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X-Ray-Emitting Stars Identified from the ROSAT All-Sky Survey and the Sloan Digital Sky Survey
The ROSAT All-Sky Survey (RASS) was the first imaging X-ray survey ofthe entire sky. Combining the RASS Bright and Faint Source Catalogsyields an average of about three X-ray sources per square degree.However, while X-ray source counterparts are known to range from distantquasars to nearby M dwarfs, the RASS data alone are often insufficientto determine the nature of an X-ray source. As a result, large-scalefollow-up programs are required to construct samples of known X-rayemitters. We use optical data produced by the Sloan Digital Sky Survey(SDSS) to identify 709 stellar X-ray emitters cataloged in the RASS andfalling within the SDSS Data Release 1 footprint. Most of these arebright stars with coronal X-ray emission unsuitable for SDSSspectroscopy, which is designed for fainter objects (g > 15 [mag]).Instead, we use SDSS photometry, correlations with the Two Micron AllSky Survey and other catalogs, and spectroscopy from the Apache PointObservatory 3.5 m telescope to identify these stellar X-raycounterparts. Our sample of 707 X-ray-emitting F, G, K, and M stars isone of the largest X-ray-selected samples of such stars. We derivedistances to these stars using photometric parallax relationsappropriate for dwarfs on the main sequence, and use these distances tocalculate LX . We also identify a previously unknowncataclysmic variable (CV) as a RASS counterpart. Separately, we usecorrelations of the RASS and the SDSS spectroscopic catalogs of CVs andwhite dwarfs (WDs) to study the properties of these rarer X-ray-emittingstars. We examine the relationship between (fX /fg) and the equivalent width of the Hβ emission line for 46X-ray-emitting CVs and discuss tentative classifications for a subsetbased on these quantities. We identify 17 new X-ray-emitting DA(hydrogen) WDs, of which three are newly identified WDs. We report onfollow-up observations of three candidate cool X-ray-emitting WDs (oneDA and two DB (helium) WDs); we have not confirmed X-ray emission fromthese WDs.Includes observations obtained with the Apache Point Observatory 3.5 mtelescope, which is owned and operated by the Astrophysical ResearchConsortium.
| 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.
| UBV Photometry of Stars whose Positions are Accurately Known
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1984A&AS...57..357O&db_key=AST
| Meridian observations made with the Carlsberg Automatic Meridian Circle at Brorfelde (Copenhagen University Observatory) 1981-1982
The 7-inch transit circle instrument with which the present position andmagnitude catalog for 1577 stars with visual magnitudes greater than11.0 was obtained had been equipped with a photoelectric moving slitmicrometer and a minicomputer to control the entire observationalprocess. Positions are reduced relative to the FK4 system for each nightover the whole meridian rather than the usual narrow zones. Thepositions of the FK4 stars used in the least squares solution are alsogiven in the catalog.
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