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Multiwavelength Monitoring of the BL Lacertae Object PKS 2155-304. IV. Multiwavelength Analysis
Maraschi, L.; Tagliaferri, G.; Pian, E. +47 more
Simultaneous X-ray, ultraviolet, optical, infrared, and radio monitoring data were used to test and constrain models of continuum emission from the BL Lacertae object PKS 2155-304. Intensively sampled ultraviolet and soft X-ray light curves showed a clear temporal correlation, with the X-rays leading the ultraviolet by 2-3 hr. This lag was found t…
Hubble Space Telescope Sample of Radio-loud Quasars: Ultraviolet Spectra of the First 31 Quasars
Netzer, H.; Ferland, G. J.; Browne, I. W. A. +6 more
We report the first results from a continuing program to investigate the multifrequency spectrophotometric and other properties of a sample of about 50 radio-loud quasars in the redshift range ∼0.3-1.3. Here we present spectrophotometric data of high signal-to-noise ratio (≳20 in the continuum) of the first 31 radio-loud quasars, over the waveleng…
HST Observations of the Ring around SN 1987A
Chevalier, Roger A.; Kirshner, Robert P.; Lundqvist, Peter +1 more
Hubble Space Telescope observations of SN 1987A show that the circumstellar material near the supernova forms a clumpy elliptical ring. We analyze six epochs of images made with the Faint Object Camera imaging the lines of [O III] and Hβ over the interval 1990 August-1993 October, and three epochs of observations with the Planetary Camera in the c…
Hubble Space Telescope Imaging Polarimetry of the Inner Nuclear Region of NGC 1068
Boksenberg, A.; Capetti, A.; Sparks, W. B. +2 more
We present the results of further Hubble Space Telescope (HST) imaging polarimetry of the inner region of NGC 1068 taken with the COSTAR corrected Faint Object Camera (FOC) in the ultraviolet (2400--2700 A). The centro-symmetric polarization pattern revealed by previous HST imaging polarimetry is shown to extend even closer to the illumination sou…
The Heating of Dust in Starburst Galaxies: The Contribution of the Nonionizing Radiation
Heckman, Timothy M.; Calzetti, D.; Storchi-Bergmann, T. +2 more
The IUE UV and optical spectra and the far-infrared (FIR) IRAS flux densities of a sample of starburst and blue compact galaxies are used to investigate the relationship between dust obscuration and dust emission. The amount of dust obscuration at UV wavelengths correlates with the FIR- to-blue ratio; and an analysis of the correlation indicates t…
Interstellar MG II Absorption Lines from Low-Redshift Galaxies
Bowen, David V.; Pettini, Max; Blades, J. Chris
We have used the GHRS aboard HST to search for interstellar Mg II 2796, 2803 absorption from the disks and halos of 17 low-redshift galaxies, using as probes QSOs and extragalactic supernovae whose sight lines pass close to, or through, intervening galaxies. The galaxies studied are of diverse morphological type, reside in different environments, …
The Polarized Spectrum of the Fe II-rich Broad Absorption Line QSO IRAS 07598+6508
Hines, Dean C.; Wills, Beverley J.
We present IUE spectrophotometry and optical spectropolarimetry of the ultraluminous, extreme Fe II--emitting QSO IRAS 07598+6508. We find broad absorption troughs from high- and low-ionization species, showing that this object is a member of the class of rare low-ionization broad absorption line (BAL) QSOs. Compared with non-BAL QSOs, the spectra…
Performance and Preliminary Calibration of the Hopkins Ultraviolet Telescope on the Astro-2 Mission
Blair, William P.; Kriss, Gerard A.; Davidsen, Arthur F. +4 more
An improved version of the Hopkins Ultraviolet Telescope (HUT) made its second flight on the Astro-2 mission aboard the Space Shuttle Endeavour from 1995 March 2--18. The longer mission duration and greatly improved pointing stability relative to Astro-1 made possible 385 observations of 265 celestial targets at far-ultraviolet wavelengths. Observ…
The Polarization and Ultraviolet Spectrum of Markarian 231
Schmidt, Gary D.; Smith, Paul S.; Allen, Richard G. +1 more
Ultraviolet spectropolarimetry acquired with the Hubble Space Telescope of the peculiar Seyfert galaxy Mrk 231 is combined with new high-quality ground-based measurements to provide the first, nearly complete, record of its linear polarization from 1575 to 7900 A. The accompanying ultraviolet spectrum portrays the heavily extinguished emission-lin…
Spectroscopic Identification of Probable Cataclysmic Variables in the Globular Cluster NGC 6397
Cohn, H. N.; Lugger, P. M.; Cool, A. M. +3 more
The existence of compact binaries in dense clusters is of considerable interest for testing theories of binary production and evolution, as well as the dynamical evolution and survival of the clusters in which they reside. Here, using the newly repaired Hubble Space Telescope to observe the collapsed core of the nearby globular cluster NGC 6397, w…