A5015617862- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Spectroscopy and Laser Applications
- Solar and Space Plasma Dynamics
- Gamma-ray bursts and supernovae
- Geophysics and Gravity Measurements
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Crustacean biology and ecology
- Scientific Research and Discoveries
- Atmospheric Ozone and Climate
- Astrophysics and Cosmic Phenomena
- History and Developments in Astronomy
- Planetary Science and Exploration
- Atomic and Molecular Physics
- Atmospheric and Environmental Gas Dynamics
- Marine and environmental studies
- Impact of Light on Environment and Health
- Calibration and Measurement Techniques
- Photocathodes and Microchannel Plates
- Particle accelerators and beam dynamics
Trinity University
2006-2016
University of Michigan–Ann Arbor
1985-2008
Universidad Nacional Autónoma de México
2003
University of Kentucky
1996
Institute of Astronomy
1991
University of Washington
1991
University of Arizona
1991
Carnegie Observatories
1991
Ann Arbor Center for Independent Living
1991
Michigan United
1979
view Abstract Citations (302) References (13) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Steps toward Determination of the Size and Structure Broad-Line Region in Active Galactic Nuclei. II. an Intensive Study NGC 5548 at Optical Wavelengths Peterson, B. M. ; Balonek, T. J. Barker, E. S. Bechtold, Bertram, R. Bochkarev, N. G. Bolte, Bond, D. Boroson, A. Carini, Carone, Christensen, Clements, Cochran, L. Cohen, Crampton, Dietrich, Elvis, Ferguson,...
An 8 month monitoring campaign on the Seyfert 1 galaxy Fairall 9 has been conducted with 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 results this are more ambiguous than those previous campaigns lower luminosity sources, we find general agreement earlier results: (1) there is no measurable lag between ultraviolet continuum bands, (2) measured...
From 1996 June 10 to July 29, the International Ultraviolet Explorer monitored Seyfert 1 galaxy NGC 7469 continuously in an attempt measure time delays between continuum and emission-line fluxes. delays, one can estimate size of region dominating production UV emission lines this source. We find strong respond variations with about 23-31 for Lyα, 27 C IV λ1549, 19-24 N V λ1240, 17-18 Si λ1400, 07-10 He II λ1640. The most remarkable result, however, is detection apparent different bands. With...
view Abstract Citations (164) References (53) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Steps toward Determination of the Size and Structure Broad-Line Region in Active Galactic Nuclei. V. Variability Ultraviolet Continuum Emission Lines NGC 3783 Reichert, G. A. ; Rodriguez-Pascual, P. M. Alloin, D. Clavel, J. Crenshaw, Kriss, Krolik, H. Malkan, Netzer, Peterson, B. Wamsteker, W. Altamore, Altieri, Anderson, K. S. Blackwell, H., Jr. Boisson, C. Brosch,...
view Abstract Citations (113) References (13) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Curtis Schmidt - thin prism survey for extragalactic emission-line objects. University of Michigan List I. MacAlpine, G. M. ; Smith, S. B. Lewis, D. W. A compilation descriptions and positions, along with finding charts, is presented 100 or otherwise interesting They were detected by using the 61 cm aperture telescope in combination a objective at Cerro Tololo...
Three-dimensional spatial models of the line-emitting gas in Crab Nebula, Cassiopeia A, and nova remnant GK Persei have been developed from imaging spectroscopy taken with Goddard Fabry- Perot Imager mounted on McGraw-Hill 1.3 m Hiltner 2.4 telescopes Michigan-Dartmouth-MIT Observatory. The model Nebula [O III] λ5007 emission reveals thin, annular morphology "high-helium torus," association this torus other bright filament loops north-south bipolar asymmetry shell, structure filamentary...
As part of an extensive multiwavelength monitoring campaign, the International Ultraviolet Explorer satellite was used to observe broad-line radio galaxy 3C 390.3 during period 1994 December 31-1996 March 5. Spectra were obtained every 6-10 days. The UV continuum varied by a factor 7 through while broad emission lines factors 2-5. Unlike previously monitored Seyfert 1 galaxies, in which X-ray generally varies with larger amplitude than UV, light curve is similar both and shape observed...
We present the results of an intensive ultraviolet monitoring campaign on Seyfert 1 galaxy NGC 4151, as part effort to study its short time-scale variability over a broad range in wavelength. The nucleus 4151 was observed continuously with {\it International Ultraviolet Explorer} (IUE) for 9.3 days, yielding pair LWP and SWP spectra every $\sim$70 minutes, during four-hour periods 4 days prior 5 after continuous period. sampling frequency observations is order magnitude higher than that any...
view Abstract Citations (94) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Steps toward Determination of the Size and Structure Broad-Line Region in Active Galactic Nuclei. IV. Intensity Variations Optical Emission Lines NGC 5548 Dietrich, M. ; Kollatschny, W. Peterson, B. Bechtold, J. Bertram, R. Bochkarev, N. G. Boroson, T. A. Carone, E. Elvis, Filippenko, V. Gaskell, C. Huchra, P. Hutchings, Koratkar, Korista, K. Lame, Laor, MacAlpine,...
view Abstract Citations (104) References (53) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Observations of a Complete Sample Emission-Line Galaxies. II. Properties the UM Survey Galaxies Salzer, John J. ; MacAlpine, Gordon M. Boroson, Todd A. We utilize our extensive collection imaging and spectroscopic data to investigate properties emission-line galaxies (ELGs) found in Lists IV V University Michigan (UM) objective-prism survey. The majority ELGs this...
view Abstract Citations (103) References (66) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Observations of a Complete Sample Emission-Line Galaxies. I. CCD Imaging and Spectroscopy Galaxies in UM Lists IV V Salzer, John J. ; MacAlpine, Gordon M. Boroson, Todd A. spectroscopic observations complete sample emission-line galaxy (ELG) candidates from the University Michigan objective-prism survey have been obtained order to investigate fully properties...
This is the first paper in a series aimed at selecting ≡1000 QSOs brighter than m<SUB>J</SUB> = 18.5 using machine-scanned direct and objective-prism plates from UK Schmidt Telescope. The plate material scanned Institute of Astronomy's Automated Plate Measuring facility; algorithms select approximately three candidates per square degree as possible QSOs. Follow-up spectroscopy Multiple Mirror Telescope used to classify each candidate. In this initial paper, authors describe scientific...
view Abstract Citations (95) References (11) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Curtis Schmidt-thin prism survey for extragalactic emission-line objects. University of Michigan list IV. MacAlpine, G. M. ; Lewis, D. W. Descriptions, positions, and finding charts are presented 62 apparent galaxies 58 QSO candidates. They were detected optically with a 61-cm-aperture Schmidt telescope in combination thin objective prism. This contains sources to...
This is the fifth and final paper in a series reporting results of program aimed at selecting ~1000 QSOs brighter than B_J_~ 18.75 using machine-scanned direct objective-prism plates from UK Schmidt Telescope. The plate material scanned Automated Plate Measuring facility. candidate list derived number complementary selection algorithms ranging "traditional" criteria, such as presence strong emission features, to criteria designed select objects whose spectra cannot be classified normal...
Results from the second observing season, in which 156 QSOs have been found three equatorial UK Schmidt field covering an effective area of 85 sq deg, are described. Of 31 listed Hewitt-Burbidge catalog, 22 identified; one remaining nine has overlapping objective prism spectrum and rest were fainter than derived magnitude limit at epoch direct plate. Coordinates, magnitudes, redshifts, spectra moderate resolution signal-to-noise ratio presented for all 12 additional extragalactic objects.
We present results of new photoionization calculations for investigating gaseous regions that represent potentially expected stages nuclear processing in the Crab Nebula supernova remnant. In addition to gas resulting from CNO-processing and oxygen-burning, as previously reported, a large component nebula appears be carbon-rich. These suggest precursor star had an initial mass 9.5 solar masses or more.
Photometry and kinematics are presented for a sample of objective prism selected carbon stars toward the north south Galactic poles. Distances determined by fitting infrared colors to giant branch. If these like seen in dwarf spheroidal galaxies, median distance is 28 kpc. they more found recently bulge, may be only half as distant. The surface density function remarkably consistent with an R exp 1/4 profile halo. This can traced about 15 scale radii fills volume similar that occupied...
This is the third paper in a series aimed at selecting ~1000 QSOs brighter than B_J_~18.7 using machine-scanned direct and objective-prism plates from UK Schmidt Telescope. The plate material scanned Automated Plate Measuring facility. candidate list derived number of complementary selection algorithms ranging "traditional" criteria, such as presence strong emission features, to criteria designed select objects whose spectra cannot be classified normal stars, although they may possess no...
view Abstract Citations (72) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Crab Nebula. II - A photoionization model analysis for the filaments Henry, R. B. C. ; MacAlpine, G. M. interpretation of recent Nebula filament spectrophotometric observations in light detailed models, indicates that large measured filament-to-filament variations He I 5876 A/H-beta ratio are probably caused by relative abundance differences. Preliminary evidence...
view Abstract Citations (59) References (49) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Geometry, Composition, and Mass of the Crab Nebula MacAlpine, Gordon M. ; McGaugh, Stacy S. Mazzarella, Joseph Uomoto, Alan Interference filter images long-slit spectroscopy are presented which show that much brighter filamentary gas in is involved large structures consisting a nearly pure helium band or torus across neutron star bipolar, helium-rich lobes. It...
view Abstract Citations (79) References (34) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Discovery and spectrophotometry of high-redshift quasars. MacAlpine, G. M. ; Feldman, F. R. The discovery 30 quasars that were detected by the Curtis Schmidt technique is reported, along with spectrophotometric observations objects. Spectrophotometric 23 other are also discussed. redshift distribution for 35 analyzed, ten unusual examined, Lyman limit described 17...
view Abstract Citations (58) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spectrophotometry of Michigan-Tololo quasars. Lewis, D. W. ; MacAlpine, G. M. Weedman, The sample quasars is discussed using observational data for 48% this sample. Emission-line quasar characteristics are confirmed 80% the objects observed, including at least four new with spectral features indicative 'supernova-like' outflow. Approximately 73% redshifts predicted...
view Abstract Citations (76) References (10) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Curtis Schmidt-thin prism survey for extragalactic emission-line objects: University of Michigan List III. MacAlpine, G. M. ; Lewis, D. W. Smith, S. B. Descriptions, positions, and finding charts are presented 100 objects possible QSOs. Also included is one apparent galactic nova. They were detected optically with the 61 cm aperture Schmidt telescope in combination a...
Images of the Crab Nebula have been obtained through custom interference filters that transmit emission from expanding supernova remnant in He ii λ4686, Hβ, i λ5876, [O i] λλ6300, 6364, [N ii] λλ6548, 6583, [S λλ6716, 6731, iii] λ9069, and [C λλ9823, 9850. We present both raw flux-calibrated emission-line images. Arrays 19,440 photoionization models, with extensive input abundance ranges, were matched pixel by to calibrated data order derive corresponding element or mass-fraction...