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|Arcsecond Positions of UGC Galaxies|
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
|An Einstein X-Ray Survey of Optically Selected Galaxies. I. Data|
We present the results of a complete Einstein imaging proportionalcounter X-ray survey of optically selected galaxies from theShapley-Ames Catalog, the Uppsala General Catalogue, and the EuropeanSouthern Observatory Catalog. Well-defined optical criteria are used toselect the galaxies, and X-ray fluxes are measured at the opticallydefined positions. The result is a comprehensive list of X-ray detectionand upper limit measurements for 1018 galaxies. Of these, 827 haveeither independent distance estimates or radial velocities. Associatedoptical, redshift, and distance data have been assembled for thesegalaxies, and their distances come from a combination of directlypredicted distances and those predicted from the Faber-Burstein GreatAttractor/Virgocentric infall model. The accuracy of the X-ray fluxeshas been checked in three different ways; all are consistent with thederived X-ray fluxes being of <=0.1 dex accuracy. In particular,there is agreement with previously published X-ray fluxes for galaxiesin common with a 1991 study by Roberts et al. and a 1992 study byFabbiano et al. The data presented here will be used in further studiesto characterize the X-ray output of galaxies of various morphologicaltypes and thus to enable the determination of the major sourcescontributing to the X-ray emission from galaxies.
|The nature of unidentified 12 micron IRAS sources at high Galactic latitudes|
A sample of 47 previously uncatalogued objects located above a Galacticlatitude of 50 deg, and detected at 12 microns by the IRAS, is studiedusing near-infrared photometry. Ground-based observations show that theobjects consist primarily of late-type M giant stars withlong-wavelength excesses probably due to emission from dust associatedwith mass loss. The sample contains one oxygen-rich giant starundergoing rapid mass loss; an extremely cool (1230 K) carbon star12560-1656 that may be as far as 10 kpc away; and a luminious quasar13349-2438. The absence of nearby, low-luminosity infrared sources inthis sample limits the space density of field brown dwarf stars. Thefact that almost all the IRAS 12 micron sources have stellarcounterparts visible on both the red and blue Palomar Observatory SkySurvey prints provides a tool for discriminating ordinary red stars.
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