Search Publications
The Ultraviolet Absorption Spectrum of 3C 273
Junkkarinen, V.; Schneider, D. P.; Jannuzi, B. T. +3 more
We identify six Lyα absorption systems with equivalent widths greater than 0.2 A in the ultraviolet spectrum of the nearby quasar 3C 273, more than expected on the basis of extrapolations of the observed number of Lyα clouds seen at large redshifts. Two Lyα lines appear to be produced by gas in the Virgo Cluster or by the halos of galaxies associa…
First Results from the Faint Object Camera: SN 1987A
Panagia, N.; Boksenberg, A.; Kirshner, R. P. +18 more
We present the first images of SN 1987A taken on day 1278 after outburst with the Faint Object Camera on board the Hubble Space Telescope. The supernova is well detected and resolved spatially in three broadband ultraviolet exposures spanning the 1500-3800 A range and in a narrow-band image centered on the [O III] λ5007 line. Simple uniform disk f…
Premaximum Observations of the Type IA SN 1990N
Filippenko, Alexei V.; Shields, Joseph C.; Kirshner, Robert P. +4 more
Spectroscopic and photometric observations of SN 1990N were obtained at ultraviolet and optical wavelengths, beginning 14 days before maximum light. The early observations reveal important differences from spectra of SN Ia's around maximum light. Photometry and spectroscopy obtained after maximum show that SN 1990N is a typical SN Ia and that most…
The Featureless Continua and Hydrogen Lines of Seyfert 2 Galaxies
Wilson, A. S.; Ward, M. J.; Antonucci, R. R. J. +2 more
We present optical and ultraviolet spectra taken in similar sized large apertures for 15 Seyfert 2 galaxies. Measurements of emission-line strengths of Lyα, Hα, and Hβ are used together with measurements of the ultraviolet slopes to estimate the ratio of recombination photons to ionizing photons. The photon ratios indicate that the ionizing contin…
Tomographic Separation of Composite Spectra: The Components of the O-Star Spectroscopic Binary AO Cassiopeiae
Gies, Douglas R.; Bagnuolo, William G., Jr.
The UV photospheric lines of the short-period, double-lined O-star spectroscopic binary AO Cas are analyzed. Archival data from IUE (16 spectra uniformly distributed in orbital phase) were analyzed with a tomography algorithm to produce the separate spectra of the two stars in six spectral regions. The spectral classifications of the primary and s…
The Imaging Performance of the Hubble Space Telescope
Faber, S. M.; Holtzman, Jon A.; Burrows, Christopher J. +4 more
Problems with the HST instantaneous imaging performance and pointing performance are discussed. Optical tests have clearly demonstrated that the HST suffers from spherical aberration. The top level specification was that 70 percent of the energy be focused in a 0.1 in. radius, but the present, and close to optimum, focus setting gives only about 1…
The Discovery of a Young Radio Galaxy at Z = 2.390: Probing Initial Star Formation at Z 2pt< -11.5pt-3pt approximately 3.0
Chambers, K. C.; Windhorst, Rogier A.; Matthews, Keith +7 more
We present the discovery of a weak radio galaxy from the Leiden Berkeley Deep Survey at a redshift of 2.390, the faint optical and IR counterpart of the steep-spectrum, compact radio source 53W002. Its λ dependent optical continuum morphology is compact with linear size ~10-35 kpc (H_0_= 50, q_0_ = 0). In redshifted Lyα, the galaxy is somewhat mor…
The EXOSAT High Galactic Latitude Survey
Tagliaferri, G.; Beuermann, K.; Branduardi-Raymont, G. +9 more
A survey of serendipitous sources performed in the very soft X-ray band (0.05-2.0 keV) using the EXOSAT imaging telescopes is presented. The survey covers 783 square degrees of high Galactic latitude sky and includes 210 serendipitous sources which define a complete (flux-limited) sample. An extensive program of optical and radio observations toge…
3C 390.3: Modeling Variable Profile Humps
Veilleux, Sylvain; Zheng, Wei; Grandi, Steven A.
A comparison of the Hα and Hβ profiles of the radio galaxy 3C 390.3 at different epochs shows that the Hβ/Hα ratio is significantly higher in the line "humps" than in the rest of the profiles. No humps are found in the Lyα profile, although Lyα is as broad as the Balmer lines. Therefore, the profile humps are probably produced in a region of highe…
Accretion Mechanisms in the Be/X-Ray Transient System A0535+26
Stella, L.; Motch, C.; Janot-Pacheco, E. +1 more
We present four EXOSAT observations of the Be/X-ray transient pulsar HDE 245770/A0535+26 obtained at various phases of the 111d period. On all occasions, a faint X-ray flux is detected from the source (Fx = 1.5-3.0 × 10-10 ergs cm-2 s-1) which corresponds to Lx (1-20 keV) = 2.5 × 10…