J. A. Smith
A5002306153- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Calibration and Measurement Techniques
- Meteorological Phenomena and Simulations
- Adaptive optics and wavefront sensing
- Flood Risk Assessment and Management
- Atmospheric aerosols and clouds
- Hydrology and Watershed Management Studies
- Tropical and Extratropical Cyclones Research
- Atmospheric Ozone and Climate
- Astro and Planetary Science
- CCD and CMOS Imaging Sensors
- History and Developments in Astronomy
- Atmospheric chemistry and aerosols
- Precipitation Measurement and Analysis
- Spectroscopy and Laser Applications
- Planetary Science and Exploration
- Climate variability and models
- Remote Sensing in Agriculture
- Astrophysical Phenomena and Observations
- Conflict of Laws and Jurisdiction
Austin Peay State University
2015-2024
Ludwig-Maximilians-Universität München
2024
Lancaster University
2024
Aix-Marseille Université
2024
University of Zurich
2024
Stanford University
2024
Oak Ridge National Laboratory
2024
Centre National de la Recherche Scientifique
2024
American Public University System
2024
Royal Devon and Exeter Hospital
2019-2023
The Sloan Digital Sky Survey (SDSS) is an imaging and spectroscopic survey that will eventually cover approximately one-quarter of the celestial sphere collect spectra ≈106 galaxies, 100,000 quasars, 30,000 stars, serendipity targets. In 2001 June, SDSS released to general astronomical community its early data release, roughly 462 deg2 including almost 14 million detected objects 54,008 follow-up spectra. were collected in drift-scan mode five bandpasses (u, g, r, i, z); our 95% completeness...
We present the 158 standard stars that define u'g'r'i'z' photometric system. These form basis for calibration of Sloan Digital Sky Survey. The defining instrument system and filters, observing process, reduction techniques, software used to create stellar network are all described. briefly discuss history star selection derivation a set transformation equations UBVRCIC system, plans future work.
The Sloan Extension for Galactic Understanding and Exploration (SEGUE) Survey obtained ≈240,000 moderate-resolution (R ∼ 1800) spectra from 3900 Å to 9000 of fainter Milky Way stars (14.0 < g 20.3) a wide variety spectral types, both main-sequence evolved objects, with the goal studying kinematics populations our Galaxy its halo. are clustered in 212 regions spaced over three quarters sky. Radial velocity accuracies at 18, degrading 20. For signal-to-noise ratio >10 per resolution element,...
We present five new satellites of the Milky Way discovered in Sloan Digital Sky Survey (SDSS) imaging data, four which were followed up with either Subaru or Isaac Newton Telescopes. They include probable dwarf galaxies—one each constellations Coma Berenices, Canes Venatici, Leo, and Hercules—together one unusually extended globular cluster, Segue 1. provide distances, absolute magnitudes, half-light radii, color-magnitude diagrams for all satellites. The morphological features are generally...
We investigate the extent to which Palomar-Green (PG) Bright Quasar Survey (BQS) is complete and representative of general quasar population by comparing it with imaging spectroscopy from Sloan Digital Sky (SDSS). A comparison SDSS PG photometry both stars quasars reveals need apply a color magnitude recalibration data. Using photometric catalog, we define PG's parent sample objects that are not main-sequence simulate selection this using criteria errors. This simulation shows effective U -...
We identify new structures in the halo of Milky Way Galaxy from positions, colors and magnitudes five million stars detected Sloan Digital Sky Survey. Most these are within 1.26 degrees celestial equator. present color-magnitude diagrams (CMDs) for two previously discovered, tidally disrupted structures. The CMDs turnoff consistent with those Sagittarius dwarf galaxy, as had been predicted. In one direction, we even able to detect a clump red stars, similar that dwarf, spread across 110...
Using effective temperature and metallicity derived from SDSS spectra for ~60,000 F G type main sequence stars (0.2
We discuss measurements of the properties ∼13,000 asteroids detected in 500 deg2 sky Sloan Digital Sky Survey (SDSS) commissioning data. The moving objects are magnitude range 14 < r* 21.5, with a baseline ∼5 minutes, resulting typical velocity errors ∼3%. Extensive tests show that sample is at least 98% complete, contamination rate less than 3%. find size distribution resembles broken power law, independent heliocentric distance: D-2.3 for 0.4 km ≲ D 5 km, and D-4 40 km. As consequence this...
We present 0.6-2.5 μm, R ≳ 400 spectra of 27 cool, low-luminosity stars and substellar objects. Based on these previously published spectra, we develop a preliminary spectral classification system for L T dwarfs. For late types the is based entirely four indices in 1-2.5 μm interval. Two are derived from water absorption bands at 1.15 1.4 latter which shows smooth increase depth through sequences can be used to classify both types. The other two make use methane features H K bands, with...
Abstract We summarize the Sloan Digital Sky Survey data acquisition and processing steps, describe runQA , a pipeline designed for automated quality assessment. In particular, we show how position of stellar locus in color‐color diagrams can be used to estimate accuracy photometric zeropoint calibration better than 0.01 mag 0.03 deg 2 patches. Using this method, that typical errors SDSS imaging are not larger ∼0.01 g r i bands, 0.02 z band, u band (root‐mean‐scatter offsets). (© 2004...
In this Letter, we announce the discovery of a new satellite Milky Way in constellation Bootes at distance 60 kpc. It was found systematic search for stellar overdensities North Galactic Cap using Sloan Digital Sky Survey Data Release 5 (SDSS DR5). The color-magnitude diagram shows well-defined turn-off, red giant branch, and extended horizontal branch. Its absolute magnitude is -5.8, which makes it one faintest galaxies known. half-light radius 220 pc. isodensity contours are elongated have...
Population-based information about cancer occurrence and survival are required to inform clinical practice research; but for most lymphomas data lacking. Set within a socio-demographically representative UK population of nearly 4 million, lymphoma (N=5796) from an established patient cohort. Incidence, (overall relative) prevalence estimates >20 subtypes presented. With few exceptions, males tended be diagnosed at younger ages have significantly (P<0.05) higher incidence rates. Differences...
In this Letter, we announce the discovery of a new dwarf satellite Milky Way, located in constellation Canes Venatici. It was found as stellar overdensity north Galactic cap using Sloan Digital Sky Survey Data Release 5 (SDSS DR5). The satellite's color-magnitude diagram shows well-defined red giant branch well horizontal branch. As judged from tip branch, it lies at distance ~220 kpc. Based on SDSS data, estimate an absolute magnitude MV ~ -7.9, central surface brightness μ0, V 28 mag...
We quantify the variability of faint unresolved optical sources using a catalog based on multiple SDSS imaging observations.The covers stripe 82, which lies along celestial equator in southern Galactic hemisphere (22 h 24 m < J2000:0 04 08 , À1:27 þ1:27 $290 deg 2 ), and contains 34 million photometric observations ugriz system for 748,084 at high latitudes (b À20 ) that were observed least four times each ugri bands (with median 10 obtained over $6 yr).In bandpass we compute various...
We describe the creation, content, and validation of Dark Energy Survey (DES) internal year-one cosmology data set, Y1A1 GOLD, in support upcoming cosmological analyses. The GOLD set is assembled from multiple epochs DES imaging consists calibrated photometric zeropoints, object catalogs, ancillary products - e.g., maps survey depth observing conditions, star-galaxy classification, redshift estimates that are necessary for accurate wide-area catalog ~137 million objects detected coadded...
We describe the Dark Energy Survey (DES) photometric data set assembled from first three years of science operations to support DES Year 3 cosmology analyses, and provide usage notes aimed at broad astrophysics community. Y3 Gold improves on previous releases DES, Y1 Data Release 1 (DES DR1), presenting an expanded curated that incorporates algorithmic developments in image detrending processing, calibration, object classification. comprises nearly 5000 square degrees grizY imaging south...
We present star count data from the Sloan Digital Sky Survey for 5.8 × 105 stars brighter than g' = 21 mag over 279 deg2 in two samples north and south of Galactic plane. Using these high-latitude (49° < |b| 64°) counts we determine Sun's distance midplane to be 27 ± 4 pc scale height old thin disk 330 3 pc. Because photometric accuracy large area sky coverage data, color-magnitude diagram clearly reveals a significant thick-disk population distinct color halo population. The position...
A sample of 4208 objects with magnitude 15 < g* 22 and colors main-sequence stars have been selected from 370 deg2 Sloan Digital Sky Survey (SDSS) commissioning observations. The data is two long, narrow stripes, each an opening angle greater than 60°, at Galactic latitudes 36° |b| 63° on the celestial equator. Relative photometric calibrations good to 2% consistent absolute photometry allows this uniform be treated statistically over large area. An examination sample's distribution shows...
The photometric calibration of the Sloan Digital Sky Survey (SDSS) is a multi-step process which involves data from three different telescopes: 1.0-m telescope at US Naval Observatory (USNO), Flagstaff Station, Arizona (which was used to establish SDSS standard star network); 0.5-m Photometric Telescope (PT) Apache Point (APO), New Mexico calculates nightly extinctions and calibrates secondary patch transfer fields); 2.5-m APO obtains imaging for proper). In this paper, we describe Monitor...
In this Letter, we study a localized stellar overdensity in the constellation of Ursa Major, first identified Sloan Digital Sky Survey (SDSS) data and subsequently followed up with Subaru imaging. Its color-magnitude diagram (CMD) shows well-defined subgiant branch, main sequence, turnoff, from which estimate distance ~30 kpc projected size ~250 × 125 pc2. The CMD suggests composite population some range metallicity and/or age. Based on its extent population, argue that is previously unknown...
We describe a standard star catalog constructed using multiple SDSS photometric observations (at least four per band, with median of 10) in the ugriz system. The includes 1.01 million nonvariable unresolved objects from equatorial stripe 82 (|δJ2000.0| < 1.266°) right ascension range 20h34m-4h00m and corresponding r-band (approximately Johnson V-band) magnitudes 14-22. distributions measurements for individual sources demonstrate that pipeline correctly estimates random errors, which are...