Search Publications
Scattered light models of the dust shell around HD 179821
Gledhill, T. M.; Takami, M.
The dust shell around the evolved star HD 179821 has been detected in scattered light in near-IR imaging polarimetry observations. Here, we subtract the contribution of the unpolarized stellar light to obtain an intrinsic linear polarization of between 30 and 40 per cent in the shell which seems to increase with radial offset from the star. The J …
The Host Galaxy and Environment of the z=1.195 Quasar 3C 190
Stockton, Alan; Ridgway, Susan E.
We present deep imaging and spectroscopic observations of the z=1.195 quasar 3C 190 and its immediate environment. The quasar is surrounded by an asymmetric, low surface brightness envelope in which there are also several galaxies with characteristic dimensions of 3-5 kpc. Some of these form a linear structure some 50 kpc long in projection, offse…
A case study of low-frequency waves at the magnetopause
Dandouras, I.; Belmont, G.; Lucek, E. +10 more
We present the study of one of the first magnetopause crossings observed by the four Cluster spacecraft simultaneously, on 10 December 2000. Although the delays between the crossings are very short, the features of the boundary appear quite different as seen by the different spacecraft, strongly suggesting the presence of a local curvature of the …
Investigation of Gravitational Lens Mass Models
Griffiths, Richard E.; Ratnatunga, Kavan U.; Knudson, Adam
We have previously reported the discovery of strong gravitational lensing by faint elliptical galaxies using the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telescope, and here we investigate their potential usefulness in placing constraints on lens mass models. We compare various ellipsoidal surface mass distributions, including tho…
Direct measurement of sub-pixel structure of the EPIC MOS CCD on-board the XMM//NEWTON satellite
Bennie, P. J.; Turner, M. J. L.; Abbey, A. F. +3 more
We have used a mesh experiment in order to measure the sub-pixel structure of the EPIC MOS CCDs on-board the XMM/NEWTON satellite. The EPIC MOS CCDs have 40 µm-square pixels which have an open electrode structure in order to improve the detection efficiency for low-energy X-rays. We obtained restored pixel images for various X-ray event grad…
New Rest Wavelength Determinations for Seven Mid-Infrared Fine-Structure Lines by ISO-SWS
Lutz, D.; Beintema, D. A.; Feuchtgruber, H.
Observations of the planetary nebulae NGC 6302, NGC 6543, and NGC 7027 by the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory (ISO) have been used to determine rest wavelengths of spectral lines. We report on improved accuracies for wavelengths of seven mid-infrared ionic fine-structure lines. Based on observations made…
Long-Term Multiwavelength Observations of GRS 1758-258 and the Advection-dominated Accretion Flow Model
Hailey, Charles J.; Kahn, Steven M.; Craig, William W. +9 more
We present a long-term multiwavelength light curve of Galactic black hole candidate GRS 1758-258 by combining previously published and archival data from Granat, ROSAT, the Compton Gamma Ray Observatory, the Rossi X-Ray Timing Explorer, BeppoSAX, ASCA, EXOSAT, and the Very Large Array. In addition, we include the first spectral results from the ba…
Mass segregation of different populations inside the cluster NGC 6101
Pulone, L.; Testa, V.; Marconi, G. +3 more
We have used ESO telescopes at La Silla and the Hubble Space Telescope (HST) in order to obtain accurate B, V, I CCD photometry for the stars located within 200arcsec ( =~ 2 half-mass radii, rh = 1.71arcmin ) from the center of the cluster NGC 6101. Color-Magnitude Diagrams (CMDs) extending from the red-giant tip to about 5 magnitudes b…
The combination of ground-based astrometric compilation catalogues with the HIPPARCOS Catalogue. II. Long-term predictions and short-term predictions
Wielen, R.; Dettbarn, C.; Lenhardt, H. +1 more
The combination of ground-based astrometric compilation catalogues, such as the FK5 or the GC, with the results of the ESA Astrometric Satellite HIPPARCOS produces for many thousands of stars proper motions which are significantly more accurate than the proper motions derived from the HIPPARCOS observations alone. In Paper I (Wielen, et al. 1999, …
The Tolman Surface Brightness Test for the Reality of the Expansion. II. The Effect of the Point-Spread Function and Galaxy Ellipticity on the Derived Photometric Parameters
Sandage, Allan; Lubin, Lori M.
To complete the Tolman surface brightness test on the reality of the expansion of the universe, we need to measure accurately the surface brightness profiles of the high-redshift galaxy sample. To quantify this accuracy, we investigate the effects of various sizes of point-spread functions composed of telescope diffraction, CCD pixel resolutions, …