%R 1997A&AS..125....1K
%J-9
%A Kravtsov V., Ipatov A., Samus N., Smirnov O., Alcaino G., Liller W., Alvarado F.
%T NTT CCD photometry of the globular cluster M 79 = NGC 1904 in UBV.
%M ds5540
%F 1997.09.20
%B We have obtained new CCD photometry (with short exposures) of the Milky Way globular cluster M 79 using the NTT under excellent seeing. The main-sequence turnoff point is at V=19.70+/-0.05, B-V=0.415+/-0.010; the horizontal-branch level at the blue edge of the instability strip is V=16.25+/-0.10. The cluster metallicity, estimated from the positions of the "bump" on the red giant branch, is [Fe/H] =-1.76+/-0.20. We discuss the luminosity functions of the horizontal branch
and the asymptotic giant branch, in particular, the fragmentary structure of the horizontal branch in M 79 and in other clusters. Our isochrone analysis shows that M 79 belongs to the oldest Milky Way globular clusters. Its age, in the scale of Bergbusch & VandenBerg (1992ApJS...81..163B) oxygen-enhanced isochrones, is 16+/-1Gyr, and in the scale of VandenBerg & Bell (1985ApJS...58..561V) isochrones it is 18+/-1Gyr. The cluster has an extremely blue horizontal branch at intermediate metallicity and may
be considered a good example of the "second parameter" interpreted as age. The apparent distance modulus of the cluster from Bergbusch and VandenBerg isochrones is in good agreement with the value derived from the position of the horizontal branch (15.6mag).
%K globular clusters: individual: M 79 - HR diagram

%R 1997A&AS..125...11S
%J-63
%A Strassmeier K.G., Bartus J., Cutispoto G., Rodono M.
%T Starspot photometry with robotic telescopes. Continuous UBV and V(RI)_C_ photometry of 23 stars in 1991-1996.
%M ds1287
%F 1997.09.20
%B We report on the progress of our ongoing photometric monitoring program of spotted late-type stars with automatic photoelectric telescopes (APTs) on Mt. Hopkins in Arizona and on Mt. Etna in Sicily. We present 9250 differential UBV and/or V(RI)_C_ observations for altogether 23 chromospherically active stars, singles and binaries, pre main sequence and post main sequence, taken between 1991 and 1996. The variability mechanism of our target stars is mostly rotational
modulation by an asymmetrically spotted stellar surface. Therefore, precise rotational periods and their seasonal variations are determined using baselines between 3 years for HD 129333 to 34 years for V410 Tauri. We report the largest V light-curve amplitude of any spotted star observed to date: 0.65mag for V410 Tau in 1994-95. Long-term variations of the overall light levels of our target stars are sometimes of similar amplitude as the rotational modulation itself and are
most likely caused by an analog of the solar 11-year spot cycle but mostly without a well-defined periodicity. For some of our target stars (HD 12545, HD 17433, EI Eri, V410 Tau, LQ Hya, and HD 106225) we estimate a probable cycle period. A complete light curve of the semi-regular S-type giant HR Pegasii is presented. All data are available via the WorldWideWeb.
%K stars: activity - stars: late-type - stars: rotation - binaries: spectroscopic - techniques: photometric

%R 1997A&AS..125...65A
%J-70
%A Adelman S.J.
%T uvby photometry of the magnetic chemically peculiar stars HD 37776, HR 2258, HR 6958, and 108 Aquarii.
%M ds1305
%F 1997.09.20
%B Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope are presented for four magnetic chemically peculiar stars. Comparison with uvby photometry of Pedersen & Thomsen for HD 37776 yields an improved period of 1.538675 days. New periods of 15.0305 days and 18.065 days are found for the sharp-lined stars HR 2258 and HR 6958, respectively, rather than one of their aliases. For HR 6958 each color shows a slightly
different time of maximum. Comparison of the four color photometry of 108 Aqr taken during the fall of 1995 which well covers the period shows the presence of a secondary minimum near primary maximum in u, v, and b. Comparison with published photometry indicates indicates that subtle changes in the shapes of the light curves have occurred suggesting that this star might be precessing.
%K stars: individual: \object{HD 37766} - stars: individual: \object{HR 2258} - stars: individual: \object{HR 6958} - stars: individual: 108 Aqr (\object{HR 9031}) - stars: chemically peculiar - stars: variable

%R 1997A&AS..125...71C
%J-73
%A Cunow B., Duemmler R., Spiekermann G., Ungruhe R., Wargau W.F.
%T Photometric CCD sequences for calibration of the ESO/SERC atlas.
%M ds1306
%F 1997.09.20
%B For calibration of ESO/SERC survey plates, photometric CCD sequences have been obtained for 10 ESO/SERC fields in the area 10h00<R.A.<15h30 and -34{deg}<Decl.<-18{deg}. The sequences contain B, V and R magnitudes for 117 galaxies and 162 stars with 12.7<V<21.0.
%K techniques: photometric - galaxies: photometry - atlas

%R 1997A&AS..125...75P
%J-98
%A Pavlovski K., Harmanec P., Bozic H., Koubsky P., Hadrava P., Kriz S., Ruzic Z., Stefl S.
%T UBV photometry of Be stars at Hvar: 1972-1990.
%M ds1262
%F 1997.09.20
%B A summary of results of the systematic UBV photoelectric monitoring of bright northern Be stars carried out at the Hvar Observatory between 1972 and 1990 is presented. Altogether, 76 Be stars of all luminosity classes were observed and 13848 UBV measurements secured. Simultaneously, 9648 UBV measurements of 48 check stars (most of them of early spectral types) were obtained. A careful transformation of all observations into the standard Johnson system allowed detection and
monitoring of even very mild long-term light and colour variations of these objects. Almost all early-type Be stars in the sample turned out to be variable. For several stars phase-locked light variations related to their binary nature were established. Sudden brightenings, on a time scale of a few days, were detected for o Cas and QR Vul.
%K stars: Be - stars: individual: Omicron Cas, QR Vul - stars: variable

%R 1997A&AS..125...99B
%J-138
%A Bitran M., Alvarez H., Bronfman L., May J., Thaddeus P.
%T A large scale CO survey of the Galactic center region.
%M ds1300
%F 1997.09.20
%B We present the data from a CO(J=1->0) survey of the central region of our Galaxy. The observations were obtained with the 1.2-m Southern Millimeter-wave Telescope at Cerro Tololo Interamerican Observatory, Chile. This instrument has a full beam-width at half maximum (FWHM) of 8.8' at 115GHz, the frequency of the observed transition. The survey covers a strip 4{deg} wide in latitude along the galactic equator in the range -12{deg}<=l<=+13{deg}. The spatial sampling
interval was 7.5' (0.85 beam-widths) for |b|<=1{deg}, and 15' (1.7 beam-widths) for 1{deg}<|b|<=2{deg}. The velocity coverage allowed by the filterbank was of 333km/s with a resolution of 1.3km/s at 115GHz. For the central few degrees (-4.5{deg}<l<=5{deg}) where this velocity span was not wide enough, two spectra, taken with different velocities with respect to the local standard of rest (VLSR), were combined in order to cover the full range of the galactic
center CO emission. The antenna temperature noise level of the spectra was <=0.10K (rms). The data are presented in a latitude-longitude spatial map and in sets of longitude-velocity and latitude-velocity diagrams. This survey combines the characteristics of being very sensitive and well sampled, and of having one of the widest and more homogeneous spatial coverage of the region within ~2kpc from the galactic center.
%K surveys - ISM: molecules - Galaxy: center - radio lines: ISM

%R 1997A&AS..125..139A
%J-148
%A Aristidi E., Carbillet M., Lyon J.-F., Aime C.
%T Imaging binary stars by the cross-correlation technique.
%M ds6040
%F 1997.09.20
%B We present in this paper a technique for imaging binary stars from speckle data. This technique is based upon the computation of the cross-correlation between the speckle frames and their square. This may be considered as a simple, easy to implement, complementary computation to the autocorrelation function of Labeyrie's technique for a rapid determination of the position angle of binary systems. Angular separation, absolute position angle and relative photometry of binary
stars can be derived from this technique. We show an application to the bright double star {zeta} Sge observed at the 2m Telescope Bernard Lyot.
%K methods: data analysis - techniques: image processing - techniques: interferometric - binaries: close - stars: imaging - stars: individual: {zeta} Sge

%R 1997A&AS..125..149D
%J-173
%A Dere K.P., Landi E., Mason H.E., Monsignori Fossi B.C., Young P.R.
%T CHIANTI - an atomic database for emission lines. I. Wavelengths greater than 50{AA}.
%M ds1260
%F 1997.09.20
%B A comprehensive set of accurate atomic data is required for analyses of astrophysical and solar spectra. CHIANTI provides a database of atomic energy levels, wavelengths, radiative data and electron excitation data for ions which are abundant in cosmic plasmas. The most recent electron excitation data have been assessed and stored following the method of Burgess & Tully (1992A&A...254..436B). The current version is essentially complete for specifying the emission spectrum at
wavelengths greater than 50{AA}. A list of observed lines in the spectral region between 50 and 1100{AA} has been compiled and compared with the lines predicted by the CHIANTI database. The CHIANTI database reproduces the vast majority of lines observed at these wavelengths. CHIANTI includes IDL (Interactive Data Language) routines to calculate optically thin synthetic spectra for equilibrium conditions. IDL routines to calculate theoretical line intensities required for
electron density or temperature diagnostics and emission measure studies are also included. The CHIANTI atomic database and supporting IDL routines are available by anonymous FTP.
%K atomic data - astronomical data bases: miscellaneous - ultraviolet: general - Sun: atmosphere - stars: atmosphere

%R 1997A&AS..125..175B
%J-182
%A Beuzit J.-L., Mouillet D., Lagrange A.-M., Paufique J.
%T A stellar coronograph for the COME-ON-PLUS adaptive optics system. I. Description and performance.
%M ds4420
%F 1997.09.20
%B The detection of faint emissions very close to much brighter objects is required in several different fields of astrophysics, for example in the search for planetary disks. We present here a coronograph that we built to work with come-on-plus, the ESO adaptive optics system, high angular resolution being of key importance in allowing observations close to a central, occulted object. The first results are presented and analyzed in order to establish the performance of this
instrument in terms of contrast and detectability of faint emissions close to a central star.
%K atmospheric effects - methods: data analysis - instrumentation: miscellaneous - stars: circumstellar matter

%R 1997A&AS..125..183M
%J-193
%A Munoz-Tunon C., Vernin J., Varela A.M.
%T Night-time image quality at Roque de los Muchachos Observatory.
%M ds5876
%F 1997.09.20
%B Nine months' seeing statistics at the Observatorio del Roque de los Muchachos (ORM) are presented. Measurements were taken with a differential image motion monitor on top of a 5-m high tower. From the whole campaign the mean seeing is 0.76", the median value is 0.64" and 7% of the time the seeing is better than 0.3". The best seeing measured is 0.17". A seasonal variation is noticeable, better seeing conditions appearing during summer, which corresponds to the
occurrence of a well-defined inversion layer due to the high prevalence of trade winds. During the summer, 50% of the time seeing is better than 0.54", value which drops to 0.46" during June, with a narrow distribution (rms=0.17"). These figures place the ORM among, or better than, the best astronomical sites (Paranal and La Silla, Chile) where seeing statistics are available. When inspecting individual nights, it sporadically happens that seeing deteriorates abruptly
and slowly recovers, with a 1.2-hour exponential decay time. This phenomenon is interpreted in terms of meteorological instabilities (gravity waves) which trigger a turbulent regime.
%K atmospheric effects - site testing

%R 1997A&AS..125..195C
%J-205
%A Chaplin W.J., Elsworth Y., Howe R., Isaak G.R., McLeod C.P., Miller B.A., New R.
%T Techniques used in the analysis of data collected by the Birmingham Solar-Oscillations Network (BiSON). II. Frequency domain analysis & data merging.
%M ds4986
%F 1997.09.20
%B The Birmingham Solar-Oscillations Network (BiSON) consists of 6 solar observatories dedicated to the collection of full-disc solar Doppler velocity data - these data are sensitive to the lowest spatial degrees of oscillation (0 <=l<=4). In Paper I of this series, we described the calibration of raw data from the BiSON instruments to produce solar velocity residuals representing the oscillations of the Sun's surface. In this paper, we discuss the combination of velocity
residuals into time series - including a thorough discussion of the treatment of data overlaps between sites - and the analysis of the power spectra computed from such time series to derive the characteristics of the acoustic modes.
%K Sun: oscillations - methods: data analysis

%R 1997A&AS..125..207A
%J-217
%A Andronov I.L.
%T Method of running parabolae: Spectral and statistical properties of the smoothing function.
%M ds1214
%F 1997.09.20
%B Analytic expressions in a general form are derived for the expectation of functions related to the smoothing the astronomical signals using local approximations with additional weights. No restrictions are made on distribution of the times of the signal. Applications are made for polynomial fits of orders 0 and 2 and weights p(z)=1 and (1-z^2^)^2^. These variable weights ensure that the smoothing function will be both continuous and differentiable, which is important for
determining the extrema and the shape of the variations. Special attention is paid to evenly spaced time series data, which if their number is large enough will allow one to obtain analytic expressions for the main functions.
%K methods: analytical; data analysis; numerical; statistical