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An Atlas of Spectrophotometric Landolt Standard Stars
We present CCD observations of 102 Landolt standard stars obtained withthe Ritchey-Chrétien spectrograph on the Cerro TololoInter-American Observatory 1.5 m telescope. Using stellar atmospheremodels, we have extended the flux points to our six spectrophotometricsecondary standards, in both the blue and the red, allowing us toproduce flux-calibrated spectra that span a wavelength range from 3050Å to 1.1 μm. Mean differences between UBVRI spectrophotometrycomputed using Bessell's standard passbands and Landolt's publishedphotometry were determined to be 1% or less. Observers in bothhemispheres will find these spectra useful for flux-calibrating spectra,and through the use of accurately constructed instrumental passbands,will be able to compute accurate corrections to bring instrumentalmagnitudes to any desired standard photometric system (S-corrections).In addition, by combining empirical and modeled spectra of the Sun,Sirius, and Vega, we calculate and compare synthetic photometry toobserved photometry taken from the literature for these three stars.
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| On the sytematic accuracy of the equatorial UBVRI standard stars
The considerable systematic difference in B-V between northern andsouthern measurements of the equatorial UBVRI standard stars arestudied. It is found that the northern data (Landolt 1983) are muchcloser to the original UBV system than the southern ones. The situationis less clear in the case of V and U-B.
| A radio optical reference frame. III - Additional radio and optical positions in the Southern Hemisphere
Radio and optical positions are presented for southern hemisphereextragalactic sources from the Parkes 2.7 GHz survey. Sixty-one sourceswere observed with Mark III VLBI at 8.4 GHz between Tidbinbilla,Australia, and Hartebeesthoek, South Africa. The results presented arepart of the effort to establish a global reference frame of 400extragalactic radio sources. Radio positions with about 10 milliarcsecerrors have been estimated for 39 sources not previously in the presentradio reference frame catalog, and provisional positions were obtainedfor two additional sources, bringing the total number of catalog sourcesto 276. The principal source of error is the uncalibrated ionosphere. Ofthe remaining sources five were completely undetected, six were eithertoo faint or too resolved, and nine had previous catalog positions.Optical positions on the FK5 system have also been measured for foursouthern sources using prime focus plates from the Anglo-Australian 4 mtelescope with an accuracy of 0.06 arcsec. This raises to 40 the numberof radio sources with accurately measured positions for their opticalcounterparts.
| UBV(RI)c photometry of equatorial standard stars - A direct comparison between the northern and southern systems
UBV(RI)c photometry of 212 stars from Landolt's list of equatorialstandards is presented. The observations are tied to the system definedby Cousin's E-region standards. A comparison of the present results withLandolt's reveals reasonably good agreement for (V-R)c and (V-I)c, butmarked systematic differences for (B-V) and (U-B). The UBV systems ofCousins and Landolt are evidently not the same and both probably differfrom Johnson's original system.
| Selection of standard stars for photometric observations with the 91-cm reflector at Okayama
Not Available
| The active nucleus of M81 and its history
Optical spectra obtained in subarcsecond seeing have been analyzed inorder to explore the emission-line properties and stellar dynamics ofthe nuclear region (r of less than 8 kpc) in M81. Stellar velocitydispersions suggest a central mass of order 10 to the 7th solar masses.In addition to the broad Balmer lines, emission from forbidden Fe VII isnoted at the nucleus which probably derives from an intermediate-densityregion. Strong and narrow forbidden N I emission, peaking sharply at thenucleus, is observed. It is noted that the presence of other forbiddenlines, such as forbidden O III 5007-A lines, show complex multicomponentprofiles at the nucleus which may complicate physical interpretation ofthe line-width/critical-density relations.
| The dynamics of SBO galaxies. I - The data
This is the first of several papers on the bar dynamics of SBO galaxies.The surface photometry and kinematic data for NGCs 1543, 1574, 4477,4754 and the SBa galaxy NGC 1291 are presented. These galaxies will formthe database for subsequent papers, which will examine in detail thenature of bars.
| The unusual box-shaped elliptical (?) galaxy IC 3370
IC 3370 is noted by this photometric and kinematic study to be more likethe bulges of disk galaxies than elliptical galaxies; seen nearlyedge-on, it is an S0pec rather than an elliptical galaxy, as originallyclassified. IC 3370 is also found to be a cylindrical rotator above theplane of the disk to a degree that is far in excess of previousobservations in box- or peanut-shaped bulges. In addition, it exhibits alarge amount of isophotal twisting throughout the bulge, which is noteasily reconciled with an oblate model's nearly edge-on view, but issuggestive of a merger or tidal-encounter history.
| UBV Photometry of Equatorial Stars
Not Available
| The kinematic properties of faint elliptical galaxies
Rotation curves and velocity dispersion profiles are obtained for 11faint elliptical galaxies, together with central velocity dispersionsfor an additional six faint ellipticals. It is noted that faintellipticals rotate more rapidly than bright ellipticals, and almost asrapidly as predicted by models with oblate figures and isotropicdistributions of residual velocities. No significant difference is foundbetween disk galaxy bulge rotational properties and ellipticals withsimilar absolute magnitudes, when ellipticity differences are taken intoaccount. Attention is given to the relation between central velocitydispersion and luminosity, and indication is found that it may besteeper at low luminosities. It may be possible to satisfy the empiricalcorrelation between rotation and luminosity, if the ellipticals formedin a clustering hierarchy, although the slow rotation of brightellipticals is difficult to reconcile with their high densities
| UBVRI photometric standard stars around the celestial equator
It is pointed out that accurate, internally consistent, and readilyaccessible standard star photometric sequences are necessary for thecalibration of the intensity and color data which astronomers obtain atthe telescope. The photometric results provided in connection with thepresent study represent the first part of an effort which is concernedwith the presentation of UBVRI photoelectric photometric standard starsin the magnitude range from 7 to 17 over as broad a range in color aspossible. All of the photometric observations were made with a 31034type photomultiplier used in a pulse counting mode. Some 15 to 25standard stars chosen from Cousins' lists (1973, 1976) in the E-regionswere observed with an 0.4-m telescope each night along with the programstars. UBVRI standard stars were observed periodically throughout thenight. Observations with a 0.9-m telescope were also conducted. TheUBVRI photoelectric observations take into account 223 stars.
| Spectral classifications for Landolt's celestial equatorial standard stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1979AJ.....84..783D&db_key=AST
| Equatorial UBVRI photoelectric sequences
From 1335 BVRI observations of 189 stars in selected areas 92-115,Landolt's (1973) network of faint UBV standards has been extended to RI. Of these stars, 173 have four or more observations. The (U-B) valuesof Landolt are adopted, and a well-observed equatorial faint-starnetwork is presented on the Johnson UBVRI photometric system.
| Distances to eclipsing binaries. III - Masses, radii, and absolute magnitudes of 96 stars
Distances to, and absolute magnitudes of, 96 components of eclipsingbinaries with well-determined absolute dimensions have been computedusing V-R photometry. The calculations take into account interstellarreddening, which is estimated from existing UBV and uvby-betaphotometry, as well as photometric proximity effects. The resultingabsolute magnitudes, dimensions, and masses are compared with zero-agemain sequences predicted by theory. Theory is in good agreement with theobserved data for stars more massive than the sun if a composition (X,Y, Z) = (0.66 + or - 0.03, 0.303 + or - 0.03, 0.037 + or - 0.005) ischosen. The corresponding helium-to-hydrogen number ratio is 0.115 + or- 0.02, in agreement with previous estimates.
| Catalog of Indidual Radial Velocities, 0h-12h, Measured by Astronomers of the Mount Wilson Observatory
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJS...19..387A&db_key=AST
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| קבוצת-כוכבים: | סכסטנט |
| התרוממות ימנית: | 09h55m35.15s |
| סירוב: | -01°07'34.7" |
| גודל גלוי: | 7.987 |
| מרחק: | 194.553 פארסק |
| תנועה נכונה: | 26.5 |
| תנועה נכונה: | -66.4 |
| B-T magnitude: | 9.393 |
| V-T magnitude: | 8.104 |
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