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|Formalism and quality of a proper motion link with extragalactic objects for astrometric satellite missions|
The accuracy of the link of the proper motion system of astrometricsatellite missions like AMEX and GAIA is discussed. Monte-Carlo methodswere used to simulate catalogues of positions and proper motions ofquasars and galaxies to test the link. The main conclusion is, thatfuture satellite missions like GAIA may be ``self-calibrated'' by theirmeasurements of QSOs, while additional measurements from radio stars orHST-data are needed to calibrate the less deep reaching astrometricsatellite missions of AMEX type.
|The FIRST Bright Quasar Survey. II. 60 Nights and 1200 Spectra Later|
We have used the Very Large Array (VLA) FIRST survey and the AutomatedPlate Measuring Facility (APM) catalog of the Palomar Observatory SkySurvey I (POSS-I) plates as the basis for constructing a newradio-selected sample of optically bright quasars. This is the firstradio-selected sample that is competitive in size with current opticallyselected quasar surveys. Using only two basic criteria, radio-opticalpositional coincidence and optical morphology, quasars and BL Lacobjects can be identified with 60% selection efficiency; the efficiencyincreases to 70% for objects fainter than 17 mag. We show that a moresophisticated selection scheme can predict with better than 85%reliability which candidates will turn out to be quasars. This paperpresents the second installment of the FIRST Bright Quasar Survey(FBQS), with a catalog of 636 quasars distributed over 2682deg2. The quasar sample is characterized and all spectra aredisplayed. The FBQS detects both radio-loud and radio-quiet quasars outto redshift z>3. We find a large population of objects ofintermediate radio loudness; there is no evidence in our sample for abimodal distribution of radio characteristics. The sample includes ~29broad absorption line quasars, both high and low ionization, and anumber of new objects with remarkable optical spectra.
|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.
|Catalogue of HI maps of galaxies. I.|
A catalogue is presented of galaxies having large-scale observations inthe HI line. This catalogue collects from the literature the informationthat characterizes the observations in the 21-cm line and the way thatthese data were presented by means of maps, graphics and tables, forshowing the distribution and kinematics of the gas. It containsfurthermore a measure of the HI extension that is detected at the levelof the maximum sensitivity reached in the observations. This catalogueis intended as a guide for references on the HI maps published in theliterature from 1953 to 1995 and is the basis for the analysis of thedata presented in Paper II. The catalogue is only available inelectronic form at the CDS via anonymous ftp 126.96.36.199 orhttp://cdsweb.u-strasbg.fr/Abstract.html
|An image database. II. Catalogue between δ=-30deg and δ=70deg.|
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
|A deep redshift survey of IRAS galaxies towards the Bootes void|
Redshifts were measured for a complete sample of galaxies detected bythe IRAS within 11.5 deg of the center of the void in Bootes discoveredby Kirshner et al (1981). There are 12 IRAS galaxies within the void asdefined by the above authors, seven of which were discovered in thissurvey. One of these has a companion at the same redshift. The resultingdensity of IRAS galaxies in the void is measured to be between 1/6 and1/3 of the average density; the uncertainty is dominated by Poissonstatistics. Good agreement is found between the selection function andnumber density derived from the present sample and those derived fromthe all-sky sample of Strauss (1989). The optical spectra of the newlyfound galaxies in the void are typical of IRAS galaxies in the field.
|Studies of IRAS sources at high galactic latitudes. IV - New redshifts and the spectroscopic properties of IRAS galaxies|
New redshifts, H-alpha line fluxes, and optical continuum fluxes forIRAS galaxies are presented. Most of the galaxies show emission linesstronger than those found in optically selected spiral galaxies andcharacteristic of normal H II regions, suggesting a burst of starformation as the basic energy source. There is considerable reddeningtoward the emission-line regions and toward the unobserved UV sources,most of the energy emerging in the infrared. A minority of the casesshow high-excitation emission lines, and these are also distinguished bytheir infrared colors, typical luminosities, and emission-linestrengths. Type 2 Seyferts outnumber type 1s by two to one.
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