Contents
Images
Upload your image
DSS Images Other Images
Related articles
Optically bright active galactic nuclei in the ROSAT-Faint source catalogue
To build a large, optically bright, X-ray selected AGN sample we havecorrelated the ROSAT-FSC catalogue of X-ray sources with the USNOcatalogue limited to objects brighter than O=16.5 and then with the APSdatabase. Each of the 3212 coincidences was classified using theslitless Hamburg spectra. 493 objects were found to be extended and 2719starlike. Using both the extended objects and the galaxies known frompublished catalogues we built up a sample of 185 galaxies withO_APS<17.0 mag, which are high-probability counterparts of RASS-FSCX-ray sources. 130 galaxies have a redshift from the literature and foranother 34 we obtained new spectra. The fraction of Seyfert galaxies inthis sample is 20%. To select a corresponding sample of 144high-probability counterparts among the starlike sources we searched forvery blue objects in an APS-based color-magnitude diagram. Forty-onewere already known AGN and for another 91 objects we obtained newspectra, yielding 42 new AGN, increasing their number in the sample to83. This confirms that surveys of bright QSOs are still significantlyincomplete. On the other hand we find that, at a flux limit of 0.02count s-1 and at this magnitude, only 40% of all QSOs aredetected by ROSAT.Tables 2, 3 and 4 are only available in electronic form athttp://www.edpsciences.org
| 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.
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
Catalogs and designations:
|
