A. C. Becker
A5072420646- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Astrophysics and Star Formation Studies
- Astrophysics and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Adaptive optics and wavefront sensing
- Astro and Planetary Science
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- History and Developments in Astronomy
- Geophysics and Gravity Measurements
- Atmospheric Ozone and Climate
- Impact of Light on Environment and Health
- Planetary Science and Exploration
- Dementia and Cognitive Impairment Research
- Distributed and Parallel Computing Systems
- Cosmology and Gravitation Theories
- Spectroscopy and Laser Applications
- Radio Astronomy Observations and Technology
- Frailty in Older Adults
- Photocathodes and Microchannel Plates
- Neutrino Physics Research
- Chronic Disease Management Strategies
Biogen (United States)
2025
University of Southern California
2023-2024
University of Washington
2010-2019
Amazon (United States)
2019
Ruhr University Bochum
2015-2018
Rosalind Franklin University of Medicine and Science
2018
Large Synoptic Survey Telescope Corporation
2015
École Polytechnique Fédérale de Lausanne
2014
Seattle University
1999-2012
Carnegie Institution for Science
2009
This paper describes the Seventh Data Release of Sloan Digital Sky Survey (SDSS), marking completion original goals SDSS and end phase known as SDSS-II. It includes 11,663 deg2 imaging data, with most ∼2000 increment over previous data release lying in regions low Galactic latitude. The catalog contains five-band photometry for 357 million distinct objects. survey also repeat on a 120° long, 25 wide stripe along celestial equator Southern Cap, some covered by many 90 individual runs. We...
(Abridged) We describe here the most ambitious survey currently planned in optical, Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST have unique capability faint time domain. The design is driven four main themes: probing dark energy matter, taking an inventory Solar System, exploring transient optical sky, mapping Milky Way. wide-field ground-based system sited at Cerro Pach\'{o}n northern Chile. telescope 8.4 m...
This paper describes the Sixth Data Release of Sloan Digital Sky Survey. With this data release, imaging northern Galactic cap is now complete. The survey contains images and parameters roughly 287 million objects over 9583 deg2, including scans a large range latitudes longitudes. also includes 1.27 spectra stars, galaxies, quasars, blank sky (for subtraction) selected 7425 deg2. release much more stellar spectroscopy than was available in previous releases detailed estimates temperatures,...
A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of exciting science opportunities next decade. The Large Synoptic Survey Telescope (LSST) have an effective aperture 6.7 meters and imaging camera field view 9.6 deg^2, be devoted ten-year 20,000 deg^2 south +15 deg. Each pointing imaged 2000 times fifteen second exposures six broad from 0.35 1.1 microns, total point-source depth r~27.5. LSST Science Book describes basic...
We report on our search for microlensing towards the Large Magellanic Cloud (LMC). Analysis of 5.7 years photometry 11.9 million stars in LMC reveals 13 - 17 events. This is significantly more than $\sim$ 2 to 4 events expected from lensing by known stellar populations. The timescales ($\that$) range 34 230 days. estimate optical depth with $2 < \that 400$ days be 1.2 ^{+0.4}_ {-0.3} \ten{-7}$, an additional 20% 30% systematic error. spatial distribution mildly inconsistent LMC/LMC disk...
We present measurements of the Hubble diagram for 103 Type Ia supernovae (SNe) with redshifts 0.04 < z 0.42, discovered during first season (Fall 2005) Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. These data fill in redshift "desert" between low- and high-redshift SN surveys. combine SDSS-II new distance estimates published from ESSENCE survey, Legacy Survey, Space Telescope, a compilation nearby measurements. Combining Baryon Acoustic Oscillations SDSS Luminous Red Galaxy sample...
The MACHO Project is a search for dark matter in the form of massive compact halo objects (MACHOs). Photometric monitoring millions stars Large Magellanic Cloud (LMC), Small (SMC), and Galactic bulge used to gravitational microlensing events caused by these otherwise invisible objects. Analysis first 2.1 yr photometry 8.5 million LMC reveals eight candidate events. This substantially more than number expected (~1.1) from lensing known stellar populations. timescales (t) range 34 145 days. We...
In this paper, we describe the optical imaging data processing pipeline developed for Subaru Telescope's Hyper Suprime-Cam (HSC) instrument. The HSC Pipeline builds on prototype being by Large Synoptic Survey Data Management system, adding customizations HSC, large-scale capabilities, and novel algorithms that have since been reincorporated into LSST codebase. While designed primarily to reduce Strategic Program (SSP) data, it is also recommended reducing general-observer data. includes high...
The Sloan Digital Sky Survey-II (SDSS-II) has embarked on a multi-year project to identify and measure light curves for intermediate-redshift (0.05 < z 0.35) Type Ia supernovae (SNe Ia) using repeated five-band (ugriz) imaging over an area of 300 sq. deg. survey region is stripe 2.5° wide centered the celestial equator in Southern Galactic Cap that been imaged numerous times earlier years, enabling construction deep reference image discovery new objects. Supernova observations are being...
We model the time variability of ∼9000 spectroscopically confirmed quasars in SDSS Stripe 82 as a damped random walk (DRW). Using 2.7 million photometric measurements collected over 10 yr, we confirm results Kelly et al. and Kozłowski that this can explain quasar light curves at an impressive fidelity level (0.01–0.02 mag). The DRW provides simple, fast (O(N) for N data points), powerful statistical description by characteristic timescale (τ) asymptotic rms on long timescales (SF∞). searched...
We provide a quantitative description and statistical interpretation of the optical continuum variability quasars. The Sloan Digital Sky Survey (SDSS) has obtained repeated imaging in five UV-to-IR photometric bands for 33,881 spectroscopically confirmed About 10,000 quasars have an average 60 observations each band over decade along Stripe 82 (S82), whereas remaining ~25,000 2-3 due to scan overlaps. observed time lags span range from day almost 10 years, constrain quasar at rest-frame up 4...
We present EVEREST, an open-source pipeline for removing instrumental noise from K2 light curves. EVEREST employs a variant of pixel level decorrelation (PLD) to remove systematics introduced by the spacecraft's pointing error and Gaussian process (GP) capture astrophysical variability. apply all targets in campaigns 0-7, yielding curves with precision comparable that original Kepler mission stars brighter than $K_p \approx 13$, within factor two fainter targets. perform cross-validation...
We present the use of continuous-time autoregressive moving average (CARMA) models as a method for estimating variability features light curve, and in particular its power spectral density (PSD). CARMA fully account irregular sampling measurement errors, making them valuable quantifying variability, forecasting interpolating curves, variability-based classification. show that PSD model can be expressed sum Lorentzian functions, which makes extremely flexible able to broad range PSDs....
With the emergence of disease-modifying Alzheimer's treatments, timely detection early-stage disease is more important than ever, as treatment will not be indicated for later stages. Contemporary population-level data rates mild cognitive impairment (MCI), stage at which would ideally start, are lacking, and dementia only available subsets Medicare population. We sought to compare documented diagnosis MCI in full population with expected based on a predictive model.
We present UBVRIz lightcurves of the Type Ia SN 1999ee and Ib/c 1999ex, both located in galaxy IC 5179. has an extremely well sampled lightcurve spanning from 10 days before Bmax through 53 after peak. Near maximum we find systematic differences ~0.05 mag photometry measured with two different telescopes, even though is reduced to same local standards around supernova using specific color terms for each instrumental system. use models our bandpasses spectrophotometry derive magnitude...
We describe the implementation and optimization of ESSENCE supernova survey, which we have undertaken to measure equation state parameter dark energy. present a method for optimizing survey exposure times cadence maximize our sensitivity energy w=P/rho c^2 given fixed amount telescope time. For on CTIO 4m telescope, measuring luminosity distances redshifts supernovae at modest (z~0.5 +- 0.2) is optimal determining w. data analysis pipeline based using reliable robust image subtraction find...
The Sloan Digital Sky Survey-II Supernova Survey has identified a large number of new transient sources in 300 deg2 region along the celestial equator during its first two seasons three-season campaign. Multi-band (ugriz) light curves were measured for most sources, which include solar system objects, galactic variable stars, active nuclei, supernovae (SNe), and other astronomical transients. imaging survey is augmented by an extensive spectroscopic follow-up program to identify SNe, measure...
We present extensive u'g'r'i'BVRIYJHKs photometry and optical spectroscopy of the Type Ia supernova (SN) 2005hk. These data reveal that SN 2005hk was nearly identical in its observed properties to 2002cx, which has been called "the most peculiar known supernova." Both supernovae exhibited high‐ionization 1991T–like premaximum spectra, yet low peak luminosities like 1991bg. The spectra 2005hk, expansion velocities were roughly half those typical supernovae. R I light curves both also not...
We present an improved analysis of halo substructure traced by RR Lyrae stars in the SDSS stripe 82 region. With addition SDSS-II data, a revised selection method based on new ugriz light curve templates results sample 483 that is essentially free contamination. The main result from our first study persists: spatial distribution at galactocentric distances 5--100 kpc highly inhomogeneous. At least 20% within 30 Galactic center can be statistically associated with substructure. strong direct...
Characterizing the nature and spatial distribution of lensing objects that produce previously measured microlensing optical depth toward Large Magellanic Cloud (LMC) remains an open problem. We present appraisal ability SuperMACHO Project, a next-generation survey directed LMC, to discriminate between various proposed populations. consider two scenarios: by uniform foreground screen self-lensing LMC stars. have carried out extensive simulations, based upon data obtained during first year...
We present ugriz light curves for 146 spectroscopically-confirmed or spectroscopically-probable Type Ia supernovae (SNe) from the 2005 season of Sloan Digital Sky Survey-II Supernova (SN) survey. The have been constructed using a photometric technique that we call scene modeling, which is described in detail here; major feature SN brightnesses are extracted stack images without spatial resampling convolution image data. This procedure produces accurate photometry along with estimates...
We present details of the construction and characterization coaddition Sloan Digital Sky Survey (SDSS) Stripe 82 ugriz imaging data. This survey consists 275 deg2 repeated scanning by SDSS camera over −50° ⩽ α 60° −125 δ +125 centered on Celestial Equator. Each piece sky has ∼20 runs contributing thus reaches ∼2 mag fainter than single pass data, i.e., to r ∼ 23.5 for galaxies. discuss image processing coaddition, modeling point-spread function (PSF), calibration, production standard...
We use the new Type Ia supernovae discovered by Sloan Digital Sky Survey-II supernova survey, together with additional data sets as well observations of cosmic microwave background and baryon acoustic oscillations to constrain cosmological models. This complements standard cosmology analysis presented Kessler et al. in that we discuss rank a number most popular nonstandard scenarios. When this combined set is analyzed using MLCS2k2 light-curve fitter, find more exotic models for acceleration...