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Intermediate-Brightness Equatorial Spectrophotometric Standards
We have obtained spectral energy distributions for 41 7m 8m stars nearthe celestial equator (δ=±3°). The λλ31007600 Å spectral range is studied with a spectral resolution of 50Å. The relative rms error in the visible is 1 2%, increasing to 35% towards the edges of the wavelength interval studied. All stars arereferenced to a single standard, the circumpolar star HD 221525. Thesynthetic colors of common stars are compared with those observed infour photometric systems: U BV, W BV R, uvby, and that of the TYCHOcatalog. The program stars are recommended as secondaryspectrophotometric standards.
| Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Radial velocities have been determined for a sample of 2930 B2-F5 stars,95% observed by the Hipparcos satellite in the north hemisphere and 80%without reliable radial velocity up to now. Observations were obtainedat the Observatoire de Haute Provence with a dispersion of 80Ä,mm(-1) with the aim of studying stellar and galactic dynamics.Radial velocities have been measured by correlation with templates ofthe same spectral class. The mean obtained precision is 3.0 km s(-1)with three observations. A new MK spectral classification is estimatedfor all stars. Based on observations made at the Haute ProvenceObservatory, France and on data from The Hipparcos Catalogue, ESA.Tables 4, 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.htm
| The Tokyo PMC catalog 90-93: Catalog of positions of 6649 stars observed in 1990 through 1993 with Tokyo photoelectric meridian circle
The sixth annual catalog of the Tokyo Photoelectric Meridian Circle(PMC) is presented for 6649 stars which were observed at least two timesin January 1990 through March 1993. The mean positions of the starsobserved are given in the catalog at the corresponding mean epochs ofobservations of individual stars. The coordinates of the catalog arebased on the FK5 system, and referred to the equinox and equator ofJ2000.0. The mean local deviations of the observed positions from theFK5 catalog positions are constructed for the basic FK5 stars to comparewith those of the Tokyo PMC Catalog 89 and preliminary Hipparcos resultsof H30.
| Absolute proper motions for the calibration of the HIPPARCOS proper motion system
Absolute proper motions of 48 Hipparcos stars in nine fields distributedover the northern hemisphere are presented. The proper motions have beenrecently used as part of the Bonn program for the extragalactic link ofthe Hipparcos proper motion system. We describe methods which have ledto the absolute proper motions of the major part of the Bonn fields forthe link. For six fields the extragalactic calibration was achievedusing the bright quasar in the centre of the field. In addition, data ofthree fields of globular clusters were included. For these fields thelink to an extragalactic reference system was performed by stars, whoseabsolute proper motions with respect to galaxies were determined onplates of the Lick astrograph. In addition, we used for the link in onefield plates from the ESO Schmidt telescope in combination withmeasurements from glass copies of the Palomar Sky Survey. The accuracyof a single proper motion is of the order of 2 to 3 mas/a for eachcoordinate. Table 2 is also available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html}
| A catalog of far-ultraviolet point sources detected with the fast FAUST Telescope on ATLAS-1
We list the photometric measurements of point sources made by the FarUltraviolet Space Telescope (FAUST) when it flew on the ATLAS-1 spaceshuttle mission. The list contains 4698 Galactic and extragalacticobjects detected in 22 wide-field images of the sky. At the locationssurveyed, this catalog reaches a limiting magnitude approximately afactor of 10 fainter than the previous UV all-sky survey, TDl. Thecatalog limit is approximately 1 x 10-14 ergs A sq cm/s,although it is not complete to this level. We list for each object theposition, FUV flux, the error in flux, and where possible anidentification from catalogs of nearby stars and galaxies. Thesecatalogs include the Michigan HD (MHD) and HD, SAO, the HIPPARCOS InputCatalog, the Position and Proper Motion Catalog, the TD1 Catalog, theMcCook and Sion Catalog of white dwarfs, and the RC3 Catalog ofGalaxies. We identify 2239 FAUST sources with objects in the stellarcatalogs and 172 with galaxies in the RC3 catalog. We estimate thenumber of sources with incorrect identifications to be less than 2%.
| High ion absorption through the Galactic halo: Contributions from H I gas in the presence of hot gas?
We have studied HST/FOS far ultraviolet spectra of AGNs. We observedthat Galactic Halo absorption in the 3C 273 sight line has large C IVand Si IV equivalent widths compared to the other Galactic halo sightlines in our sample. The 3C 273 sight line is near the edge of RadioLoop I, which is also one of the brightest soft X-ray sources in thesky. An attempt has been made to study the effect of this loop oninterstellar absorption. We have observed, with IUE, an A star (HD108228) which is near to the 3C 273 sight line and believed to be at adistance beyond the loop. We used stellar modeling to deconvolve stellarfrom interstellar lines. The results of our analysis are presented. Wealso have observations of PKS 1351+640 which has a high Si IV equivalentwidth and whose sight line crosses a high velocity 21 cm cloud whichabuts on soft X-ray emitting gas. It is possible that surface effects inregions of soft X-ray and H I emission produce the strong high ionabsorption though processes such as turbulent mixing layers, shocks, orthermal conduction. The Galactic halo absorption equivalent widths inthe spectra of these and 4 other AGNs in the ions C II, C IV, Si II, SiIV, Al II, and Al III are presented.
| A method for the correction of proper motions of stars around an extragalactic object in photographic astrometry
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1991A&A...241..303D&db_key=AST
| Vacuum ultraviolet imagery of the Virgo cluster region
The results are reported of an experiment using the UV imager aboard anattitude-controlled S520 type sounding rocket. The total UV fluxes ofgalaxies in the Virgo Cluster as well as the flux level of the diffuseUV background around the cluster were measured. The data on NGC 4486 andNGC 4472 confirm the variation in the degree of the 'turnup' below 200nm in the energy spectrum of the total light of elliptical galaxies. Attwo-color diagram of galaxies of visual/near-UV/vacuum UV indicates thatcolors of spiral galaxies are distributed within a strip andwell-correlated with the morphological type, while elliptical galaxiesare located differently from spiral galaxies.
| Precise positions in the FK4 system for 120 radio source reference stars
Positions are given in the FK4 system for 120 primary reference starsgrouped around the optical counterparts of 11 extragalactic radiosources. The observations were made in 1979 and 1980 with the 6-in.transit circle of the U.S. Naval Observatory. The results reported hererepresent the first step in a three-tiered process to determineastrometric positions of the optical counterparts referred to the systemof the FK4. One application of such positions is the determination of anearly inertial optical reference frame, which eventually may becompared to a reference frame at radio wavelengths.
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Osservazione e dati astrometrici
| Costellazione: | Vergine |
| Ascensione retta: | 12h26m00.84s |
| Declinazione: | +02°02'31.2" |
| Magnitudine apparente: | 7.319 |
| Distanza: | 140.449 parsec |
| Moto proprio RA: | -44.5 |
| Moto proprio Dec: | 2.4 |
| B-T magnitude: | 7.399 |
| V-T magnitude: | 7.326 |
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