distribution of astronomy-related observational activities is illustrated from comprehensive and up-to-date samples of professional institutions, of public observatories and planetariums, and of associations. Results are commented and, in particular, the lack of evolution over the past century in the overall distribution is pointed at as an alarming indicator.
%K sociology of astronomy - astronomical databases: miscellaneous

%R 1998A&AS..130..407R
%J-414
%A Royer P., Vreux J.-M., Manfroid J.
%T A dedicated photometric system for the classification of Wolf-Rayet stars.
%M ds7214
%F 1998.06.12
%B We present here tests of a five-filter photometric system aimed at WR classification. In addition to the well-known easy separation between the WN and WC spectral types, these tests indicate interesting potentialities in the discrimination of subgroups among the WN and the WC which look well related to the classical subtypes. The proposed combinations of filters (or derived ones) bear enough discriminating power to satisfy some evolutionary studies in crowded fields where
spectroscopic follow-up is not possible.
%K stars: Wolf-Rayet - techniques: photometry

%R 1998A&AS..130..415G
%J-419
%A Ginestet N., Carquillat J.-M.
%T Contribution a l'etude de la binarite des etoiles de type Am. I. HD 125273, binaire spectroscopique a raies doubles (HD 125273, a double-lined spectroscopic binary).
%M ds6302
%F 1998.06.12
%B We present an observing program undertaken at Observatoire de Haute-Provence, for the search and study of spectroscopic binaries among Am stars. HD 125273 was recognized as an Am star some time ago (Olsen, 1980A&AS...39..205O, Abt, 1984pJ...285..247A) observations, carried out with the CORAVEL spectrovelocimeter, show that this star is a double-lined spectroscopic binary; its orbital elements are as follows: P=7.482664days; T=2448665.660JD; {omega}_1_=355.3{deg}; e=0.071; 
K_1_=49.82km/s; K_2_=51.75km/s; V_0_=-17.42km/s; a_1_sini=5.113Gm; a_2_sini=5.311Gm; M_1_sin^3^i=0.412M_{sun}_; M_2_sin^3^i=0.396M_{sun}_.
Stroemgren photometry of the star (Olsen, 1983A&AS...54...55O) permits us to estimate the following mean physical parameters for the components of the binary: T_eff_=7500K; logg=3.70; M_v_=1.24; M=2.1M_{sun}_; R=3.2R_{sun}_, and to specify the evolutionary status of the system. Assuming the above mass for the components, we found i~35{deg} and a ~26R_{sun}_. This system is thus a detached one without possibility of eclipses. It is likely that the two components are Am stars
of very close characteristics. The vsini values, determined from the correlation dips given by CORAVEL, are near 11km/s for both components. We retain for this binary the hypothesis of rotation-revolution synchronism, because it leads to a value of the radius of the stars in agreement both with the above value and the results of a previous study by Kitamura & Kondo (1978Ap&SS..56..341K) of similar, but eclipsing, systems. The ratio of the correlation dip areas indicates a magnitude
difference {DELTA}m_v_~0.2mag. As expected in detached systems of main sequence stars, such as Am's, HD 125273 obeys the mass-luminosity law. 
%K stars: individual: HD 125273; binaries: spectroscopic - stars: fundamental parameters 

%R 1998A&AS..130..421F
%J-440
%A Filipovic M.D., Haynes R.F., White G.L., Jones P.A.
%T A radio continuum study of the Magellanic Clouds. VII. Discrete radio sources in the Magellanic Clouds.
%M ds1486
%F 1998.06.12
%B We present a study of discrete radio sources in the Magellanic Clouds (MCs) using the latest large-scale radio surveys made with the Parkes radio telescope between 1.4 and 8.55GHz. These surveys achieved higher sensitivity then previous surveys done with the Parkes telescope and so the number of discrete radio sources detected towards the MCs has increased by factor of five. Also, we have obtained improved positions, flux densities and radio spectral indices for all of
these sources. A total of 483 sources towards the Large Magellanic Cloud (LMC) and 224 towards the Small Magellanic Cloud (SMC) have been detected at at least one radio frequency. Most of the MC's sources have been classified in one of three groups: SNRs, HII regions or background sources according to classification criteria established here. In total, 209 discrete radio sources in the LMC and the 37 sources in the SMC are classified here to be either HII regions or SNRs. We
investigate their luminosity functions as well as the statistics of background sources behind the MCs. Also, we examine the distribution of SNRs and HII regions in the MCs.
%K galaxies: Magellanic Clouds - radio continuum: galaxies - ISM: HII regions - ISM: supernova remnants (SNRs) - galaxies: ISM

%R 1998A&AS..130..441F
%J-448
%A Filipovic M.D., Jones P.A., White G.L., Haynes R.F.
%T A radio continuum study of the Magellanic Clouds. VIII. Discrete sources common to radio and infrared surveys of the Magellanic Clouds.
%M ds1488
%F 1998.06.12
%B We compare Parkes Telescope radio surveys with the IRAS Infrared (IR) surveys of the Magellanic Clouds (MCs). We find 130 discrete sources in common towards the Large Magellanic Cloud (LMC) with both radio and IR emission. These 130 sources are mainly HII regions (89) and supernova remnants (21). For 12 of the sources we have no identification and eight are background objects. We find 38 sources in common for the Small Magellanic Cloud (SMC). Most of these sources are
intrinsic (31) to the SMC, five sources are previously known background galaxies and two sources remain ambiguous. A flux density comparison of the radio and IR sources shows very good correlation and we note that the strongest sources at both radio and IR frequencies are HII regions. From the radio-IR comparison we propose that some 40 new sources in the LMC and 10 in the SMC are HII regions or SNRs. All these new sources are also identified in optical surveys.
%K galaxies: Magellanic Clouds - radio continuum: galaxies - infrared: galaxies - ISM: HII regions - ISM: supernova remnants (SNRs) - galaxies: ISM

%R 1998A&AS..130..449M
%J-454
%A Ma J., Peng Q.-H., Gu Q.-S.
%T The thicknesses and inclinations of 71 northern spiral galaxies.
%M ds7136
%F 1998.06.12
%B This paper presents the thicknesses and inclinations (i.e., the angle between the galactic plane and the tangent plane) of 71 northern spiral galaxies. The method for measuring the thickness has been proposed by Peng. It is based on the solution of Poisson's equation for a logarithmic disturbance of density. The inclination is determined by assuming that the pattern of spiral structure is a logarithmic spiral. We find that the thickness is correlated with color and with
the H_{alpha}_+[NII] equivalent width.
%K galaxies: spiral; structure; kinematics and dynamics; fundamental parameters

%R 1998A&AS..130..455V
%J-464
%A Vogt N., Kerschbaum F., Maitzen H.M., Faundez-Abans M.
%T An extensive {DELTA}a-photometric survey of southern B and A type bright stars.
%M ds6689
%F 1998.06.12
%B Photoelectric photometry of 803 southern BS objects in the {DELTA} a-system as detection tool for magnetic chemically peculiar (=CP2) stars has been carried out and compared to published spectral types. The statistical yield of such objects detected by both techniques is practically the same. We show that there are several factors which contaminate the search for these stars, but this contamination is only of the order of 10% in both techniques. We find a smooth transition
from normal to peculiar stars. Our sample exhibits the largest fraction of CP2 stars at their bluest colour interval, i.e. 10% of all stars in the colour range -0.19<=B-V<-0.10 or -0.10<=b-y<-0.05. No peculiar stars based on the {DELTA}a-criterion were found at bluer colours. Towards the red side the fraction of CP2 stars drops to about 3% for positive values of B-V or b-y with red limits roughly corresponding to normal stars of spectral type A5. The photometric
behaviour of other peculiar stars: Am, HgMn, {delta} Del, {lambda} Boo, He abnormal stars, as well as Be/shell stars and supergiants shows some slight, but definite deviations from normal stars. Spectroscopic and visual binaries are not distinguished from normal stars in their {DELTA}a behaviour. The results of this work justify larger statistical work (e.g. in open clusters) employing more time-saving photometric methods (CCD).
%K techniques: photometric - stars: chemically peculiar - catalogues

%R 1998A&AS..130..465P
%J-476
%A Phillips J.P., Guzman V.
%T Spectral trends in planetary nebulae: The roles of radiative and shock excitation.
%M ds1473
%F 1998.06.12
%B We have investigated de-reddened spectral line ratios for some 538 planetary nebulae. As a result, it has proved possible to define comparative variations between differing transitions, evaluate the viability of radiative modeling for the generality of nebulae, and assess the importance of shocks in modifying low- excitation line strengths. Whilst most transitions are well represented in terms of radiative excitation, the [OI] {lambda}6300{AA} line appears to be
appreciably too strong in most of the present sample; a deviation which may arise through shock interaction between the primary outflow shell and enveloping superwind material. Comparison between shock modeling and line excesses also suggests that an appreciable proportion of [SII] {lambda}6716/31{AA} emission may arise through shock excitation; a conclusion which, if confirmed, may have serious consequences for nebular density estimations. Some 14 nebulae are identified as
likely shock candidates, whilst it is proposed that the majority of bipolar nebulae may also show spectral deviations associated with shock excitation. Line excesses for these latter sources are most consistent with shock velocities V_s_~80-100km/s; values which are also comparable to observed wind velocities. Finally, sources containing FLIERs (Balick et al., 1993ApJ...411..778B) are shown to be confined to highly specific spectral regimes; a result which permits us to identify
three further possible FLIER sources, and propose characteristic line ratio diagnostics for the further discovery of such features.
%K survey - ISM: planetary nebulae - ISM: jets and outflows - shocks waves

%R 1998A&AS..130..477K
%J-484
%A Knude J.
%T Stellar uvby{beta} photometry in three EUV shadow directions.
%M ds1481
%F 1998.06.12
%B We present the uvby{beta} data used to locate the dust and derive distances for nearby diffuse interstellar clouds in the EUV shadows lb27-31, lb165-32 and lb329+46 discovered by the Extreme Ultraviolet Explorer. The photometrically derived parallaxes of our program stars are compared to the parallaxes listed in the Hipparcos Catalog. Within the photometric distance limit of 150pc, the photometric parallaxes of 21 ``normal" stars are consistent with the Hipparcos
measurements within an uncertainty of 15%. Much as expected for the Stroemgren system. Since all program stars are brighter than V=~11.5 most of them are included in the Tycho photometry. For our sample of ~200 stars we find V_by_ and V_T_ to be consistent. Few stars are common to published uvby{beta} catalogs, ~10, V and the indices compare well apart from {beta} where a zero point difference of 11mmag is noticed.
%K stars: distances - solar neighbourhood - ISM: clouds

%R 1998A&AS..130..485S
%J-494
%A Spogli C., Fiorucci M., Tosti G.
%T BVRI observations of dwarf novae in outburst. I. AL Comae Berenices, V544 Herculis, V660 Herculis, V516 Cygni and DX Andromedae.
%M ds1375
%F 1998.06.12
%B In this paper we report photometric observations of AL Com, V544 Her, V660 Her, V516 Cyg and DX And taken during the descending phase after an outburst. For four of these variables we calibrated comparison stars in the field of view. Our observations cover the period in which AL Com showed the larger optical outburst since 1974, and V660 Her showed the larger outburst ever reported in the literature (B=~14.3). The optical spectral distribution of DX And, AL Com and V660
Her shows that the model of the steady-state accretion disk does not provide a good representation of the optical continuum during the decline phase of a dwarf nova outburst.
%K stars: cataclysmic variables; stars: individual: AL Com, V544 Her, V660 Her, V516 Cyg, DX And

%R 1998A&AS..130..495R
%J-500
%A Raiteri C.M., Villata M., Lanteri L., Cavallone M., Sobrito G.
%T BVR photometry of comparison stars in selected blazar fields. II. Photometric sequences for 9 quasars.
%M ds1501
%F 1998.06.12
%B In the course of the blazar monitoring activity at the Torino Astronomical Observatory, we obtained standard BVR magnitudes for 36 stars and standard VR magnitudes for 10 stars in the fields of 9 quasars. Observations were done during 14 photometric nights with the 1.05 m Cassegrain REOSC telescope equipped with a 1242 x 1152 pixel CCD camera. All stars are brighter than V=16.6 and are useful comparison objects for the evaluation of the quasar magnitudes.
%K galaxies: active - quasars: general

%R 1998A&AS..130..501K
%J-506
%A Kerber F., Roth M., Manchado A., Groebner H.
%T New evolved planetary nebulae in the southern hemisphere.
%M ds1471
%F 1998.06.12
%B The major purpose of this paper is to investigate the nature of planetary nebulae (PNe) candidates in the southern hemisphere, taken from an internal list. We present spectroscopic observations and imaging of six PNe identified for the first time. Another candidate turned out to be a galaxy. All observed PNe represent evolved stages, their angular diameter ranging from 15" to 120", and exhibit very low surface brightnesses. For three PNe indications of interaction with the
interstellar medium (ISM) has been discovered.
%K surveys - planetary nebulae: general

%R 1998A&AS..130..507J
%J-512
%A Jaschek C., Andrillat Y.
%T Ae and A type shell stars.
%M ds7261
%F 1998.06.12
%B We present and discuss the observations of 14 Ae and A type shell stars in the visual, the H{alpha} region and the near infrared. At least 57% of these stars are spectrum variables. The Paschen lines are formed in a region which has the characterics of giant stars. We find that the systems lie one magnitude above the main sequence and that a large percentage belong to double and triple systems.
%K stars: early type; emission line; variables

%R 1998A&AS..130..513G
%J-526
%A Garcia-Vargas M.L., Molla M., Bressan A.
%T Calcium triplet synthesis.
%M ds1379
%F 1998.06.12
%B We present theoretical equivalent widths for the sum of the two strongest lines of the calcium triplet, CaT index, in the near-IR ({lambda}{lambda} 8542, 8662{AA}), using evolutionary synthesis techniques and the most recent models and observational data for this feature in individual stars. We compute the CaT index for Single Stellar Populations (instantaneous burst, standard Salpeter-type IMF) at four different metallicities, Z=0.004, 0.008, 0.02 (solar) and 0.05, and
ranging in age from very young bursts of star formation (few Myr) to old stellar populations, up to 17Gyr, representative of galactic globular clusters, elliptical galaxies and bulges of spirals. The interpretation of the observed equivalent widths of CaT in different stellar systems is discussed. Composite-population models are also computed as a tool to interpret the CaT detections in star-forming regions, in order to disentangle between the component due to Red Supergiant
stars, RSG, and the underlying, older, population. CaT is found to be an excellent metallicity-indicator for populations older than 1 Gyr, practically independent of the age. We discuss its application to remove the age-metallicity degeneracy, characteristic of all studies of galaxy evolution based on the usual integrated indices (both broad band colors and narrow band indices). The application of the models computed here to the analysis of a sample of elliptical galaxies
will be discussed in a forthcoming paper Gorgas et al. 1997).
%K galaxies: stellar content; starbursts; elliptical

%R 1998A&AS..130..527T
%J-538
%A Testor G., Niemela V.
%T The OB associations LH 101 and LH 104 in the HII region N158 of the LMC.
%M h0759
%F 1998.06.12
%B We present photometric and spectroscopic observations of stars in the Large Magellanic Cloud OB associations LH 101 and LH 104, located in the HII region N158, which we have also imaged. From our observations we have constructed upper H-R diagrams for these OB associations, which we find to consist mainly of three populations, one of 2-6Myr for the stars inside the northern bubble (LH 104), and two populations in the southern HII region (LH 101), one of <=2Myr and the
other one aged 3-6Myr. We have obtained for LH 101 a normal IMF, with a slope of {GAMMA}=-1.29+/-0.20 whereas for LH 104 the IMF is flatter with a slope of {GAMMA}=-1.05+/-0.12. These IMF slopes are consistent with that of other OB associations in the LMC. Our observations reveal in the region of LH 101 the presence of both unevolved and evolved very massive stars, whose ionizing flux is in excess of that derived from our H{beta} images of the HII region. The
north-west nebulosity in the region of LH 101 thus appears to be matter bound.
%K Magellanic Clouds - open clusters and associations: individual: \objS{LH 101}{LMC-LH 101}, \object{LH 104} - stars: early type - stars: Wolf-Rayet

%R 1998A&AS..130..539D
%J-540
%A Dimitrijevic M.S., Sahal-Brechot S.
%T Stark broadening of spectral lines of multicharged ions of astrophysical interest. XIX. Na X spectral lines.
%M ds1497
%F 1998.06.12
%B Using a semiclassical perturbation approach, we have calculated electron-, proton-, and He III-impact line widths and shifts for 57 Na X multiplets for perturber densities 10^17^-10^24^cm^-3^ and temperatures T=200000-5000000K. For lower perturber densities, the Stark broadening parameters are proportional to the perturber density.
%K lines: profile - atomic data

%R 1998A&AS..130..541R
%J-549
%A Raassen A.J.J., Pickering J.C., Uylings P.H.M.
%T Calculated oscillator strengths of singly ionized cobalt.
%M ds7226
%F 1998.06.12
%B Transition probabilities of the spectrum of Co II are calculated using the orthogonal operator description for both the odd and the even energy levels.
%K atomic data - ISM: abundances - stars: chemically peculiar - supernovae

%R 1998A&AS..130..551B
%J-560
%A Burigana C., Maino D., Mandolesi N., Pierpaoli E., Bersanelli M., Danese L., Attolini M.R.
%T Beam distortion effects on anisotropy measurements of the cosmic microwave background.
%M ds7256
%F 1998.06.12
%B High resolution observations of CMB anisotropy requires the use of feed arrays at the focus of an optical system. Beam responses are typically not symmetric for array elements de-centred from the telescope focus, whereas theoretical predictions and standard deconvolution methods generally assume pure symmetric beams. For estimating the effect of main beam asymmetry on temperature fluctuations measurements we have generated high resolution sky maps by using standard
spherical harmonics expansion for the CMB fluctuations and by extrapolating available full sky maps to predict Galaxy emission at frequencies and angular scales appropriate to future space missions, like Planck and MAP. We have then convolved simulated maps of the microwave sky with asymmetric beams by adopting the Planck configuration and scanning strategy. We find that the typical difference between temperature measurements performed by symmetric and asymmetric beams is of
few {mu}K and that it is an increasing function of the beam eccentricity and FWHM. Although this effect is not very large, it is of order of the ultimate sensitivity of the next generation of experiments, and must be reduced by optimizing the feedhorns locations on the focal plane.
%K cosmology: cosmic microwave background - diffuse radiation - methods: data analysis - telescopes

%R 1998A&AS..130..561G
%J-566
%A Ghedina A., Ragazzoni R., Baruffolo A.
%T Isokinetic patch measurements on the edge of the Moon.
%M ds1440
%F 1998.06.12
%B By imaging the edge of the Moon we have tested a seeing monitor able to evaluate the isokinetic patch size. These measurements have a relevant interest because of several Laser Guide Star (LGS) tilt recovery schemes that have been proposed. In our approach the edge of the Moon mimics a LGS as seen far from the laser projector. The conceptual design of the instrument, the data reduction techniques and the preliminary results obtained at the Asiago Astronomical Observatory
are given. Because, as a by product, the instrument is able to evaluate r_0_, a comparison with seeing data collected at the 1.82 m telescope of Cima Ekar during the three nights test of the described instrument is also given.
%K Moon - instrumentation: adaptive optics

%R 1998A&AS..130..567K
%J-579
%A Kawasaki W., Shimasaku K., Doi M., Okamura S.
%T An objective and automatic cluster finder: An improvement of the matched-filter method.
%M ds6487
%F 1998.06.12
%B We describe an objective and automated method for detecting clusters of galaxies from optical imaging data. This method is a variant of the so-called ``matched-filter'' technique pioneered by Postman et al. (1996AJ....111..615P). Simultaneously using positions and apparent magnitudes of galaxies, this method can, not only find cluster candidates, but also estimate their redshifts and richnesses as byproducts of detection. We examine errors in the estimation of cluster's position,
redshift, and richness with a number of Monte Carlo simulations. No systematic discrepancies between the true and estimated values are seen for either redshift or richness. For clusters with z=0.2 and with richness similar to that of the Coma cluster, typical errors in the estimation of position, redshift, and richness are evaluated as {DELTA}{theta}~10'' (one third of the projected core radius), {DELTA}z~0.02, and {DELTA}N/N~12%, respectively. Spurious detection rate of the
method is about less than 10% of those of conventional ones which use only surface density of galaxies. A cluster survey in the North Galactic Pole region is executed to verify the performance characteristics of the method with real data. Despite poor quality of the data, two known real clusters are successfully detected. No unknown cluster with low or medium redshift (z<=0.3) is detected. We expect these methods based on ``matched-filter'' technique to be essential tools
for compiling large and homogeneous optically-selected cluster catalogs.
%K methods: data analysis - galaxies: clustering - galaxies: clusters: individual: \object{A 1677}, \objS{2E 1305.4+2941}{1305.4+2941}