Riccardo Giacconi

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In the construction of an X-ray selected sample of galaxy clusters for cosmological studies, we have assembled a sample of 495 X-ray sources found to show extended X-ray emission in the first processing of the ROSAT All-Sky Survey. The sample covers the celestial region with declination δ ≥ 0◦ and galactic latitude |bII | ≥ 20 ◦ and comprises sources with a(More)
An unusual double-lobed extended X-ray source (RX J105343+5735) is detected in the ROSAT ultra-deep HRI image of the Lockman Hole. The angular size of the source is 1.7× 0.7 arcmin and its X-ray flux is 2 × 10 erg cm s. R-band imaging from the Keck telescope revealed a marginal excess of galaxies brighter than R=24.5, but Keck LRIS spectroscopy of 24(More)
We present the X-ray Luminosity Function (XLF) of the ROSAT Deep Cluster Survey (RDCS) sample over the redshift range 0.05–0.8. Our results are derived from a complete flux-limited subsample of 70 galaxy clusters, representing the brightest half of the total sample, which have been spectroscopically identified down to the flux limit of 4 × 10−14 erg cm−2(More)
We present our first results from 130 ks of X–ray observations obtained with the Advanced CCD Imaging Spectrometer on the Chandra X–ray Observatory. The field is 0.096 square degrees and the detection limit is to a S/N ratio of 2. We reach a flux of 2 × 10−16 erg s−1 cm−2 in the 0.5-2 keV soft band and 2 × 10−15 erg s−1 cm−2 in the 2-10 keV hard band. Our(More)
Istituto Nazionale di Astrofisica (INAF) Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 European Southern Observatory, Karl-Schwarzschild-Strasse 2, Garching, D-85748, Germany Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, D-85741 Garching,(More)
  • Optical Spectroscopy, G P Szokoly, +16 authors A Zirm
  • 2004
We present the results of our spectroscopic follow-up program of the X-ray sources detected in the 942 ks exposure of the Chandra Deep Field South (CDFS). 288 possible counterparts were observed at the VLT with the FORS1/FORS2 spectrographs for 251 of the 349 Chandra sources (including three additional faint X-ray sources). Spectra and R-band images are(More)
X-ray emission from the Cygnus Loop was observed in the energy region around 0.2 to 1 kiloelectronvolt with a collector that focused x-rays along one dimension while scanning across the nebula. The total integrated intensity is 1.3x 10(-8) erg per square centimeter per second. The one-dimensional x-ray structure has the same angular size-about 3 degrees-as(More)
An unusual double-lobed extended X-ray source (RX J105343+5735) is detected in the ROSAT ultra-deep HRI image of the Lockman Hole. The angular size of the source is 1.7×0.7 arcmin2 and its X-ray flux is 2×10−14 erg cm−2 s−1. R-band imaging from the Keck telescope revealed a marginal excess of galaxies brighter than R=24.5, but Keck LRIS spectroscopy of 24(More)
High-resolution solar x-ray images were obtained with a rocket-borne grazing incidence telescope. The x-ray flare is large in extent, has fine strulctuire, and follows a neutral magnetic line. X-ray emitting coronal links interconnect active regions. The general coronal emission at the limb and several faint regions on the disc are observed.
The ROSATDeep Survey in the LockmanHole is the most sensitive X-ray survey performed to date, encompassing an exposure time of 207 ksec with the PSPC and a total of 1.32 Msec with the HRI aboard ROSAT. Here we present the complete catalogue of 50 X-ray sources with PSPC fluxes (0.5-2 keV) above 5.5 × 10−15 erg cm−2 s−1. The optical identifications are(More)