Search Publications
Steps toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. IX. Ultraviolet Observations of Fairall 9
Shull, J. M.; Malkan, M. A.; Martin, P. G. +53 more
An 8 month monitoring campaign on the Seyfert 1 galaxy Fairall 9 has been conducted with the International Ultraviolet Explorer in an attempt to obtain reliable estimates of continuum-continuum and continuum-emission-line delays for a high-luminosity active galactic nucleus (AGN). While the results of this campaign are more ambiguous than those of…
Steps toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XI. Intensive Monitoring of the Ultraviolet Spectrum of NGC 7469
Shull, J. M.; Malkan, M. A.; Nandra, K. +54 more
From 1996 June 10 to July 29, the International Ultraviolet Explorer monitored the Seyfert 1 galaxy NGC 7469 continuously in an attempt to measure time delays between the continuum and emission-line fluxes. From the time delays, one can estimate the size of the region dominating the production of the UV emission lines in this source. We find the s…
A Catalog of Morphological Types in 10 Distant Rich Clusters of Galaxies
Smail, Ian; Ellis, Richard S.; Dressler, Alan +4 more
We present catalogs of objects detected in deep images of 11 fields in 10 distant clusters obtained using WFPC-2 on board the Hubble Space Telescope. The clusters span the redshift range z = 0.37-0.56 and are the subject of a detailed ground- and space-based study to investigate the evolution of galaxies as a function of environment and epoch. The…
A Coronal Spectrum in the 500--1610 Angstrom Wavelength Range Recorded at a Height of 21,000 Kilometers above the West Solar Limb by the SUMER Instrument on Solar and Heliospheric Observatory
Wilhelm, K.; Curdt, W.; Schühle, U. +4 more
We present a solar coronal spectrum recorded by the extreme UV spectrometer SUMER on the Solar and Heliospheric Observatory. The spectrum was taken between 21:28 UT on 1996 June 25 and 02:47 UT on 1996 June 26, at a height of 21,000 km above the west equatorial limb with the slit oriented in the north-south direction. At the time of the observatio…
Hubble Space Telescope Imaging of Compact Steep-Spectrum Radio Sources
Golombek, D.; Sparks, W. B.; Macchetto, F. +8 more
We present Hubble Space Telescope WFPC2 images taken through a broad red filter (F702W) of 30 Third Cambridge Catalog compact steep spectrum (CSS) radio sources. We have overlaid radio maps taken from the literature on the optical images to determine the radio-optical alignment and to study detailed correspondence. All CSS sources for which the re…
Physical Conditions of the Coronal Line Region in Seyfert Galaxies
Ferland, Gary J.; Korista, Kirk T.; Ferguson, Jason W.
The launch of the Infrared Space Observatory and new atomic data have opened a window for the study of high-ionization gas in active galactic nuclei (AGNs). We present the results of a large number of photoionization simulations of the ``coronal line'' region in AGNs, employing new atomic data from the Opacity and Iron Projects. Our grid of line e…
Hubble Space Telescope Snapshot Survey of 3CR Radio Source Counterparts. II. Radio Galaxies with Z > 0.5
Baum, Stefi A.; McCarthy, Patrick J.; Sparks, William B. +5 more
We present images of 51 3CR radio galaxies with 0.5 < z < 2.5 obtained in the snapshot mode with the Hubble Space Telescope. The images are short exposures with the Planetary Camera and the F702W filter. A wide range of morphologies and surface brightness are seen on subarcsecond scales. Some are very strongly nucleated, and their light is m…
Galaxy Morphology without Classification: Self-organizing Maps
Griffiths, Richard E.; Ratnatunga, Kavan U.; Naim, Avi
We examine a general framework for visualizing data sets of high (greater than 2) dimensionality and demonstrate the framework by taking the morphology of galaxies at moderate redshifts as an example. The distributions of various populations of such galaxies are examined in a space spanned by four purely morphological parameters. Galaxy images are…
Hubble Space Telescope Wide Field Planetary Camera 2 Imaging of the Crab Nebula. I. Observational Overview
Blair, William P.; Davidson, Kris; Henry, Richard B. C. +3 more
We present Hubble Space Telescope WFPC2 images of a portion of the Crab Nebula supernova remnant obtained using narrow passband filters. These images show a wide range of filament morphologies including small individual isolated knots, long smooth arcs, and chaotic filament complexes, with evidence that some filament cores are far denser and coole…
Gamma-Ray Burst Arrival Time Localizations: Simultaneous Observations by Mars Observer, Compton Gamma Ray Observatory, and ULYSSES
Hurley, K. C.; Fishman, G. J.; Kouveliotou, C. +12 more
Between 1992 October 4 and 1993 August 1, concurrent coverage by the Compton Gamma Ray Observatory (CGRO), Mars Observer (MO), and Ulysses spacecraft was obtained for 78 gamma-ray bursts (GRBs). Although most of these were below the MO and Ulysses thresholds, nine were positively detected by all three spacecraft, with data quality adequate for qua…