Jeffrey A. Munn

Max Planck Institute for Astronomy, Heidelburg, Baden-Württemberg, Germany

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Publications (181)692.77 Total impact

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    ABSTRACT: A new proper motion catalog is presented, combining the Sloan Digital Sky Survey (SDSS) with second epoch observations in the r band within a portion of the SDSS imaging footprint. The new observations were obtained with the 90prime camera on the Steward Observatory Bok 90 inch telescope, and the Array Camera on the U.S. Naval Observatory, Flagstaff Station, 1.3 meter telescope. The catalog covers 1098 square degrees to r = 22.0, an additional 1521 square degrees to r = 20.9, plus a further 488 square degrees of lesser quality data. Statistical errors in the proper motions range from 5 mas/year at the bright end to 15 mas/year at the faint end, for a typical epoch difference of 6 years. Systematic errors are estimated to be roughly 1 mas/year for the Array Camera data, and as much as 2 - 4 mas/year for the 90prime data (though typically less). The catalog also includes a second epoch of r band photometry.
    10/2014;
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    ABSTRACT: A large fraction of white dwarfs (WDs) may host planets in their habitable zones. These planets may provide our best chance to detect bio-markers on a transiting exoplanet, thanks to the diminished contrast ratio between the Earth-sized WD and its Earth-sized planets. The JWST is capable of obtaining the first spectroscopic measurements of such planets, yet there are no known planets around WDs. Here we propose to take advantage of the unique capability of the Kepler spacecraft in the 2-Wheels mode to perform a transit survey that is capable of identifying the first planets in the habitable zone of a WD. We propose to obtain Kepler time-series photometry of 10,000 WDs in the SDSS imaging area to search for planets in the habitable zone. Thanks to the large field of view of Kepler, for the first time in history, a large number of WDs can be observed at the same time, which is essential for discovering transits. Our proposed survey requires a total of 200 days of observing time, and will find up to 100 planets in the WD habitable zone. This survey will maintain Kepler's spirit of searching for habitable Earths, but near new hosts. With few-day observations and minute-cadences per field, it will also open up a completely unexplored discovery space. In addition to planets, this survey is sensitive to pulsating WDs, as well as eclipsing short period stellar and substellar companions. These have important implications for constraining the double WD merger rate and their contribution to Type Ia supernovae and the gravitational wave foreground. Given the relatively low number density of our targets, this program can be combined with other projects that would benefit from high cadence and many-fields observations with Kepler, e.g. a transit survey of a magnitude-limited, complete sample of nearby M dwarfs or asteroseismology of variable stars (e.g. RR Lyrae) in the same fields.
    08/2013;
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    ABSTRACT: The Apache Point Observatory Galactic Evolution Experiment (APOGEE) is a high-resolution infrared spectroscopic survey spanning all Galactic environments (i.e., bulge, disk, and halo), with the principal goal of constraining dynamical and chemical evolution models of the Milky Way. APOGEE takes advantage of the reduced effects of extinction at infrared wavelengths to observe the inner Galaxy and bulge at an unprecedented level of detail. The survey's broad spatial and wavelength coverage enables users of APOGEE data to address numerous Galactic structure and stellar populations issues. In this paper we describe the APOGEE targeting scheme and document its various target classes to provide the necessary background and reference information to analyze samples of APOGEE data with awareness of the imposed selection criteria and resulting sample properties. APOGEE's primary sample consists of ~100,000 red giant stars, selected to minimize observational biases in age and metallicity. We present the methodology and considerations that drive the selection of this sample and evaluate the accuracy, efficiency, and caveats of the selection and sampling algorithms. We also describe additional target classes that contribute to the APOGEE sample, including numerous ancillary science programs, and we outline the targeting data that will be included in the public data releases.
    Proceedings of the International Astronomical Union 08/2013; 5.
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    ABSTRACT: The Sloan Digital Sky Survey (SDSS) has been in operation since 2000 April. This paper presents the tenth public data release (DR10) from its current incarnation, SDSS-III. This data release includes the first spectroscopic data from the Apache Point Observatory Galaxy Evolution Experiment (APOGEE), along with spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS) taken through 2012 July. The APOGEE instrument is a near-infrared R~22,500 300-fiber spectrograph covering 1.514--1.696 microns. The APOGEE survey is studying the chemical abundances and radial velocities of roughly 100,000 red giant star candidates in the bulge, bar, disk, and halo of the Milky Way. DR10 includes 178,397 spectra of 57,454 stars, each typically observed three or more times, from APOGEE. Derived quantities from these spectra (radial velocities, effective temperatures, surface gravities, and metallicities) are also included.DR10 also roughly doubles the number of BOSS spectra over those included in the ninth data release. DR10 includes a total of 1,507,954 BOSS spectra, comprising 927,844 galaxy spectra; 182,009 quasar spectra; and 159,327 stellar spectra, selected over 6373.2 square degrees.
    07/2013;
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    ABSTRACT: The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS). This ninth data release (DR9) of the SDSS project includes 535,995 new galaxy spectra (median z=0.52), 102,100 new quasar spectra (median z=2.32), and 90,897 new stellar spectra, along with the data presented in previous data releases. These spectra were obtained with the new BOSS spectrograph and were taken between 2009 December and 2011 July. In addition, the stellar parameters pipeline, which determines radial velocities, surface temperatures, surface gravities, and metallicities of stars, has been updated and refined with improvements in temperature estimates for stars with T_eff<5000 K and in metallicity estimates for stars with [Fe/H]>-0.5. DR9 includes new stellar parameters for all stars presented in DR8, including stars from SDSS-I and II, as well as those observed as part of the SDSS-III Sloan Extension for Galactic Understanding and Exploration-2 (SEGUE-2). The astrometry error introduced in the DR8 imaging catalogs has been corrected in the DR9 data products. The next data release for SDSS-III will be in Summer 2013, which will present the first data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) along with another year of data from BOSS, followed by the final SDSS-III data release in December 2014.
    The Astrophysical Journal Supplement Series 07/2012; 203(2). · 16.24 Impact Factor
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    ABSTRACT: The USNO Infrared astrometry program has been in a suspended state since a June 2006 cryogenic accident with our imaging camera. We describe the current status of bringing the program back to full operation. We expect to re-start an expanded astrometric program in the near future and present our initial list of targets. This will also provide an opportunity for the community to suggest potential cool, low-mass targets which are in need of high quality parallaxes and proper motions. We earlier published preliminary astrometric results for 40 L and T dwarf fields based on the first two years of observations [Vrba et al., AJ, 127, 2948 (2004)]. Those initial objects plus an additional 19 fields added later comprise a total of one M dwarf, 28 L dwarfs, and 39 T dwarfs, including objects in binary systems. Final parallaxes and proper motions for these objects will be published later this year. The additional approximately four years of observations for the original 40 objects improve the mean parallax errors orginially reported from 4.31 mas to 1.73 mas, with the best at 0.64 mas, and the mean proper motion errors from 6.56 mas/yr to 1.09 mas/yr.
    Journal of the American Association of Variable Star Observers (JAAVSO). 06/2012;
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    ABSTRACT: Preliminary analyses of ten brown dwarfs observed by the U.S. Naval Observatory infrared parallax program show no indication of astrometric perturbations due to low mass companions. The data were collected using ASTROCAM on the 1.55-m Strand Astrometric Reflector from 2000 September through 2006 June over periods from 2.0 to 5.8 years. After our standard solution for parallax and proper motion, the residuals were subjected to a time-series analysis using the Lomb-Scargle periodogram method. The multiplicity fraction for brown dwarfs constrains theories of brown dwarf formation and evolution. Binary systems, especially those that straddle the transition between L and T spectral types, are also significant tests of atmospheric models. In addition, the identification of companions enables the eventual measurement of the associated masses. This search for astrometric companions is an extension of the initial infrared parallax program. When finalized, the trigonometric parallaxes for these brown dwarfs will provide accurate distances for use in determining their luminosities and temperatures. The brown dwarfs in this subsample have spectral types in the mid-L through late-T ranges. None are known binaries. Preliminary parallaxes place them within 42 pc; half of these are probable members of the Solar Neighborhood because they lie within 25 pc, including two within 10 pc. These substellar objects are located north of -25° Dec. and lie between 9h and 19h in R.A. The brown dwarfs evaluated are 2MASS J09373487+2931409, 2MASS J09393548-2448279, 2MASSW J1047539+212423, 2MASS J11145133-2618235, 2MASS J12171110-0311131, 2MASS J12373919+6526148, 2MASS J15031961+2525196, 2MASS J15232263+3014562, 2MASS J16322911+1904407, and 2MASS J18410861+3117279. Analyses of another 10 brown dwarfs was presented earlier and the analyses of 29 more brown dwarfs are planned.
    05/2012;
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    ABSTRACT: Carollo et al. have recently resolved the stellar population of the Milky Way halo into at least two distinct components, an inner halo and an outer halo. This result has been criticized by Schönrich et al., who claim that the retrograde signature associated with the outer halo is due to the adoption of faulty distances. We refute this claim, and demonstrate that the Schönrich et al. photometric distances are themselves flawed because they adopted an incorrect main-sequence absolute magnitude relationship from the work of Ivezić et al. When compared to the recommended relation from Ivezić et al., which is tied to a Milky Way globular cluster distance scale and accounts for age and metallicity effects, the relation adopted by Schönrich et al. yields up to 18% shorter distances for stars near the main-sequence turnoff (TO). Use of the correct relationship yields agreement between the distances assigned by Carollo et al. and Ivezić et al. for low-metallicity dwarfs to within 6%-10%. Schönrich et al. also point out that intermediate-gravity stars (3.5 ≤log g < 4.0) with colors redder than the TO region are likely misclassified, with which we concur. We implement a new procedure to reassign luminosity classifications for the TO stars that require it. New derivations of the rotational behavior demonstrate that the retrograde signature and high velocity dispersion of the outer-halo population remain. We summarize additional lines of evidence for a dual halo, including a test of the retrograde signature based on proper motions alone, and conclude that the preponderance of evidence strongly rejects the single-halo interpretation.
    The Astrophysical Journal 01/2012; 746(1):34. · 6.73 Impact Factor
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    ABSTRACT: Preliminary analyses of ten brown dwarfs observed by the U.S. Naval Observatory infrared parallax program show no indication of astrometric perturbations due to low mass companions. The data were collected using ASTROCAM on the 1.55-m Strand Astrometric Reflector from 2000 September through 2006 April over periods from 3.0 to 5.4 years. After our standard solution for parallax and proper motion, the residuals were subjected to a time-series analysis using the Lomb-Scargle periodogram method. The multiplicity fraction for brown dwarfs constrains theories of brown dwarf formation and evolution. Binary systems, especially those that straddle the transition between L and T spectral types, are also significant tests of atmospheric models. In addition, the identification of companions would have enabled the eventual measurement of the associated masses. This search for astrometric companions is an extension of the initial infrared parallax program. When finalized, the trigonometric parallaxes for these brown dwarfs will provide accurate distances for use in determining their luminosities and temperatures. The brown dwarfs in this subsample have spectral types in the late L and mid- to late-T ranges, including one L subdwarf. None are known binaries. Preliminary parallaxes place them within 30 pc; half of these are probable members of the Solar Neighborhood because they lie within 25 pc, including two within 10 pc. These substellar objects are located north of -25° Dec. and lie between 0h and 9h in R.A. The brown dwarfs evaluated are 2MASS J00303013-1450333, 2MASS J02431371-2453298, 2MASS J03284265+2302051, 2MASS J04151954-0935066, 2MASS J05160945-0445499, 2MASS J05325346+8246465, 2MASS J05591914-1404488, 2MASS J07271824+1710012, 2MASS J07554795+2212169, and 2MASS J08251968+2115521. Analyses of 39 more brown dwarfs are planned.
    01/2012;
  • apjs. 08/2011; 195:26.
  • apjs. 08/2011; 195:26.
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    ABSTRACT: The Sloan Digital Sky Survey (SDSS) started a new phase in August 2008, with new instrumentation and new surveys focused on Galactic structure and chemical evolution, measurements of the baryon oscillation feature in the clustering of galaxies and the quasar Ly alpha forest, and a radial velocity search for planets around ~8000 stars. This paper describes the first data release of SDSS-III (and the eighth counting from the beginning of the SDSS). The release includes five-band imaging of roughly 5200 deg^2 in the Southern Galactic Cap, bringing the total footprint of the SDSS imaging to 14,555 deg^2, or over a third of the Celestial Sphere. All the imaging data have been reprocessed with an improved sky-subtraction algorithm and a final, self-consistent photometric recalibration and flat-field determination. This release also includes all data from the second phase of the Sloan Extension for Galactic Understanding and Evolution (SEGUE-2), consisting of spectroscopy of approximately 118,000 stars at both high and low Galactic latitudes. All the more than half a million stellar spectra obtained with the SDSS spectrograph have been reprocessed through an improved stellar parameters pipeline, which has better determination of metallicity for high metallicity stars.
    Astrophysical Journal Supplement Series - ASTROPHYS J SUPPL SER. 01/2011; 193.
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    ABSTRACT: We obtained low-resolution spectroscopy of 98 targets using the 9.2m HET in the queue mode and the Marcario Low Resolution Spectrograph (LRS). Our observations were performed between 2004 October and 2006 July. We obtained JHK photometry of 126 WDs using the Near Infra-Red Imager and Spectrometer (NIRI) on Gemini-North, the 0.8-5.4um medium-resolution spectrograph and imager (SpeX) on the Infrared Telescope Facility (IRTF), and the Wide-Field Camera (WFCAM) on the United Kingdom Infra-Red Telescope (UKIRT). The IRTF observations were obtained on several observing runs between 2004 December and 2006 April. The UKIRT observations (of J0146+1404 and J2239+0018) were performed on UT 2007 September 20. (3 data files).
    VizieR Online Data Catalog. 09/2010;
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    ABSTRACT: We present optical spectroscopy and near-infrared photometry of 126 cool white dwarfs (WDs) in the Sloan Digital Sky Survey (SDSS). Our sample includes high proper motion targets selected using the SDSS and USNO-B astrometry and a dozen previously known ultracool WD candidates. Our optical spectroscopic observations demonstrate that a clean selection of large samples of cool WDs in the SDSS (and the SkyMapper, Pan-STARRS, and the Large Synoptic Survey Telescope data sets) is possible using a reduced proper motion diagram and a tangential velocity cut-off (depending on the proper motion accuracy) of 30 km s–1. Our near-infrared observations reveal eight new stars with significant absorption. We use the optical and near-infrared photometry to perform a detailed model atmosphere analysis. More than 80% of the stars in our sample are consistent with either pure hydrogen or pure helium atmospheres. However, the eight stars with significant infrared absorption and the majority of the previously known ultracool WD candidates are best explained with mixed hydrogen and helium atmosphere models. The age distribution of our sample is consistent with a Galactic disk age of 8 Gyr. A few ultracool WDs may be as old as 12-13 Gyr, but our models have problems matching the spectral energy distributions of these objects. There are only two halo WD candidates in our sample. However, trigonometric parallax observations are required for accurate mass and age determinations and to confirm their membership in the halo.
    The Astrophysical Journal Supplement Series 08/2010; 190(1):77. · 16.24 Impact Factor
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    ABSTRACT: We study Milky Way kinematics using a sample of 18.8 million main-sequence stars with r < 20 and proper-motion measurements derived from Sloan Digital Sky Survey (SDSS) and POSS astrometry, including ~170,000 stars with radial-velocity measurements from the SDSS spectroscopic survey. Distances to stars are determined using a photometric-parallax relation, covering a distance range from ~100 pc to 10 kpc over a quarter of the sky at high Galactic latitudes (|b|>20°). We find that in the region defined by 1 kpc <Z< 5 kpc and 3 kpc <R< 13 kpc, the rotational velocity for disk stars smoothly decreases, and all three components of the velocity dispersion increase, with distance from the Galactic plane. In contrast, the velocity ellipsoid for halo stars is aligned with a spherical coordinate system and appears to be spatially invariant within the probed volume. The velocity distribution of nearby (Z < 1 kpc) K/M stars is complex, and cannot be described by a standard Schwarzschild ellipsoid. For stars in a distance-limited subsample of stars (<100 pc), we detect a multi-modal velocity distribution consistent with that seen by HIPPARCOS. This strong non-Gaussianity significantly affects the measurements of the velocity-ellipsoid tilt and vertex deviation when using the Schwarzschild approximation. We develop and test a simple descriptive model for the overall kinematic behavior that captures these features over most of the probed volume, and can be used to search for substructure in kinematic and metallicity space. We use this model to predict further improvements in kinematic mapping of the Galaxy expected from Gaia and the Large Synoptic Survey Telescope.
    The Astrophysical Journal 05/2010; · 6.73 Impact Factor
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    ABSTRACT: We report the discovery of three nearby old halo white dwarf (WD) candidates in the Sloan Digital Sky Survey (SDSS), including two stars in a common proper motion binary system. These candidates are selected from our 2800deg2 proper motion survey on the Bok and U.S. Naval Observatory Flagstaff Station 1.3 m telescopes, and they display proper motions of 04-05 yr–1. Follow-up MMT spectroscopy and near-infrared photometry demonstrate that all three objects are hydrogen-dominated atmosphere WDs with T eff 3700-4100 K. For average mass WDs, these temperature estimates correspond to cooling ages of 9-10 Gyr, distances of 70-80 pc, and tangential velocities of 140-200 km s–1. Based on the UVW space velocities, we conclude that they most likely belong to the halo. Furthermore, the combined main-sequence and WD cooling ages are 10-11 Gyr. Along with SDSS J1102+4113, they are the oldest field WDs currently known. These three stars represent only a small fraction of the halo WD candidates in our proper motion survey, and they demonstrate that deep imaging surveys like the Pan-STARRS and Large Synoptic Survey Telescope should find many old thick disk and halo WDs that can be used to constrain the age of the Galactic thick disk and halo.
    The Astrophysical Journal Letters 04/2010; 715(1):L21. · 6.35 Impact Factor
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    ABSTRACT: A deep, wide-area proper motion survey is currently underway with the prime focus imaging camera on the Steward Observatory Bok Telescope and the CCD mosaic camera on the United States Naval Observatory Flagstaff Station 1.3m Telescope. The sky footprint of the Sloan Digital Sky Survey (SDSS) is being reimaged in r to a depth of r = 21. These new observations are then matched to the SDSS catalog, yielding proper motions with errors at the faint limit of the survey of roughly 20-30 mas/yr (for a typical epoch difference of 5 years). To date, 2800 square degrees of sky have been imaged. The primary goal of the survey is to generate greatly increased samples of cool disk white dwarfs, as well as thick disk and halo white dwarfs, with which to better constrain the star formation history of the disk, thick disk, and halo.
    01/2010;
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    ABSTRACT: Between 2000 and 2006 NOFS carried out an extensive program of near infrared astrometry of L- and T-dwarfs. Observations were carried out primarily in H-band for L dwarfs and J-band for T dwarfs. The observing cadence was such that, weather permiting, each available program object was observed near the local meridian on multiple nights during each two week bright time observing run. These observations, while primarily designed for astrometric measures, can also been used to study potential brown dwarf variability on time scales ranging from days to several years, which we report here. We present photometric results for 27 L-dwarfs and 28 T-dwarfs (62 total objects including those in binaries). These observations represent approximately 1850 hours of integration time on the 61-inch Kaj Strand Astrometric Reflector. An object was visited on average 62 individual nights with approximately 30 hours of integration time. Only 6 objects were observed for less than 40 nights. Local standards and at least two check stars were set up in each field. The total photometric error budget ranged from less than 0.01 mag for J,H < 14.5 mag, steadily increasing to 0.05 mag for J,H = 17.0 mag. We found no statistically significant variablity for any L- or T-dwarf studied, within the limits of the above error budget. We did find one check star with approximately 0.04 mag variability which appears to be an early M-dwarf, based on its infrared colors. We conclude that L- and T-dwarfs studied do not undergo surface or luminosity changes detectable in the near infrared at the few percent level on time scales of days to several years.
    01/2010;
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    ABSTRACT: This paper describes the Seventh Data Release of the Sloan Digital Sky Survey (SDSS), marking the completion of the original goals of the SDSS and the end of the phase known as SDSS-II. It includes 11,663 deg^2 of imaging data, with most of the ~2000 deg^2 increment over the previous data release lying in regions of low Galactic latitude. The catalog contains five-band photometry for 357 million distinct objects. The survey also includes repeat photometry on a 120° long, 2°.5 wide stripe along the celestial equator in the Southern Galactic Cap, with some regions covered by as many as 90 individual imaging runs. We include a co-addition of the best of these data, going roughly 2 mag fainter than the main survey over 250 deg^2. The survey has completed spectroscopy over 9380 deg^2; the spectroscopy is now complete over a large contiguous area of the Northern Galactic Cap, closing the gap that was present in previous data releases. There are over 1.6 million spectra in total, including 930,000 galaxies, 120,000 quasars, and 460,000 stars. The data release includes improved stellar photometry at low Galactic latitude. The astrometry has all been recalibrated with the second version of the USNO CCD Astrograph Catalog, reducing the rms statistical errors at the bright end to 45 milliarcseconds per coordinate. We further quantify a systematic error in bright galaxy photometry due to poor sky determination; this problem is less severe than previously reported for the majority of galaxies. Finally, we describe a series of improvements to the spectroscopic reductions, including better flat fielding and improved wavelength calibration at the blue end, better processing of objects with extremely strong narrow emission lines, and an improved determination of stellar metallicities.
    The Astrophysical Journal Supplement Series 05/2009; 182(2):543. · 16.24 Impact Factor
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    ABSTRACT: Redshifts, four-band photometry (UBJRFIN), and astrometry are presented for faint galaxies in four widely separated fields. We provide the necessary information to enable well-defined, statistically complete subsamples of faint galaxies to be constructed from the master catalog. The redshift survey is 86% and 71% complete to RF ≤ 18.5 and RF ≤ 19, respectively, yielding 328 galaxies with reliable redshifts to RF ≤ 19, with a median redshift of 0.142. Adding the galaxies from the fainter statistical sample yields a total of 583 reliable redshifts with a median redshift of 0.202. An additional 156 redshifts in the same fields, but not part of the samples defined here, are also given. Of the 739 galaxy redshifts presented, 212 are for galaxies with RF > 20.
    The Astrophysical Journal Supplement Series 01/2009; 109(1):45. · 16.24 Impact Factor

Publication Stats

9k Citations
692.77 Total Impact Points

Institutions

  • 2012
    • Max Planck Institute for Astronomy
      Heidelburg, Baden-Württemberg, Germany
  • 2001–2009
    • University of Chicago
      • • Department of Astronomy and Astrophysics
      • • Kavli Institute for Cosmological Physics
      Chicago, IL, United States
    • University of Michigan
      • Department of Physics
      Ann Arbor, Michigan, United States
    • Johns Hopkins University
      • Department of Physics and Astronomy
      Baltimore, Maryland, United States
  • 2008
    • Harvard-Smithsonian Center for Astrophysics
      Cambridge, Massachusetts, United States
    • The University of Tokyo
      • Institute for Cosmic Ray Research
      Tokyo, Tokyo-to, Japan
  • 2005–2008
    • United States Naval Observatory
      Washington, Maine, United States
    • Pedagogical University of Cracow
      Cracovia, Lesser Poland Voivodeship, Poland
    • Lawrence Berkeley National Laboratory
      • Physics Division
      Berkeley, California, United States
  • 2002–2008
    • Fermi National Accelerator Laboratory (Fermilab)
      Batavia, Illinois, United States
    • Joint Astronomy Centre
      Hilo, Hawaii, United States
  • 2007
    • Australian National University
      • Research School of Astronomy & Astrophysics
      Canberra, Australian Capital Territory, Australia
  • 2001–2006
    • University of Sussex
      • Astronomy Centre
      Brighton, England, United Kingdom
  • 2003–2005
    • Space Telescope Science Institute
      Baltimore, Maryland, United States
  • 2000–2002
    • Princeton University
      • Department of Astrophysical Sciences
      Princeton, New Jersey, United States
  • 1996
    • Michigan State University
      • Department of Physics and Astronomy
      East Lansing, Michigan, United States
  • 1991
    • Carnegie Institution for Science
      Washington, West Virginia, United States