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Origin of the Marsden and Kracht Groups of Sunskirting Comets. I. Association with Comet 96P/Machholz and Its Interplanetary Complex
Sekanina, Zdenek; Chodas, Paul W.
Of the three major groups of comets approaching the Sun to between 6 and 12 solar radii and discovered with the coronagraphs on board SOHO, we investigate the Marsden and Kracht groups. We call these comets ``sunskirters'' to distinguish them from the Kreutz system sungrazers. Our objective is to understand the origin, history, and orbital evoluti…
A Solar Minimum Irradiance Spectrum for Wavelengths below 1200 Å
Warren, Harry P.
NRLEUV represents an independent approach to modeling the Sun's EUV irradiance and its variability. Our model utilizes differential emission measure distributions derived from spatially and spectrally resolved solar observations, full-disk solar images, and a database of atomic physics parameters to calculate the solar EUV irradiance. In this pape…
A Photometric Redshift Galaxy Catalog from the Red-Sequence Cluster Survey
Gladders, M. D.; Yee, H. K. C.; Hsieh, B. C. +1 more
The Red-Sequence Cluster Survey (RCS) provides a large and deep photometric catalog of galaxies in the z' and Rc bands for 90 deg2 of sky, and supplemental V and B data have been obtained for 33.6 deg2. We compile a photometric redshift catalog from these four-band data by utilizing the empirical quadrat…
The ACS Virgo Cluster Survey. IV. Data Reduction Procedures for Surface Brightness Fluctuation Measurements with the Advanced Camera for Surveys
Jordán, Andrés; Tonry, John L.; Côté, Patrick +7 more
The Advanced Camera for Surveys (ACS) Virgo Cluster Survey is a large program to image 100 early-type Virgo galaxies using the F475W and F850LP bandpasses of the Wide Field Channel of the ACS instrument on the Hubble Space Telescope (HST). The scientific goals of this survey include an exploration of the three-dimensional structure of the Virgo Cl…
Atomic and Molecular Gas in Colliding Galaxy Systems. I. The Data
Yun, Min S.; Iono, Daisuke; Ho, Paul T. P.
We present H I and CO (1-0) interferometric observations of 10 comparable-mass interacting systems obtained at the Very Large Array (VLA) and the Owens Valley Radio Observatory (OVRO) millimeter array. The primary intent of this study is to investigate the response of cold gas during the early stages of collision of massive disk galaxies. The samp…
X-Ray Emission from Orion Nebula Cluster Stars with Circumstellar Disks and Jets
Bally, John; Feigelson, Eric D.; Kastner, Joel H. +5 more
We investigate the X-ray and near-infrared emission properties of a sample of pre-main-sequence (PMS) stellar systems in the Orion Nebula Cluster (ONC) that display evidence for circumstellar disks (``proplyds'') and optical jets in Hubble Space Telescope (HST) imaging. Our study uses X-ray data acquired during Chandra Orion Ultradeep Program (COU…
Highly Ionized Gas in the Galactic Halo and the High-Velocity Clouds toward PG 1116+215
Tripp, Todd M.; Sembach, Kenneth R.; Savage, Blair D. +1 more
We have obtained high-resolution Far Ultraviolet Spectroscopic Explorer (FUSE) and Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) echelle observations of the quasar PG 1116+215 (zem=0.1765, l=223.36d, b=+68.21d). The semicontinuous coverage of the ultraviolet spectrum over the wavelength range 916-2800 Å provid…
Time-Distance Helioseismology: Inversion of Noisy Correlated Data
Kosovichev, A. G.; Birch, A. C.; Gizon, L. +2 more
In time-distance helioseismology most inversion procedures ignore the correlations in the data errors. Here we simulate the travel-time perturbations of wavepackets that result from known distributions of sound speed inhomogeneities. The forward and inverse problems are carried out using recently developed Born approximation sensitivity kernels. A…
Magnetic Fields from SOHO MDI Converted to the Mount Wilson 150 Foot Solar Tower Scale
Ulrich, Roger K.; Tran, Tham; Bertello, Luca +1 more
In order to permit the construction of long-duration time series dependent on the Sun's magnetic field, this paper presents a detailed cross-correlation between sets of simultaneous magnetograms from the Mount Wilson Observatory (MWO) and the Michelson Doppler Imager (MDI) aboard the SOHO spacecraft. The MWO 150 foot (45.72 m) solar tower telescop…
The Ultraviolet Spectrum of η Carinae: Investigation of the Ejecta Absorption
Gull, T. R.; Nielsen, K. E.; Vieira Kober, G.
We have investigated the far- through mid-UV (1150-2360 Å) spectrum of η Carinae during the late stages of its broad maximum using the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) moderate dispersion echelle modes. The η Car spectrum is a mixture of absorption and emission lines from the surrounding nebula superimposed …