C. G. Tinney

University of New South Wales, Kensington, New South Wales, Australia

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Publications (193)713.7 Total impact

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    ABSTRACT: We report the discovery of two giant planets orbiting the K giant HD 33844 based on radial velocity data from three independent campaigns. The planets move on nearly circular orbits with semimajor axes $a_b=1.60\pm$0.02 AU and $a_c=2.24\pm$0.05 AU, and have minimum masses (m sin $i$) of $M_b=1.96\pm$0.12 Mjup and $M_c=1.76\pm$0.18 Mjup. Detailed N-body dynamical simulations show that the two planets remain on stable orbits for more than $10^6$ years for low eccentricities, and are most likely trapped in a mutual 3:5 mean-motion resonance.
    No preview · Article · Dec 2015 · The Astrophysical Journal
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    ABSTRACT: We use archival HARPS spectra to detect three planets orbiting the M3 dwarf Wolf1061 (GJ 628). We detect a 1.36 Mearth minimum-mass planet with an orbital period P = 4.888d (Wolf1061b), a 4.25 Mearth minimum-mass planet with orbital period P = 17.867d (Wolf1061c), and a likely 5.21 Mearth minimum-mass planet with orbital period P = 67.274d (Wolf1061d). All of the planets are of sufficiently low mass that they may be rocky in nature. The 17.867d planet falls within the habitable zone for Wolf 1061 and the 67.274d planet falls just outside the outer boundary of the habitable zone. There are no signs of activity observed in the bisector spans, cross-correlation full-width-half-maxima, Calcium H & K indices, NaD indices, or H-alpha indices near the planetary periods. We use custom methods to generate a cross-correlation template tailored to the star. The resulting velocities do not suffer the strong annual variation observed in the HARPS DRS velocities. This differential technique should deliver better exploitation of the archival HARPS data for the detection of planets at extremely low amplitudes.
    Preview · Article · Dec 2015
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    ABSTRACT: Planets in highly eccentric orbits form a class of objects not seen within our Solar System. The most extreme case known amongst these objects is the planet orbiting HD 20782, with an orbital period of 597 days and an eccentricity of 0.96. Here we present new data and analysis for this system as part of the Transit Ephemeris Refinement and Monitoring Survey (TERMS). We obtained CHIRON spectra to perform an independent estimation of the fundamental stellar parameters. New radial velocities from AAT and PARAS observations during periastron passage greatly improve the our knowledge of the eccentric nature of the orbit. The combined analysis of our Keplerian orbital and Hipparcos astrometry show that the inclination of the planetary orbit is > 1.25 degrees, ruling out stellar masses for the companion. Our long-term robotic photometry show that the star is extremely stable over long timescales. Photometric monitoring of the star during predicted transit and periastron times using MOST rule out a transit of the planet and reveal evidence of phase variations during periastron. These possible photometric phase variations are likely caused by reflected light from the planet's atmosphere and the dramatic change in star--planet separation surrounding the periastron passage.
    Preview · Article · Nov 2015
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    ABSTRACT: We report a new giant planet orbiting the K giant HD 155233, as well as four stellar-mass companions from the Pan-Pacific Planet Search, a southern hemisphere radial velocity survey for planets orbiting nearby giants and subgiants. We also present updated velocities and a refined orbit for HD 47205b (7 CMa b), the first planet discovered by this survey. HD 155233b has a period of 885$\pm$63 days, eccentricity e=0.03$\pm$0.20, and m sin i=2.0$\pm$0.5 M_jup. The stellar-mass companions range in m sin i from 0.066 M_sun to 0.33 M_sun. Whilst HD 104358B falls slightly below the traditional 0.08 M_sun hydrogen-burning mass limit, and is hence a brown dwarf candidate, we estimate only a 50% a priori probability of a truly substellar mass.
    Preview · Article · Oct 2015 · Monthly Notices of the Royal Astronomical Society
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    ABSTRACT: We report the discovery of KELT-14b and KELT-15b, two hot Jupiters from the KELT-South survey. KELT-14b, an independent discovery of the recently announced WASP-122b, is an inflated Jupiter mass planet that orbits a $\sim5.0^{+0.3}_{-0.7}$ Gyr, $V$ = 11.0, G2 star that is near the main sequence turnoff. The host star, KELT-14 (TYC 7638-981-1), has an inferred mass $M_{*}$=$1.18_{-0.07}^{+0.05}$ M$_{\odot}$ and radius $R_{*}$=$1.37\pm{-0.08}$ R$_{\odot}$, and has T$_{eff}$=$5802_{-92}^{+95}$ K, $\log{g}$ = $4.23_{-0.04}^{+0.05}$ and [Fe/H] = $0.33\pm{-0.09}$. The planet orbits with a period of $1.7100588 \pm 0.0000025$ days ($T_{0}$=2457091.02863$\pm$0.00047) and has a radius R$_{P}$=$1.52_{-0.11}^{+0.12}$ R$_{J}$ and mass M$_{P}$ = $1.196\pm0.072$ M$_{J}$, and the eccentricity is consistent with zero. KELT-15b is another inflated Jupiter mass planet that orbits a $\sim$ $4.6^{+0.5}_{-0.4}$ Gyr, $V$ = 11.2, G0 star (TYC 8146-86-1) that is near the "blue hook" stage of evolution prior to the Hertzsprung gap, and has an inferred mass $M_{*}$=$1.181_{-0.050}^{+0.051}$ M$_{\odot}$ and radius $R_{*}$=$1.48_{-0.04}^{+0.09}$ R$_{\odot}$, and T$_{eff}$=$6003_{-52}^{+56}$ K, $\log{g}$=$4.17_{-0.04}^{+0.02}$ and [Fe/H]=$0.05\pm0.03$. The planet orbits on a period of $3.329441 \pm 0.000016$ days ($T_{0}$ = 2457029.1663$\pm$0.0073) and has a radius R$_{P}$=$1.443_{-0.057}^{+0.11}$ R$_{J}$ and mass M$_{P}$=$0.91_{-0.22}^{+0.21}$ M$_{J}$ and an eccentricity consistent with zero. KELT-14b has the second largest expected emission signal in the K-band for known transiting planets brighter than $K<10.5$. Both KELT-14b and KELT-15b are predicted to have large enough emission signals that their secondary eclipses should be detectable using ground-based observatories.
    No preview · Article · Sep 2015
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    ABSTRACT: We report detections and constraints for the near-infrared Ks band secondary eclipses of seven hot-Jupiters using the IRIS2 infrared camera on the Anglo-Australian Telescope. Eclipses in the Ks band for WASP-18b and WASP-36b have been measured for the first time. We also present new measurements for the eclipses of WASP-4b, WASP-5b, and WASP-46b, as well as upper limits for the eclipse depths of WASP-2b and WASP-76b. In particular, two full eclipses of WASP-46b were observed, allowing us to demonstrate the repeatability of our observations via independent analyses on each eclipse. Significant numbers of eclipse depths for hot-Jupiters have now been measured in both Ks and the four Spitzer IRAC bandpasses. We discuss these measurements in the context of the broad-band colours and brightness temperatures of the hot-Jupiter atmosphere distribution. Specifically, we re-examine the proposed temperature dichotomy between the most irradiated, and mildly irradiated planets. We find no evidence for multiple clusters in the brightness temperature–equilibrium temperature distributions in any of these bandpasses, suggesting a continuous distribution of heat re-emission and circulation characteristics for these planets.
    Full-text · Article · Sep 2015 · Monthly Notices of the Royal Astronomical Society
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    ABSTRACT: Analysis of T dwarfs using model atmospheres has been hampered by the absence of reliable line lists for methane and ammonia. Newly computed high temperature line lists for both of these important molecules are now available, so it is timely to investigate the appearance of the various absorption features in T dwarfs in order to better understand their atmospheres and validate the new line lists. We present high quality R~5000 Gemini/NIFS 1.0-2.4 microns spectra of the T8 standard 2MASS 0415-0935 and the T9 standard UGPS 0722-0540. We use these spectra to identify numerous methane and ammonia features not previously seen and we discuss the implications for our understanding of T dwarf atmospheres. Among our results, we find that ammonia is the dominant opacity source between ~1.233-1.266 microns in UGPS 0722-0540, and we tentatively identify several absorption features in this wavelength range in the T9's spectrum which may be due entirely to ammonia opacity. Our results also suggest that water rather than methane is the dominant opacity source in the red half of the J-band of the T8 dwarf. Water appears to be the main absorber in this wavelength region in the T9 dwarf until ~1.31 microns, when methane starts to dominate.
    Full-text · Article · Mar 2015 · Monthly Notices of the Royal Astronomical Society
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    ABSTRACT: We report the discovery of HATS-13b and HATS-14b, two hot-Jupiter transiting planets discovered by the HATSouth survey. The host stars are quite similar to each other (HATS-13: V = 13.9 mag, M* = 0.96 Msun, R* = 0.89 Rsun, Teff = 5500 K, [Fe/H] = 0.05; HATS-14: V = 13.8 mag, M* = 0.97 Msun, R* = 0.93 Rsun, Teff = 5350 K, [Fe/H] = 0.33) and both the planets orbit around them with a period of roughly 3 days and a separation of roughly 0.04 au. However, even though they are irradiated in a similar way, the physical characteristics of the two planets are very different. HATS-13b, with a mass of Mp = 0.543 MJ and a radius of Rp = 1.212 RJ, appears as an inflated planet, while HATS-14b, having a mass of Mp = 1.071 MJ and a radius of Rp = 1.039 RJ, is only slightly larger in radius than Jupiter.
    Full-text · Article · Mar 2015 · Astronomy and Astrophysics
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    ABSTRACT: We present the discovery of 49 new photometrically classified T dwarfs from the combination of large infrared and optical surveys combined with follow-up Telescopio Nazionale Galileo photometry. We used multiband infrared and optical photometry from the United Kingdom Infrared Telescope and Sloan Digital Sky Surveys to identify possible brown dwarf candidates, which were then confirmed using methane filter photometry. We have defined a new photometric conversion between CH4s − CH4l colour and spectral type for T4–T8 brown dwarfs based on a part of the sample that has been followed up using methane photometry and spectroscopy. Using methane differential photometry as a proxy for spectral type for T dwarfs has proved to be a very efficient technique. Of a subset of 45 methane selected brown dwarfs that were observed spectroscopically, 100 per cent were confirmed as T dwarfs. Future deep imaging surveys will produce large samples of faint brown dwarf candidates, for which spectroscopy will not be feasible. When broad wavelength coverage is unavailable, methane imaging offers a means to efficiently classify candidates from such surveys using just a pair of near-infrared images.
    Full-text · Article · Feb 2015 · Monthly Notices of the Royal Astronomical Society
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    ABSTRACT: Precise radial velocities from the Anglo-Australian Telescope confirm the presence of a rare short-period planet around the K0 giant HD 121056. An independent two-planet solution using the AAT data shows that the inner planet has P=89.1+/-0.1 days, and m sin i=1.35+/-0.17 Mjup. These data also confirm the planetary nature of the outer companion, with m sin i=3.9+/-0.6 Mjup and a=2.96+/-0.16 AU. HD 121056 is the most-evolved star to host a confirmed multiple-planet system, and is a valuable example of a giant star hosting both a short-period and a long-period planet.
    Preview · Article · Dec 2014 · The Astrophysical Journal
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    ABSTRACT: In recent years brown dwarfs have been extended to a new Y-dwarf class with effective temperatures colder than 500K and masses in the range 5-30 Jupiter masses. They fill a crucial gap in observable atmospheric properties between the much colder gas-giant planets of our own Solar System (at around 130K) and both hotter T-type brown dwarfs and the hotter planets that can be imaged orbiting young nearby stars (both with effective temperatures of in the range 1500-1000K). Distance measurements for these objects deliver absolute magnitudes that make critical tests of our understanding of very cool atmospheres. Here we report new distances for nine Y dwarfs and seven very-late T dwarfs. These reveal that Y dwarfs do indeed represent a continuation of the T dwarf sequence to both fainter luminosities and cooler temperatures. They also show that the coolest objects display a large range in absolute magnitude for a given photometric colour. The latest atmospheric models show good agreement with the majority of these Y dwarf absolute magnitudes. This is also the case for WISE0855-0714 the coldest and closest brown dwarf to the Sun, which shows evidence for water ice clouds. However, there are also some outstanding exceptions, which suggest either binarity or the presence of condensate clouds. The former is readily testable with current adaptive optics facilities. The latter would mean that the range of cloudiness in Y dwarfs is substantial with most hosting almost no clouds -- while others have dense clouds making them prime targets for future variability observations to study cloud dynamics.
    Preview · Article · Oct 2014 · The Astrophysical Journal
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    ABSTRACT: We report new Ks-band secondary eclipse observations for the hot-Jupiters WASP-19b and WASP-43b. Using the IRIS2 infrared camera on the Anglo-Australian Telescope (AAT), we measured significant secondary eclipses for both planets, with depths of $0.287_{-0.020}^{+0.020}$ per cent and $0.181_{-0.027}^{+0.027}$ per cent for WASP-19b and WASP-43b, respectively. We compare the observations to atmosphere models from the vstar line-by-line radiative transfer code, and examine the effect of C/O abundance, top layer haze, and metallicities on the observed spectra. We performed a series of signal injection and recovery exercises on the observed light curves to explore the detection thresholds of the AAT+IRIS2 facility. We find that the optimal photometric precision is achieved for targets brighter than Kmag = 9, for which eclipses as shallow as 0.05 per cent are detectable at >5σ significance.
    Full-text · Article · Sep 2014 · Monthly Notices of the Royal Astronomical Society
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    B. C. Addison · C. G. Tinney · D. J. Wright · D. Bayliss
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    ABSTRACT: We have measured the alignment between the orbit of HATS-3b (a recently discovered, slightly inflated Hot Jupiter) and the spin-axis of its host star. Data were obtained using the CYCLOPS2 optical-fiber bundle and its simultaneous calibration system feeding the UCLES spectrograph on the Anglo-Australian Telescope. The sky-projected spin-orbit angle of $\lambda = 3\pm25^{\circ}$ was determined from spectroscopic measurements of Rossiter-McLaughlin effect. This is the first exoplanet discovered through the HATSouth transit survey to have its spin-orbit angle measured. Our results indicate that the orbital plane of HATS-3b is consistent with being aligned to the spin axis of its host star. The low obliquity of the HATS-3 system, which has a relatively hot mid F-type host star, agrees with the general trend observed for Hot Jupiter host stars with effective temperatures $>6250$K to have randomly distributed spin-orbit angles.
    Full-text · Article · Sep 2014 · The Astrophysical Journal
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    ABSTRACT: We present a deep near-infrared image of the newly discovered brown dwarf WISE J085510.83-071442.5 (W0855) using the FourStar imager at Las Campanas Observatory. Our detection of J3=24.8+0.33 -0.53 (J_MKO=25.0+0.33-0.53) at 2.6sigma -- or equivalently an upper limit of J3 > 23.8 (J_MKO > 24.0) at 5sigma makes W0855 the reddest brown dwarf ever categorized (J_MKO - W2 = 10.984+0.33 - 0.53 at 2.6sigma -- or equivalently an upper limit of J_MKO - W2 > 9.984 at 5sigma) and refines its position on color magnitude diagrams. Comparing the new photometry with chemical equilibrium model atmosphere predictions, we demonstrate that W0855 is 4.5sigma from models using a cloudless atmosphere and well reproduced by partly cloudy models (50%) containing sulfide and water ice clouds. Non-equilibrium chemistry or non-solar metallicity may change predictions, however using currently available model approaches, this is the first candidate outside our own solar system to have direct evidence for water clouds.
    Preview · Article · Aug 2014 · The Astrophysical Journal Letters
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    ABSTRACT: We report the detection of GJ 832c, a super-Earth orbiting near the inner edge of the habitable zone of GJ 832, an M dwarf previously known to host a Jupiter analog in a nearly-circular 9.4-year orbit. The combination of precise radial-velocity measurements from three telescopes reveals the presence of a planet with a period of 35.68+/-0.03 days and minimum mass (m sin i) of 5.4+/-1.0 Earth masses. GJ 832c moves on a low-eccentricity orbit (e=0.18+/-0.13) towards the inner edge of the habitable zone. However, given the large mass of the planet, it seems likely that it would possess a massive atmosphere, which may well render the planet inhospitable. Indeed, it is perhaps more likely that GJ 832c is a "super-Venus," featuring significant greenhouse forcing. With an outer giant planet and an interior, potentially rocky planet, the GJ 832 planetary system can be thought of as a miniature version of our own Solar system.
    Full-text · Article · Jun 2014 · The Astrophysical Journal
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    ABSTRACT: We present Keck II laser guide star adaptive optics observations of the brown dwarf WISEP J061135.13?041024.0 showing it is a binary with a component separation of 04. This system is one of the six known resolved binaries in which the magnitude differences between the components show a reversal in sign between the Y/J band and the H/K bands. Deconvolution of the composite spectrum results in a best-fit binary solution with L9 and T1.5 components. We also present a preliminary parallax placing the system at a distance of 21.2 ? 1.3?pc. Using the distance and resolved magnitudes we are able to place WISEP J061135.13?041024.0 AB on a color-absolute magnitude diagram, showing that this system contributes to the well-known "J-band bump" and the components' properties appear similar to other late-type L and early-type T dwarfs. Fitting our data to a set of cloudy atmosphere models suggests the system has an age >1?Gyr with WISE 0611?0410 A having an effective temperature (T eff) of 1275-1325?K and mass of 64-65 M Jup, and WISE 0611?0410 B having T eff?= 1075-1115?K and mass 40-65 M Jup.
    Full-text · Article · May 2014 · The Astronomical Journal
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    ABSTRACT: We present Keck II laser guide star adaptive optics observations of the brown dwarf WISEP J061135.13-041024.0 showing it is a binary with a component separation of 0.4". This system is one of the six known resolved binaries in which the magnitude differences between the components show a reversal in sign between the Y/J band and the H/K bands. Deconvolution of the composite spectrum results in a best fit binary solution with L9 and T1.5 components. We also present a preliminary parallax placing the system at a distance of 21.2+/-1.3 pc. Using the distance and resolved magnitudes we are able to place WISEP J061135.13-041024.0AB on a color-absolute magnitude diagram, showing that this system contributes to the well-known "J-band bump" and the components' properties appear similar to other late-type L and early-type T dwarfs. Fitting our data to a set of cloudy atmosphere models suggests the system has an age >1 Gyr with WISEP J061135.13-041024.0A having an effective temperature (Teff) of 1275-1325 K and mass of 64-65 M_Jup, and WISEP J061135.13-041024.0B having Teff = 1075-1115 K and mass 40-65 M_Jup.
    No preview · Article · Apr 2014
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    Duncan J. Wright · Christopher G. Tinney · Robert A. Wittenmyer
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    ABSTRACT: Detecting the small velocity amplitudes (<= 10 m/s) produced by habitable zone rocky planets around M Dwarfs requires radial velocity precisions of a few m s-1. However, an iodine absorption cell, commonly used as a high precision wavelength reference on non-stabilised spectrographs, is not efficient for very red and faint objects like M Dwarfs. Instead, arc lamps have to be used. With the exception of the ultra-stabilised HARPS spectrograph, achieving ~m s-1 calibration with arc lamps has not been possible because typical spectrographs experience drifts of several hundred m s-1 due to local atmospheric changes in pressure and temperature. We outline and present results from an innovative differential wavelength calibration method that enables ~m s-1 precision from non-stabilised, high-resolution spectrographs. This technique allows the detection of rocky planets with radial velocity amplitudes of a few m s-1.
    Preview · Article · Mar 2014 · Proceedings of the International Astronomical Union
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    ABSTRACT: The discovery of giant planets orbiting close to their host stars was one of the most unexpected results of early exoplanetary science. Astronomers have since found that a significant fraction of these 'Hot Jupiters' move on orbits substantially misaligned with the rotation axis of their host star. We recently reported the measurement of the spin-orbit misalignment for WASP-79b by using data from the 3.9 m Anglo-Australian Telescope. Contemporary models of planetary formation produce planets on nearly coplanar orbits with respect to their host star's equator. We discuss the mechanisms which could drive planets into spin-orbit misalignment. The most commonly proposed being the Kozai mechanism, which requires the presence of a distant, massive companion to the star-planet system. We therefore describe a volume-limited direct-imaging survey of Hot Jupiter systems with measured spin-orbit angles, to search for the presence of stellar companions and test the Kozai hypothesis.
    Full-text · Article · Mar 2014
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    ABSTRACT: We report the discovery of two long-period giant planets from the Anglo-Australian Planet Search. HD 154857c is in a multiple-planet system, while HD 114613b appears to be solitary. HD 114613b has an orbital period P=10.5 years, and a minimum mass m sin i of 0.48 Jupiter masses; HD 154857c has P=9.5 years and m sin i=2.6 Jupiter masses. These new data confirm the planetary nature of the previously unconstrained long-period object in the HD 154857 system. We have performed detailed dynamical stability simulations which show that the HD 154857 two-planet system is stable on timescales of at least 100 million years. These results highlight the continued importance of "legacy" surveys with long observational baselines; these ongoing campaigns are critical for determining the population of Jupiter analogs, and hence of those planetary systems with architectures most like our own Solar system.
    Full-text · Article · Jan 2014 · The Astrophysical Journal

Publication Stats

5k Citations
713.70 Total Impact Points

Institutions

  • 2008-2015
    • University of New South Wales
      • • School of Physics
      • • Department of Astrophysics and Optics
      Kensington, New South Wales, Australia
    • Carnegie Institution for Science
      • Department of Terrestrial Magnetism
      Washington, WV, United States
  • 2014
    • University of Texas at Austin
      • Department of Astronomy
      Austin, Texas, United States
    • American Museum of Natural History
      • Division of Physical Sciences
      New York City, New York, United States
    • University of Santiago, Chile
      • Departamento de Economía
      CiudadSantiago, Santiago, Chile
    • University of Hertfordshire
      • Centre for Astrophysics Research (CAR)
      Hatfield, England, United Kingdom
  • 2012
    • Australian National University
      • Research School of Astronomy & Astrophysics
      Canberra, Australian Capital Territory, Australia
    • Princeton University
      • Department of Astrophysical Sciences
      Princeton, New Jersey, United States
  • 2011
    • California Institute of Technology
      • Infrared Processing and Analysis Center
      Pasadena, CA, United States
  • 2001-2011
    • University of Sydney
      • School of Physics
      Sydney, New South Wales, Australia
  • 2003-2008
    • University of California, Los Angeles
      • Department of Physics and Astronomy
      Los Angeles, CA, United States
  • 2007
    • University of Porto
      • Centro de Astrofísica da Universidade do Porto
      Oporto, Porto, Portugal
  • 2004-2007
    • Australian Astronomical Observatory
      Sydney, New South Wales, Australia
  • 1995
    • Honolulu University
      Honolulu, Hawaii, United States