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- Astrophysics (1)
- Clusters (1)
- Cosmic microwave background (1)
- Cosmology (1)
- E/B decomposition (1)
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- Fossils -- Morphology (1)
- Galaxies (1)
- Large-scale structure of the universe (1)
- Life on other planets (1)
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- Observations (1)
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- Phase retrieval (1)
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- SIBOA (1)
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- Trace fossils -- Biosignatures (1)
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Articles 1 - 5 of 5
Full-Text Articles in Astrophysics and Astronomy
Morphological Biosignatures And The Search For Life On Mars, Sherry L. Cady, Jack D. Farmer, John P. Grotzinger, J. William Schopf, Andrew Steele
Morphological Biosignatures And The Search For Life On Mars, Sherry L. Cady, Jack D. Farmer, John P. Grotzinger, J. William Schopf, Andrew Steele
Geology Faculty Publications and Presentations
This report provides a rationale for the advances in instrumentation and understanding needed to assess claims of ancient and extraterrestrial life made on the basis of morphological biosignatures. Morphological biosignatures consist of bona fide microbial fossils as well as microbially influenced sedimentary structures. To be recognized as evidence of life, microbial fossils must contain chemical and structural attributes uniquely indicative of microbial cells or cellular or extracellular processes. When combined with various research strategies, high-resolution instruments can reveal such attributes and elucidate how morphological fossils form and become altered, thereby improving the ability to recognize them in the geological record …
Redshift-Distance Survey Of Early-Type Galaxies: Circular-Aperture Photometry, M. V. Alonso, M. Bernardi, L. N. Da Costa, G. Wegner
Redshift-Distance Survey Of Early-Type Galaxies: Circular-Aperture Photometry, M. V. Alonso, M. Bernardi, L. N. Da Costa, G. Wegner
Dartmouth Scholarship
We present R -band CCD photometry for 1332 early-type galaxies, observed as part of the ENEAR survey of peculiar motions using early-type galaxies in the nearby universe. Circular apertures are used to trace the surface brightness profiles, which are then fitted by a two-component bulge-disk model. From the fits, we obtain the structural parameters required to estimate galaxy distances using the Dn - and fundamental plane relations. We find that about 12% of the galaxies are well represented by a pure r1/4 law, while 87% are best fitted by a two-component model. There are 356 repeated observations of 257 galaxies …
An Efficient Targeting Strategy For Multiobject Spectrograph Surveys: The Sloan Digital Sky Survey “Tiling” Algorithm, Michael R. Blanton, Huan Lin, Robert H. Lupton, F. Miller Maley, Neal Young
An Efficient Targeting Strategy For Multiobject Spectrograph Surveys: The Sloan Digital Sky Survey “Tiling” Algorithm, Michael R. Blanton, Huan Lin, Robert H. Lupton, F. Miller Maley, Neal Young
Dartmouth Scholarship
Large surveys using multiobject spectrographs require automated methods for deciding how to efficiently point observations and how to assign targets to each pointing. The Sloan Digital Sky Survey (SDSS) will observe around 106 spectra from targets distributed over an area of about 10,000 deg2 , using a multiobject fiber spectrograph that can simultaneously observe 640 objects in a circular field of view (referred to as a ‘‘ tile ’’) 1= 49 in radius. No two fibers can be placed closer than 5500 during the same observation; multiple targets closer than this distance are said to ‘‘ collide.’’ We present here …
E/B Decomposition Of Finite Pixelized Cmb Maps, Emory F. Bunn, Matias Zaldarriaga, Max Tegmark, Angelica De Oliveira-Costa
E/B Decomposition Of Finite Pixelized Cmb Maps, Emory F. Bunn, Matias Zaldarriaga, Max Tegmark, Angelica De Oliveira-Costa
Physics Faculty Publications
Separation of the E and B components of a microwave background polarization map or a weak lensing map is an essential step in extracting science from it, but when the map covers only part of the sky and/or is pixelized, this decomposition cannot be done perfectly. We present a method for decomposing an arbitrary sky map into a sum of three orthogonal components that we term ‘‘pure E,’’ ‘‘pure B,’’ and ‘‘ambiguous.’’ The fluctuations in the pure E and B maps are due only to the E and B power spectra, respectively, whereas the source of those in …
Phase Retrieval Using A Genetic Algorithm On The Systematic Image-Based Optical Alignment Test Bed, Jaime R. Taylor
Phase Retrieval Using A Genetic Algorithm On The Systematic Image-Based Optical Alignment Test Bed, Jaime R. Taylor
Physics Faculty Research
NASA’s Marshall Space Flight Center’s Systematic Image-Based Optical Alignment (SIBOA) Testbed was developed to test phase retrieval algorithms and hardware techniques. Individuals working with the facility developed the idea of implementing phase retrieval by breaking the determination of the tip/tilt of each mirror apart from the piston motion (or translation) of each mirror. Presented in this report is an algorithm that determines the optimal phase correction associated only with the piston motion of the mirrors.