My interests include large-scale data analysis projects, star formation, and the low-mass tail of the star-formation process.   As lead of the Pan-STARRS data analysis system, I spend much of my time working on running and improving the data analysis pipeline.  I’ve worked with collaborators (including M. Liu, N. Deacon, B. Goldman, C. Waters, W. Best, K. Aller) to use the Pan-STARRS dataset to find interesting low-mass brown dwarfs and free-floating planets in the nearby solar neighborhood.  We are working to characterize this population using photometry and astrometry from the PS1 survey.  I am also working (with C. Waters and C.-H. Lee) to use variable star populations to study the star formation history of the nearby galaxies M31 and M33.


Brown Dwarfs – I have been studying Brown Dwarfs in several contexts. As the co-Lead (with Wolfgang Brandner) of the PS1 Key Project 3 (Low-mass stars, brown dwarfs, and star formation), I have been working with the team of interested scientists to harvest brown dwarfs from the PS1 survey. I have been working, primarily with M. Liu, N. Deacon and IfA graduate students Z. Zhang, W. Best and K. Aller to find interesting brown dwarfs. One thrust of this work is to find the examples of brown dwarfs sampling extrema of the population phase space. In this context, our discovery of PSO J318.5-22, a free-floating planetary mass object, is exemplary. Local Solar Neighborhood – I have been funded by NSF to use the astrometric products of the Pan-STARRS survey to perform a census of the low-mass components of the local solar neighborhood. In this context, I am providing 50% funding and co-advising Will Best’s PhD work on the construction of volume limited sample of objects in the range L0 – T8. I am also funding IPP Postdoc Chris Waters at the 40% level to work on construction of a larger proper-motion selected sample of brown dwarfs. I am also using the precision astrometry from PS1 to measure parallaxes en masse of objects in the local solar neighborhood. Photometric and Astrometric calibration – As part of my development work for Pan-STARRS and Elixir, I have been investigating the limits of high-precision photometry and astrometry with CCDs. I have identified various interesting systematic structures in the Pan-STARRS imagery which we are able to correct, including a previously-unseen variation in the diffusion in CCDs associated with the doping variations. M31 Variables – I am continuing my work on M31 variables in collaboration with Chien Hsiu Lee (now NAOJ, formerly MPE). My science interest is to use the Cepheids and RR Lyrae as tracers of the star formation history. We have obtained short-period Subaru HSC data and are working to combine the PS1, CFHT and HSC datasets into an unparalleled M31 variability survey.


  • ADS Query for articles (excluding ATels, MPEC, etc) : https://tinyurl.com/2p8bchv5
  • ADS Query for Magnier et al papers : https://tinyurl.com/y784sryy


Fall 2023 :

ASTR 300 Observational Astronomy : Principles and techniques of optical and near-infrared astronomical observation. Astronomical coordinate systems. Telescopes, cameras, spectrographs, and detectors. Astrometry, photometry, and spectroscopy of astronomical objects

  • ASTR 300

Specialist, Pan-STARRS & Undergraduate Chair
Ph.D. 1993, MIT
B.W. 1989, MIT
  • Pan-STARRS
  • Low-Mass Content of the Solar Neighborhood
  • Andromeda Variability
IfA Mānoa, B-203A
(808) 956-6317(808) 956-6317