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Search for associations containing young stars (SACY). I. Sample and searching method
We report results from a high-resolution optical spectroscopic surveyaimed to search for nearby young associations and young stars amongoptical counterparts of ROSAT All-Sky Survey X-ray sources in theSouthern Hemisphere. We selected 1953 late-type (B-V~≥~0.6),potentially young, optical counterparts out of a total of 9574 1RXSsources for follow-up observations. At least one high-resolutionspectrum was obtained for each of 1511 targets. This paper is the firstin a series presenting the results of the SACY survey. Here we describeour sample and our observations. We describe a convergence method in the(UVW) velocity space to find associations. As an example, we discuss thevalidity of this method in the framework of the β Pic Association.
| Absolute magnitudes for late-type dwarf stars for Sloan photometry
We present a new formula for absolute magnitude determination forlate-type dwarf stars as a function of (g-r) and (r-i) for Sloanphotometry. The absolute magnitudes estimated by this approach arebrighter than those estimated by colour-magnitude diagrams, and theyreduce the luminosity function rather close to the luminosity functionof Hipparcos.
| The u'g'r'i'z' Standard-Star System
We present the 158 standard stars that define the u'g'r'i'z' photometricsystem. These stars form the basis for the photometric calibration ofthe Sloan Digital Sky Survey. The defining instrument system andfilters, the observing process, the reduction techniques, and thesoftware used to create the stellar network are all described. Webriefly discuss the history of the star selection process, thederivation of a set of transformation equations for theUBVRCIC system, and plans for future work.
| Two-colour photometry for 9473 components of close Hipparcos double and multiple stars
Using observations obtained with the Tycho instrument of the ESAHipparcos satellite, a two-colour photometry is produced for componentsof more than 7 000 Hipparcos double and multiple stars with angularseparations 0.1 to 2.5 arcsec. We publish 9473 components of 5173systems with separations above 0.3 arcsec. The majority of them did nothave Tycho photometry in the Hipparcos catalogue. The magnitudes arederived in the Tycho B_T and V_T passbands, similar to the Johnsonpassbands. Photometrically resolved components of the binaries withstatistically significant trigonometric parallaxes can be put on an HRdiagram, the majority of them for the first time. Based on observationsmade with the ESA Hipparcos satellite.
| The ROSAT Bright Survey: II. Catalogue of all high-galactic latitude RASS sources with PSPC countrate CR > 0.2 s-1
We present a summary of an identification program of the more than 2000X-ray sources detected during the ROSAT All-Sky Survey (Voges et al.1999) at high galactic latitude, |b| > 30degr , with countrate above0.2 s-1. This program, termed the ROSAT Bright Survey RBS, isto more than 99.5% complete. A sub-sample of 931 sources with countrateabove 0.2 s-1 in the hard spectral band between 0.5 and 2.0keV is to 100% identified. The total survey area comprises 20391deg2 at a flux limit of 2.4 x 10-12 ergcm-2 s-1 in the 0.5 - 2.0 keV band. About 1500sources of the complete sample could be identified by correlating theRBS with SIMBAD and the NED. The remaining ~ 500 sources were identifiedby low-resolution optical spectroscopy and CCD imaging utilizingtelescopes at La Silla, Calar Alto, Zelenchukskaya and Mauna Kea. Apartfrom completely untouched sources, catalogued clusters and galaxieswithout published redshift as well as catalogued galaxies with unusualhigh X-ray luminosity were included in the spectroscopic identificationprogram. Details of the observations with an on-line presentation of thefinding charts and the optical spectra will be published separately.Here we summarize our identifications in a table which contains opticaland X-ray information for each source. As a result we present the mostmassive complete sample of X-ray selected AGNs with a total of 669members and a well populated X-ray selected sample of 302 clusters ofgalaxies with redshifts up to 0.70. Three fields studied by us remainwithout optical counterpart (RBS0378, RBS1223, RBS1556). While the firstis a possible X-ray transient, the two latter are isolated neutron starcandidates (Motch et al. 1999, Schwope et al. 1999).
| Observations of Double Stars. XVIII.
Micrometer observations of 1350 pairs in 1995-1997 are listed.
| An Optical Atlas of Extreme Ultraviolet Explorer (EUVE) Sources
The Extreme Ultraviolet Explorer (EUVE) has been detecting EUV sourcessince its launch in June 1992. Positions of 540 sources have been madeavailable to the community by the EUVE team. We have extracted 7' X 7'images centered on these 540 EUVE sources from the Space TelescopeScience Institute digitized sky archives. We present these images asmosaic finder charts to aid observers trying to identify EUVE sources,or to characterize known sources. (SECTION: Atlases)
| The Second Extreme-Ultraviolet Explorer Source Catalog
We present the second catalog of extreme-ultraviolet objects detected bythe Extreme-Ultraviolet Explorer. The data include (1) all-sky surveydetections from the initial 6 month scanner-survey phase, (2) additionalscanner detections made subsequently during specially programmedobservations designed to fill in low-exposure sky areas of the initialsurvey, (3) sources detected with deep-survey-telescope observationsalong the ecliptic, (4) objects detected by the scanner telescopesduring targeted spectroscopy observations, and ( 3) other observations.We adopt an innovative source detection method that separates the usuallikelihood function into two parts: an intensity diagnostic and aprofile diagnostic. These diagnostics allow each candidate detection tobe tested separately for both signal-to-noise ratio and conformance withthe known instrumental point-spread function. We discuss the dependenceof the false-alarm rate and the survey's completeness on the survey'ssensitivity threshold. We provide three lists of the EUV sourcesdetected: the all-sky survey detections, the deep-survey detections, andsources detected during other phases of the mission. Each list givespositions and intensities in each wave band. The total number of objectslisted is 734. For approximately 65% of these we also provide plausibleoptical, UV, radio, and/or X-ray identifications.
| The first Extreme Ultraviolet Explorer source catalog
The Extreme Ultraviolet Explorer (EUVE) has conducted an all-sky surveyto locate and identify point sources of emission in four extremeultraviolet wavelength bands centered at approximately 100, 200, 400,and 600 A. A companion deep survey of a strip along half the eclipticplane was simultaneously conducted. In this catalog we report thesources found in these surveys using rigorously defined criteriauniformly applied to the data set. These are the first surveys to bemade in the three longer wavelength bands, and a substantial number ofsources were detected in these bands. We present a number of statisticaldiagnostics of the surveys, including their source counts, theirsensitivites, and their positional error distributions. We provide aseparate list of those sources reported in the EUVE Bright Source Listwhich did not meet our criteria for inclusion in our primary list. Wealso provide improved count rate and position estimates for a majorityof these sources based on the improved methodology used in this paper.In total, this catalog lists a total of 410 point sources, of which 372have plausible optical ultraviolet, or X-ray identifications, which arealso listed.
| Extreme Ultraviolet Explorer Bright Source List
Initial results from the analysis of the Extreme Ultraviolet Explorer(EUVE) all-sky survey (58-740 A) and deep survey (67-364 A) arepresented through the EUVE Bright Source List (BSL). The BSL contains356 confirmed extreme ultraviolet (EUV) point sources with supportinginformation, including positions, observed EUV count rates, and theidentification of possible optical counterparts. One-hundred twenty-sixsources have been detected longward of 200 A.
| Analysis of Neckel and Chini standard stars in the UBVRI photometric system
This paper studies the list of 60 faint standard stars of Neckel andChini (1980) in the UBVRI Johnson photometric system. We have re-reducedthe standard stars using our own method of reduction from a large numberof selected observations made at the Observatorio Astronomico Nacionaland at the Centro Astronomico Hispano-Aleman, both at Calar Alto, Spain,and at the Observatorio del Roque de los Muchachos, La Palma Island,Spain. The reduction method used is explained and the results are givenfor the four colors used: (B-V), (U-B), (V-R), and (V-I), together withthe V magnitude, that is, we have corrected many standard stars for eachcolor and magnitude. These results are supported with graphs whereresidual color is plotted against corresponding color (or magnitude).Finally, our (V-R) and (V-I) results are compared to those of Taylor etal. (1989), with a good correspondence.
| The properties of the Neckel-Chini VRI system
Cousins (1980) data for 54 of the standard stars of Neckel and Chini(1980) and published measurements are used to investigate the propertiesof the Neckel-Chini VRI system. For red stars, this system diverges fromthe Johnson (1962) system, despite frequent claims of identity betweenthe two. The Neckel-Chini and Cousins systems, however, are closelycomparable. Both of these conclusions were previously reached in a paperby Bessell (1983); fair to good quantitative agreement with his resultsare obtained. Reddening ratios, the scatter in the Neckel-Chinistandard-star data, and the effect of this scatter on publishedmeasurements for program stars, are discussed. Transformations from theNeckel-Chini system to the Cousins system are given.
| G. P. Kuiper's spectral classifications of proper-motion stars
Spectral classifications are listed for over 3200 stars, mainly of largeproper motion, observed and classified by Kuiper during the years1937-1944 at the Yerkes and McDonald Observatories. While Kuiper himselfpublished many of his types, and while improved classifications are nowavailable for many of these stars, much of value remains. For many ofthe objects, no other spectral data exist.
| Sixty faint UBVRI standards
A list of 60 faint UBVRI standards is presented. Their UBV magnitudesare in the system introduced by Johnson (1955) and their V-R and V-Icolors are in the system of the Arizona Tonantzintla catalogue byIriarte et al. (1965). These stars are spread over an equatorial belt atan angle less than 30 deg, so that they can be observed as well fromnorthern as from southern sites.
| Micrometer Measures of Double Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1961ApJS....6....1K&db_key=AST
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