Search Publications

Abundance of Interstellar Carbon toward zeta Ophiuchi

Ebbets, Dennis C.; Savage, Blair D.; Cardelli, Jason A. +1 more

We report on the detection of the weak intersystem transition of semiforbidden C II 2325 A in the sight line toward Zeta Oph using the Ech-B mode of the Goddard High-Resolution Spectrograph. The measured equivalent width of the semiforbidden C II line is W(lambda) = 0.52 +/- 0.12 mA, implying a C II column density of 1.80 (+/- 0.42) x 10 exp 17 at…

Multiwavelength Monitoring of the BL Lacertae Object PKS 2155-304. I. The IUE Campaign

Maraschi, L.; Chiappetti, L.; Tagliaferri, G. +26 more

Daily monitoring of PKS 2155 - 304 with the IUE satellite throughout 1991 November has revealed dramatic, large-amplitude, rapid variations in the ultraviolet flux of this BL Lac object. Many smaller, rapid flares are superposed on a general doubling of the intensity. During the 5^d^ period when sampling was roughly continuous, the rapid flaring h…

The Hubble Space Telescope Snapshot Survey. IV. A Summary of the Search for Gravitationally Lensed Quasars

Gould, A.; Maoz, D.; Meylan, G. +7 more

We report the concluding results of the HST Snapshot Survey for gravitationally lensed quasars. New observations of 153 high-luminosity z > 1 quasars are presented, bringing to 498 the total number of quasars observed in the survey. The new observations do not reveal new candidates for gravitational lensing. We present tables summarizing all of…

X-Ray Observations of the Warm Absorber in NGC 3783

Nandra, K.; Turner, T. J.; Fabian, A. C. +2 more

We present a high signal-to-noise ROSAT position sensitive proportional counter (PSPC) observation of the Seyfert 1 galaxy NGC 3783. The 0.1-2.5 keV spectrum shows strong evidence for an absorption edge most likely associated with O VII-VIII. Such a feature, which has now been detected in a number of PSPC spectra (Nandra et al.; Nandra & Pound…

The Crab Pulsar in the Visible and Ultraviolet with 10 Microsecond Time Resolution

Dolan, J. F.; Nelson, M. J.; Percival, J. W. +8 more

Observations of PSR 0531+21 with the High Speed Photometer on the HST in the visible in October 1991 and in the UV in January 1992 are presented. The time resolution of the instrument was 10.74 microsec; the effective time resolution of the light curves folded modulo the pulsar period was 21.5 microsec. The main pulse arrival time is the same in t…

A Determination of the Distance to the High-Velocity Cloud Complex M

Kuntz, K. D.; Danly, Laura; Albert, C. E.

Variations of the Ultraviolet Fe II and Balmer Continuum Emission in the Seyfert Galaxy NGC 5548

Filippenko, A. V.; Netzer, H.; Shapovalova, A. I. +13 more

We present measurements of the Balmer continuum/Fe II emission blend (the "small blue bump") between 2160 and 4130 A in the Seyfert galaxy NGC 5548. The measurements are from spectra obtained as part of the combined space-based and ground-based monitoring program of this object in 1988- 1989. An iterative scheme is used to determine and subtract t…

Winds from Accretion Disks: Ultraviolet Line Formation in Cataclysmic Variables

Shlosman, Isaac; Vitello, Peter

Winds from accretion disks in cataclysmic variable stars are ubiquitous. Observations by IUE reveal P Cygni-shaped profiles of high-ionization lines which are attributed to these winds. We have studied the formation of UV emission lines in cataclysmic variables by constructing kinematical models of biconical rotating outflows from disks around whi…

High-Resolution Mid-Infrared Imaging and Astrometry of the Nucleus of the Seyfert Galaxy NGC 1068

Wilson, A. S.; Beichman, C. A.; Braatz, J. A. +2 more

We have used the Goddard Infrared Array Camera to obtain a high resolution (0.7" FWHM) image of the nucleus of NGC 1068 at 12.4 microns. The location of the 12.4 micron peak relative to the peak of the optical continuum has also been determined. The brightest part of the infrared nuclear peak is found to be elongated almost N-S (P.A. ~8^deg^), wit…

The Hubble Space Telescope Quasar Absorption Line Key Project. III. First Observational Results on Milky Way Gas

Schneider, Donald P.; Savage, Blair D.; Sargent, W. L. W. +11 more

We report on absorption by Milky Way disk and halo gas seen in Quasar Absorption Line Key Project measurements of 15 quasars obtained with the Faint Object spectrograph (FOS) of the Hubble Space Telescope (HST). The measurements extend from 1150 to 3270 A for four objects and from 1600 to 3270 A for 11 objects and have a velocity resolution (FWHM)…