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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…
Polar Plume Anatomy: Results of a Coordinated Observation
Plunkett, S. P.; Thompson, B. J.; Gurman, J. B. +5 more
On 7 and 8 March 1996, the SOHO spacecraft and several other space- and ground-based observatories cooperated in the most comprehensive observation to date of solar polar plumes. Based on simultaneous data from five instruments, we describe the morphology of the plumes observed over the south pole of the Sun during the SOHO observing campaign. Ind…
Time-Distance Helioseismology with the MDI Instrument: Initial Results
Kosovichev, A. G.; Hoeksema, J. T.; Scherrer, P. H. +10 more
In time-distance helioseismology, the travel time of acoustic waves is measured between various points on the solar surface. To some approximation, the waves can be considered to follow ray paths that depend only on a mean solar model, with the curvature of the ray paths being caused by the increasing sound speed with depth below the surface. The …
Microvariability survey with the Hubble Space Telescope Fine Guidance Sensors. Exploring the instrumental properties
Kuschnig, R.; Weiss, W. W.; Gruber, R. +2 more
The suitability of the Hubble Space Telescope (HST) Fine Guidance Sensors (FGS) for a magnitude limited survey of microvariability among guide stars is investigated. The linearity, relative sensitivity, and dead-time constants of the three FGSs are determined, and the photon noise limitation of the FGS photometry is confirmed. The noise spectrum i…
Infrared spectroscopy of interstellar apolar ice analogs
van Dishoeck, E. F.; Tielens, A. G. G. M.; Boogert, A. C. A. +2 more
Apolar ices have been observed in several regions in dense clouds and are likely dominated by molecules such as CO, CO_2 and the infrared inactive molecules O_2 and N_2. Interstellar solid CO has been well characterized by ground-based high resolution measurements. Recent ISO results showed the ubiquitous presence of abundant CO_2 ice and the pres…
Optical-IUE observations of the gamma-ray loud BL Lacertae object S5 0716+714: data and interpretation.
Maraschi, L.; Ghisellini, G.; Pian, E. +14 more
We monitored the BL Lac object S5 0716+714 in the optical band during the period November 1994 - April 1995, which includes the time of a γ-ray observation by the Energetic Gamma Ray Experiment Telescope (EGRET) on February 14-28, 1995. The light curves in the R and B bands show fast fluctuations superimposed on longer timescale variations. The co…
Absolute Magnitude Calibration for the W UMa-Type Systems Based on HIPPARCOS Data
Rucinski, S. M.; Duerbeck, H. W.
Hipparcos parallax data for 40 contact binary stars of the W UMa-type (with epsilon M_V < 0.5) are used to derive a new, (B-V)-based absolute-magnitude calibration of the form M_V = M_V(log P,B-V). The calibration covers the ranges 0.26 < (B-V)_0 < 1.14, 0.24 < P < 1.15 day, and 1.4 < M_V < 6.1; it is based on a solution weigh…
Optical Rotation Curves of Distant Field Galaxies: Sub-L* Systems
Illingworth, Garth D.; Faber, S. M.; Gronwall, Caryl +6 more
Moderate-resolution spectroscopic observations from the Keck 10 m telescope are used to derive internal kinematics for eight faint disk galaxies in the fields flanking the Hubble Deep Field. The spectroscopic data are combined with high-resolution F814W Wide Field Planetary Camera 2 images from the Hubble Space Telescope that provide morphologies,…
Ellipticals with Kinematically Distinct Cores: V - I Color Images with WPFC2
Franx, Marijn; Illingworth, Garth D.; Forbes, Duncan A. +1 more
We have analyzed Hubble Space Telescope WFPC2 F555W and F814W (i.e., V and I) images for 15 elliptical galaxies with kinematically distinct cores. For each of them, we have derived surface brightness and isophotal parameter profiles in the two bands, color maps, and radial profiles in V - I. Most galaxies show patchy dust absorption close to their…
HST observations of blue Straggler stars in the core of the globular cluster M 3.
Burgarella, D.; Cacciari, C.; Buonanno, R. +7 more
The core of the Galactic Globular Cluster M 3 (NGC 5272) has been observed with the WFPC2 through the filters F255W, F336W, F555W, and F814W. Using these observations along with a thorough reanalysis of earlier catalogs, we have produced a catalog of blue straggler stars (BSS) spanning the cluster. Earlier studies and the fainter part of our sampl…