%R 1998A&AS..127..101S
%J-105
%A Seeberger R., Saurer W.
%T Penetrating the ``zone of avoidance''. V. An optical survey for hidden galaxies in the region 90{deg}<=l<=110{deg}, -10{deg} <= b <=+10{deg}
%M ds1381
%F 1998.01.16
%B As the fifth part in our series of papers on galaxies in the ``zone of avoidance" (ZOA) of the Milky Way we present 1346 new galaxy candidates discovered during a systematic search on Palomar Observatory Sky Survey (POSSI-E) red-sensitive prints. The region searched comprises 400 square degrees at 90{deg}<=l<=110{deg}, -10{deg}<=b<=+10{deg}. We list galactic and equatorial coordinates, maximum optical diameters and diameters of the core, if visible, both for the red- and
blue-sensitive POSS prints. An asymmetric distribution of the galaxies with respect to the galactic equator is found and can most probably be attributed to the galactic warp.
We also present radial velocities for 14 galaxies measured for the first time which are located in the region where a branch of the Pisces Perseus Supercluster is approaching the ZOA from the south (l=~90{deg}, b=~-10{deg}).
%K catalogs - (ISM): dust, extinction - galaxies: general - large scale structure of the Universe

%R 1998A&AS..127..107G
%J-115
%A Goncalves A.C., Veron P., Veron-Cetty M.-P.
%T Miscellaneous observations of active galactic nuclei. II.
%M ds1377
%F 1998.01.16
%B We observed 37 AGN candidates and classified them on the basis of their spectroscopic properties; three are confirmed QSOs, one is a BL Lac object, nine are Seyfert 1 galaxies, four Seyfert 2s, while twenty are HII regions.
%K galaxies: active - galaxies: Seyfert - galaxies: BL Lacertae objects: general - galaxies: quasars: general - galaxies: starburst

%R 1998A&AS..127..117P
%J-118
%A Prugniel P., Zasov A., Busarello G., Simien F.
%T A catalogue of spatially resolved kinematics of galaxies: Bibliography.
%M ds1396
%F 1998.01.16
%B We present a catalogue of galaxies for which spatially resolved data on their internal kinematics have been published; there is no a priori restriction regarding their morphological type. The catalogue lists the references to the articles where the data are published, as well as a coded description of these data: observed emission or absorption lines, velocity or velocity dispersion, radial profile or 2D field, position angle.
%K catalogs - galaxies general - galaxies: kinematics and dynamics

%R 1998A&AS..127..119F
%J-138
%A Filipovic M.D., Pietsch W., Haynes R.F., White G.L., Jones P.A., Wielebinski R., Klein U., Dennerl K., Kahabka P., Lazendic J.S.
%T A radio continuum study of the Magellanic Clouds. VI. Discrete sources common to radio and X-ray surveys of the Magellanic Clouds.
%M ds6224
%F 1998.01.16
%B By comparing Parkes telescope radio surveys with the X-ray ROSAT All-Sky Survey (RASS) we have found 71 discrete sources of both radio and X-ray emission in the Large Magellanic Cloud (LMC). These 71 sources are mainly supernova remnants (SNRs) and SNR candidates (36), and background sources (27). For six of the sources we have no proposed identification and the other two are HII regions. A source-intensity comparison of the radio and X-ray sources shows very little
correlation, but we note that the strongest SNRs at both radio and X-ray frequencies are young SNRs from Population I. Six new LMC SNR candidates are proposed. From the radio flux density of the SNRs we have estimated the SNR birth rate to be one every 100 (+/-20) yr and the star-formation rate (SFR) to be 0.7 (+/-0.2) M_{sun}_/yr. A similar comparison was undertaken for the Small Magellanic Cloud (SMC), but instead of the RASS we used a roster of pointed observations made
with the ROSAT Position Sensitive Proportional Counter (PSPC). This comparison resulted in 27 sources in common between the Parkes radio and ROSAT PSPC surveys. Two new SMC sources are proposed for SNR candidates. The SMC SNR birth rate was estimated to be one every 350 (+/-70) yr and the SFR was estimated to be 0.15 (+/-0.05) M_{sun}_/yr.
%K galaxies: Magellanic Clouds - radio continuum: galaxies - X-rays: galaxies - ISM: supernova remnants (SNRs) - ISM: HII regions

%R 1998A&AS..127..139C
%J-144
%A Castilho B.V., Gregorio-Hetem J., Spite F., Spite M., Barbuy B.
%T Li-rich giants: A survey based on IRAS colours.
%M ds1386
%F 1998.01.16
%B In a previous work we studied the IRAS colours of known Li-rich red giants and showed that they have flux ratios F_12_/F_25_ and F_25_/F_60_ in well defined ranges. By using this result as a selection criterion, we prepared a list of 280 IRAS Point Source candidates to be Li-rich giant stars. Up to the present we have obtained spectra for 57% of our target list. We identified five stars showing a strong LiI 670.079nm line and six ones with a Li line of medium strength.
Most of the candidates show features typical of normal giants having circumstellar dust, as indicated by their IRAS colours.
%K stars: abundances - infrared: stars - stars: late type

%R 1998A&AS..127..145B
%J-152
%A Bade N., Engels D., Voges W., Beckmann V., Boller T., Cordis L., Dahlem M., Englhauser J., Molthagen K., Nass P., Studt J., Reimers D.
%T The Hamburg/RASS Catalogue of optical identifications.
%M h0405
%F 1998.01.16
%B We present the Hamburg/RASS Catalogue of optical identifications (HRC). The catalogue contains optical information about objects inside the error circles of ROSAT All-Sky Survey (RASS) sources. The information was gathered from objective prism and direct plates taken by the Hamburg Quasar Survey (HQS). The plates enable an effective selection of several X-ray emitting classes of objects, as there are galaxies, AGN, QSOs, galaxy clusters and several types of galactic stars,
in particular M dwarfs, hot white dwarfs and cataclysmic variables. In the current state (November 1996) the HRC contains information about 3847 X-ray positions and covers about 8480deg^2^ of the high galactic latitude (|b|>20{deg}) northern sky. For 81.2% of the X-ray sources a plausible optical counterpart is given. The counterparts of the remaining sources are probably faint (B>18.5) AGN and galaxy clusters. The HRC is available electronically together with finding
charts taken from the digitized direct HQS plates.
%K X-ray sources: general - galaxies - stars

%R 1998A&AS..127..153K
%J-165
%A Kijak J., Kramer M., Wielebinski R., Jessner A.
%T Pulse shapes of radio pulsars at 4.85 GHz.
%M h0469
%F 1998.01.16
%B We present pulse shapes of 87 pulsars at 4.85GHz. Pulse widths and flux densities are measured. The frequency dependence of the profile shape and the pulse width is discussed. Our data base has been combined with other published data to generate flux spectra between 1.4GHz and 5GHz. The mean flux spectral index has a value -1.9. Our analysis shows that pulsar emission spectra are steeper at higher frequencies.
%K pulsars: general - radiation mechanisms: miscellaneous

%R 1998A&AS..127..167R
%J-179
%A Richtler T., Grebel E.K., Subramaniam A., Sagar R.
%T V, I CCD photometry of metal-rich globular clusters: NGC 6528.
%M ds1111
%F 1998.01.16
%B We present CCD photometry in V and I for the metal-rich globular cluster NGC 6528. A comparison with previous photometry reveals discrepancies of the order 0.1 to 0.2mag in V, emphasizing the need for independent photometry. As found previously, the giant branch (or the asymptotic giant branch, which cannot be distinguished) of the cluster extends to V-I=7. Population synthesis in V-I must take these red stars into account in order to understand integrated red colours
of bulge populations. Currently available theoretical isochrones do not reproduce the shape of the RGB/AGB. The derivation of reliable values for reddening, distance and metallicity of NGC 6528 is hampered by uncertainties in the extrapolation to high metallicity, which dominate the absolute error rather than the photometric uncertainty does. Together with other properties (old age derived from HST data, high radial velocity), this object is more likely a member of the bulge
than of the disk population.
%K Galaxy: globular clusters: general; individual: NGC 6528 - galaxy abundances - stars: late-type - HR diagram

%R 1998A&AS..127..181H
%J-184
%A Han F., Mao R.Q., Lu J., Wu Y.F., Sun J., Wang J.S., Pei C.C., Fan Y., Tang G.S., Ji H.R.
%T New detections of H_2_O maser sources on the 13.7 m radio telescope of Purple Mountain Observatory.
%M ds1321
%F 1998.01.16
%B Observations of H_2_O maser sources on the 13.7m radio telescope of Purple Mountain Observatory from 1990 Aug. to 1994 Jan. are summarized. For searching new water masers, the total number of search candidates is about 360, with 110 objects detected. Among them are 96 new detections. A list of the new detections and their spectra are presented.
%K masers - radio lines: general; ISM; stars

%R 1998A&AS..127..185N
%J-200
%A Nyman L.-A., Hall P.J., Olofsson H.
%T SiO masers in OH/IR stars, proto-planetary and planetary nebulae.
%M ds5033
%F 1998.01.16
%B We present a search for SiO masers towards a sample of 126 objects including OH/IR stars, proto-planetary and planetary nebulae. All objects are classified as oxygen-rich, and most of them are associated with OH or H_2_O masers. SiO masers were found only in variable objects like the OH/IR stars and a few objects classified as proto-planetary nebulae, but with variable central stars that may be part of binary systems. In one object, OH 15.7+0.8, which appears to be varying
irregularly and most likely recently left the AGB, an SiO maser was tentatively detected. Thus, we conclude that variability and SiO maser emission are closely linked, and that SiO masers disappear very soon after a star has reached the end of the AGB, when pulsation and mass loss cease.
%K stars: AGB and post-AGB - masers - radio lines: stars

%R 1998A&AS..127..201M
%J-206
%A Manfroid J., Burnet M., Renson P.
%T Variations of Ap stars in the Geneva system.
%M ds6225
%F 1998.01.16
%B The photometric behaviour of 21 Ap stars has been analyzed from observations obtained in the Geneva system. Variability has been detected for 9 Ap stars, as well as for a star which initially was a comparison star. Preliminary values for the periods are presented as well as an analytical description of the light curves.
%K stars: chemically peculiar; variable

%R 1998A&AS..127..207C
%J-215
%A Cutispoto G.
%T Long-term monitoring of active stars. VII. UBV(RI)_c_ photometry collected in March 1991.
%M ds1393
%F 1998.01.16
%B In the framework of an extensive program focusing on the global properties and evolution of active stars, high-precision UBV(RI)_c_ photometry of 19 selected stars, collected at the European Southern Observatory over the 15-31 March 1991 interval is presented. Significant evolution of the light curves, period variations and evidence for long-term variability of the global degree of spottedness are found. Most of the spectral classifications are discussed. A flare event was
detected for the star HD 127535 = V 841 Cen. These observations contribute to the establishment of a time-extended photometric database which can give important clues on topics such as the stability of spotted areas, differential rotation, solar-like cycles and the correlation between inhomogeneities at different atmospheric levels.
%K stars: activity - stars: flare - stars: late-type - stars: variables - techniques: photometric - stars: individual: HD 127535

%R 1998A&AS..127..217D
%J-232
%A D'Odorico V., Cristiani S., D'Odorico S., Fontana A., Giallongo E.
%T The absorption spectrum of the QSO PKS 2126-158 (z_em_=3.27) at high resolution.
%M ds6155
%F 1998.01.16
%B Spectra of the z_em_ = 3.268 quasar PKS 2126-158 have been obtained in the range {lambda}{lambda}4300-6620{AA} with a resolution R=~27000 and an average signal-to-noise ratio s/n=~25 per resolution element. The list of the identified absorption lines is given together with their fitted column densities and Doppler widths. The modal value of the Doppler parameter distribution for the Ly{alpha} lines is =~25km/s. The column density distribution can be described by a
power-law dn / dN {prop.to} N^-{beta}^ with {beta}=~1.5. 12 metal systems have been identified, two of which were previously unknown. In order to make the column densities of the intervening systems compatible with realistic assumptions about the cloud sizes and the silicon to carbon overabundance, it is necessary to assume a jump beyond the He II edge in the spectrum of the UV ionizing background at z ~3 a factor 10 larger than the standard predictions for the integrated
quasar contribution. An enlarged sample of C IV absorptions (71 doublets) has been used to analyze the statistical properties of this class of absorbers strictly related to galaxies. The column density distribution is well described by a single power-law, with {beta}=1.64 and the Doppler parameter distribution shows a modal value b_CIV_=~14km/s. The two point correlation function has been computed in the velocity space for the individual components of C IV features. A
significant signal is obtained for scales smaller than 200-300km/s, {xi}(30<{DELTA}v<90km/s)=33+/-3. A trend of decreasing clustering amplitude with decreasing column density is apparent, analogously to what has been observed for Ly{alpha} lines.
%K quasars: absorption lines - quasars: individual: PKS 2126-158

%R 1998A&AS..127..233D
%J-242
%A Djurasevic G.
%T An interpretation of light curves of SV Camelopardalis by the inverse-problem method.
%M ds6119
%F 1998.01.16
%B The paper is devoted to the problem of the determination of the orbital and physical parameters of the active eclipsing binary SV Cam on the basis of the interpretation of photometric observations made by Patkos (1982, Comm. Konkoly Obs., No. 80) during the period 1973-1981. The problem is solved in two stages: by obtaining a synthetic light curve in the case when the parameters of the corresponding Roche model Djurasevic, 1992Ap&SS.196..241D) are given a priori (direct problem), and by determining the
parameters of the model for which the best fit between the synthetic light curve and the observations is achieved (inverse problem) Djurasevic, 1992Ap&SS.197...17D). A total of 18 light curves are analysed in the framework of the Roche model, involving one and two spotted regions on the primary component of the system (Sp G3 V), for the temperature contrast between the spotted area and the surrounding photosphere A_s_=T_s_/T_1_=0.65. The basic parameters of the system and of the
spotted areas are estimated. Throughout the whole set of the analysed light curves, a double spot model fits the observations satisfactorily. A single spot model yields a poorer fit, where the basic system parameters obtained by analysing the individual light curves show stronger variations about a mean value. That indicates that the single spot model cannot successfully reproduce the SV Cam light curve changes during the analysed period. According to the obtained results the
spotted areas are formed at high latitudes and cover a significant part of the stellar surface. No clear cyclicity of the system's activity is noted from the analysed observations. There are some indications that spotted areas at high latitudes (above 70{deg}) correspond to an enhanced activity. Since the system's period is short (P=0.59)d, the presence of spotted regions at high latitudes can be explained by the dynamo mechanism for rapid rotators Schuessler & Solanski
1992A&A...264L..13S). During the analysed period the spotted areas tend to fall into a specially active longitude sectors at high latitudes, near stellar polar regions. Due to a selection effect it is possible that a more extensive observational material would correct this result to some extent. The light curve analysis allowed an estimation of the system parameters and of the active spotted regions.
%K stars: activity; eclipsing binaries-stars; individual: SV Cam - methods data analysis

%R 1998A&AS..127..243B
%J-249
%A Beskrovnaya N.G., Pogodin M.A., Yudin R.V., Franco G.A.P., Vieira S.L.A., Evans A.
%T Cyclic phenomena in the circumstellar gaseous envelope of the candidate Herbig A0e star HD 163296.
%M ds6203
%F 1998.01.16
%B We present new results of a spectroscopic and polarimetric investigation of the candidate young Herbig Ae/Be star HD 163296. Twenty two spectra of this object near the H{alpha}, Hei 5876 and DNai lines had been obtained in 1992-1995 at the Astrophysical National Laboratory of Brazil (LNA). In addition, forty seven high-resolution spectra in H{alpha} and H{beta} were obtained at the ESO (Chile) in 1991-1992. VRI-polarimetry (about forty measurements of the Stokes parameters
Q,U,V in each passband) were carried out at the SAAO (South Africa) in July 17-30, 1995. Striking profile variability has been found in all the lines on time scales from hours to months. Analysis of the profiles revealed manifestations of a remote cool shell which is in active interaction with the variable kinematically stratified stellar wind. Signs of cyclic positional variations of the H{alpha} and H{beta} emission peaks were observed during five nights in July, 1991.
Sinusoidal variations of the linear polarization parameters detected in July, 1995 are explained in the framework of a model involving magnetized gaseous condensation, rotating in the envelope with the period of 15 days. Marginal detection of circular polarization is also reported.
%K line: profiles - polarization - stars: circumstellar matter - stars: individual (HD 163296) - stars: mass loss - stars: pre-main sequence

%R 1998A&AS..127..251H
%J-255
%A Huensch M., Schmitt J.H.M.M., Voges W.
%T The ROSAT all-sky survey catalogue of optically bright late-type giants and supergiants.
%M ds1380
%F 1998.01.16
%B We present X-ray data for all late-type (A, F, G, K, M) giants and supergiants (luminosity classes I to III-IV) listed in the Bright Star Catalogue that have been detected in the ROSAT all-sky survey. Altogether, our catalogue contains 450 entries of X-ray emitting evolved late-type stars, which corresponds to an average detection rate of about 11.7 percent. The selection of the sample stars, the data analysis, the criteria for an accepted match between star and X-ray
source, and the determination of X-ray fluxes are described.
%K stars: activity - stars: coronae - stars: late-type - X-rays: stars - catalogs

%R 1998A&AS..127..257E
%J-267
%A Erdem A., Gueduer N.
%T The orbital period study and photometric analysis of XY Ursae Majoris.
%M ds5690
%F 1998.01.16
%B Photoelectric observations of the eclipsing binary XY UMa have been carried out in B and V colours at the Ege University Observatory. Combining these newly obtained data with the previous ones available in the literature, the problem pertaining to the orbital period of the system has been investigated through a detailed description of the O-C diagram. The sinusoidal and secular changes have been found. Such variations of the orbital period have been examined in terms of
three plausible mechanisms, namely (i) a light-time effect due to a third body, (ii) the orbital period modulation due to magnetic activity cycle of a component star, and (iii) a mass loss case in which the ejected material escapes out from the binary system. A combination of a magnetic activity cycle mechanism and a mass loss case is found to reproduce satisfactorily the period changes. Further, the observed photoelectric light curves of the system have been analyzed with
the Wilson-Devinney approach. This analysis shows that the asymmetries of the light curves of XY UMa can be interpreted in terms of cool star-spot covering 7% of the stellar photosphere of the primary component of this binary. The system is found to be a {beta} Lyrae type detached binary. The absolute elements of the system are also deduced.
%K stars: binaries - close - stars: individual: XY UMa - fundamental parameters - starspots

%R 1998A&AS..127..269H
%J-276
%A Huchtmeier W.K., Skillman E.D.
%T An optically directed HI search for new dwarf members of the M 81 group.
%M ds1372
%F 1998.01.16
%B We present a search for neutral hydrogen (HI) emission from optically identified dwarf galaxy candidates in the larger M81 group area. Of 136 candidates, 68 galaxies have been detected (this corresponds to a detection rate of ~49%). Most of the detected galaxies are background objects and fail to be classified as dwarfs. Many known dwarfs in the M81 group have been detected, but no new members have been discovered.
%K galaxies: irregular - radio lines: galaxies - galaxies: individual: M 81 - galaxies clusters M 81 group

%R 1998A&AS..127..277K
%J-294
%A Kuenzli M., North P.
%T Are metallic A-F giants evolved Am stars? Rotation and rate of binaries among giant F stars.
%M ds5844
%F 1998.01.16
%B We test the hypothesis of Berthet (1991A&A...251..171B) which foresees that Am stars become giant metallic A and F stars (defined by an enhanced value of the blanketing parameter {DELTA}m_2_ of the Geneva photometry) when they evolve. If this hypothesis is right, Am and metallic A-FIII stars need to have the same rate of binaries and a similar distribution of vsini. From our new spectroscopic data and from vsin i and radial velocities in the literature, we show that it is not the case.
The metallic giant stars are often fast rotators with vsin i larger than 100km/s, while the maximum rotational velocity for Am stars is about 100km/s. The rate of tight binaries with periods less than 1000 days is less than 30% among metallic giants, which is incompatible with the value of 75% for Am stars (Abt & Levy 1985ApJS...59..229A). Therefore, the simplest way to explain the existence of giant metallic F stars is to suggest that all normal A and early F stars might go
through a short ``metallic" phase when they are finishing their life on the main sequence. Besides, it is shown that only giant stars with spectral type comprised between F0 and F6 may have a really enhanced {DELTA}m_2_ value, while all A-type giants seem to be normal.
%K stars: binaries: spectroscopic - stars: chemically peculiar - stars: evolution - stars: rotation - stars: {delta} Scuti

%R 1998A&AS..127..295P
%J-297
%A Popovic L.C., Dimitrijevic M.S.
%T Stark broadening parameters for Kr II lines from 5s-5p transitions.
%M ds1317
%F 1998.01.16
%B With the development of space-borne spectroscopy, spectral line parameters for a large number of lines become of increasing interest for astrophysics. To provide Stark broadening data for ion lines from complex spectra, we present here calculated Stark widths for 37 Kr II lines from the 5s-5p transition. The calculations were performed by using a modified semiempirical approach. The obtained Stark widths are on average in satisfactory agreement with available experimental
data.
%K atomic data - lines, profiles

%R 1998A&AS..127..299M
%J-308
%A Michard R.
%T New techniques for deriving bulge and disk models of two-component galaxies.
%M ds6026
%F 1998.01.16
%B A new method is introduced to ``separate" the bulge and disk components of early-type galaxies, i.e. S0's and disky E's, viewed at such inclinations that their isophotes depart significantly from ellipses. In our approach, the two components are assumed to have concentric and coaxial ellipitical isophotes of arbitrary surface brightness (SuBr) and ellipticity profiles. These four functions are to be determined by comparing calculated and easily measured quantities, i.e.
the harmonics of the SuBr along suitable reference ellipses. The principle of the method is straightforward and its implementation very easy in favourable cases. There are difficulties however with truly edge-on galaxies, where the assumption of elliptical isophotes is perhaps no more valid for the disk, and with objects of such inclinations that the geometrical signature of the two-components structure tends to vanish. Our techniques have been tested with a number of
calculated model objects, and with 9 real galaxies, observed at sub-arcsec resolution at the CFHT or at the Pic du Midi. The results are compared with those of other authors, sometimes involving more uncertain assumptions: the one of negligible disk contributions to the minor axis SuBr is unsatisfactory for S0 galaxies.
%K galaxies: elliptical and lenticulars, cD - galaxies: fundamental parameters - galaxies: photometry

%R 1998A&AS..127..309S
%J-318
%A Schwarz U., Kurths J., Kliem B., Krueger A., Urpo S.
%T Multiresolution analysis of solar mm-wave bursts.
%M ms5845
%F 1998.01.16
%B Two methods of multi-scale time series analysis are applied to solar mm-wavelength flux time profiles in order to assess the diagnostic power of these tools for the exploration of nonlinear energy release processes. Both the multiresolution analysis (MRA), a method based on the wavelet transform, and the structure function analysis (SFA) permit the treatment of non-stationary time series. In addition, the MRA offers a local decomposition of the scaling behavior of the flux
variations. Our main emphasis is directed at a decomposition of the contributions of the different time scales to the overall flux profile. The methods yield consistent values of the ``spectral index" which describes the scalings contained in the time series. We find that time profiles of bursts are qualitatively analogous to fractional Brownian motion (fBm), possessing long-range temporal correlations. Such correlations are not found in quiet Sun observations. The MRA of six
solar mm-wave bursts shows that the radio flux is always composed of contributions from a broad range of time scales. Also during the main phase of bursts, which appears to be structurally analogous to the pre- and post-burst phases at a resolution limit of 1 s, flux fluctuations are enhanced in a broad range of time scales. This suggests that the mm-wave bursts are composed of unresolved elements, just as the pre- and post-burst time profiles. The underlying energy release
thus appears to be fragmentary. These results are discussed in terms of the avalanche model and plasma physical models for solar energy release events.
%K Sun: radio radiation - Sun: flares - methods: data analysis

%R 1998A&AS..127..319K
%J-325
%A Kienel C., Kimeswenger S.
%T Covered data structures I. The algorithm
%M h0247
%F 1998.01.16
%B Many algorithms separating or detecting groups of similiar objects (for example the extraction of groups lying in a color-color-diagram) are based on two statistical methods: the Kernel Method (Silverman, 1986, Density Estimation for Statistics and Data Analysis. Chapman and Hall.) or the Likelihood Statistic (van der Waerden 1957, Mathematische Statistik, Die Grundlagen der Mathematischen Wissenschften, Band LXXXVII. Springer-Verlag.). These standard methods have one or more restrictions (e.g. known number or differentiability of the groups, ...). We present here a new powerful algorithm and show results worked out with artificial data sets.
The algorithm is based on Recursive Restoration Methods (neither on the Likelihood Statistic (Sutherland & Saunders 1992) nor on the Kernel Method (De Jager et al. 1986) and allows to detect substructures in a data set, even if they are overlapped or superimposed by any kind of dominating main structure. In comparison to the other methods mentioned above there are no restrictions concerning the form and the dimension of the components lying in the data set. The algorithm
is easy to handle and therefore opens a wide range of applications for many fields of science (see Boller et al. 1992).
%K methods: statistical - astronomical data bases: miscellaneous

%R 1998A&AS..127..327S
%J-333
%A Sodemann M., Thomsen B.
%T Crowded-field photometry from HST-imaging.
%M ds6134
%F 1998.01.16
%B We present a thorough investigation of stellar photometry based on HST imaging of crowded fields at 85" and 10" from the centre of the high-surface brightness elliptical galaxy M 32. The Principal Investigators of the present archive data have elsewhere presented an impressive colour-magnitude diagram of the field at 85". Based on the same data we enlarge on their photometric analysis and supplement with error estimators that more clearly show the implications of severe
image crowding on the stellar photometry. We show that the faintest stars (I>25.0, V>26.0) are found too bright by several tens of a magnitude. For the field at 10" we conclude that it is not possible to obtain reliable stellar photometry, standard deviations being larger than 0.4mag. Artificial-star experiments show that only very few of the brightest stars of the luminosity function can be expected to represent single objects, the majority being either spurious or not
as bright as measured. The paper as such introduces and demonstrates basic guide lines which may be used when dealing with stellar photometry of severely crowded fields.
%K methods: data analysis - galaxies: elliptical - galaxies: individual: M 32 - galaxies: stellar content

%R 1998A&AS..127..335F
%J-352
%A Fadda D., Slezak E., Bijaoui A.
%T Density estimation with non-parametric methods.
%M ds6152
%F 1998.01.16
%B One key issue in several astrophysical problems is the evaluation of the density probability function underlying an observational discrete data set. We here review two non-parametric density estimators which recently appeared in the astrophysical literature, namely the adaptive kernel density estimator and the Maximum Penalized Likelihood technique, and describe another method based on the wavelet transform. The efficiency of these estimators is tested by using extensive
numerical simulations in the one-dimensional case. The results are in good agreement with theoretical functions and the three methods appear to yield consistent estimates. However, the Maximum Penalized Likelihood suffers from a lack of resolution and high computational cost due to its dependency on a minimization algorithm. The small differences between kernel and wavelet estimates are mainly explained by the ability of the wavelet method to take into account local gaps in
the data distribution. This new approach is very promising, since smaller structures superimposed onto a larger one are detected only by this technique, especially when small samples are investigated. Thus, wavelet solutions appear to be better suited for subclustering studies. Nevertheless, kernel estimates seem more robust and are reliable solutions although some small-scale details can be missed. In order to check these estimators with respect to previous studies, two
galaxy redshift samples, related to the galaxy cluster A3526 and to the Corona Borealis region, have been analyzed. In both these cases claims for bimodality are confirmed at a high confidence level.
%K methods: data analysis, statistical; galaxies: clusters: general

%R 1998A&AS..127..353S
%J-353
%A Samain D. 
%T (Erratum) A high spectral resolution atlas of the balloon ultraviolet spectrum of the Sun: 1950-2000{AA}.
%F 1998.01.16
%B Erratum to Astron. astrophys. Suppl. Ser. 113 (1995) 237-255.