mapping the Universe
 in search of nearby worlds 


I specialize in making and analyzing high-resolution maps from large astronomical survey data sets. Much of my work has focused on processing infrared images from NASA's NEOWISE mission, repurposing this vast asteroid-hunting data set for astrophysics beyond the inner solar system. I am using NEOWISE data to search for cold nearby worlds, including brown dwarfs in the solar neighborhood, wide substellar companions, and the hypothesized Planet Nine. I also play a key role in several wide-area optical imaging surveys, particularly DECaLS and MzLS.

I'm currently a staff astronomer at NSF's NOIRLab in Tucson, Arizona, where I previously spent a year as a NASA Hubble Fellow. At NOIRLab, I am a member of Rubin Observatory's Community Science Team (CST). I earned a Ph.D. in physics from Harvard University in 2015. Before that I was an undergraduate at Stanford University, where I received a B.S. in physics in 2010.

Backyard Worlds: Planet 9

I co-founded this citizen science motion search, built around my WISE coadds.

Backyard Worlds: Cool Neighbors

I'm the PI of this NASA-funded citizen science project!

JWST Cycle 2 Program

I'm the PI of an approved Cycle 2 JWST program to obtain the first spectrum of the coldest known halo brown dwarf (WISEA 1534-1043 a.k.a. "The Accident").

DESI Commissioning

I was a core member of the Dark Energy Spectroscopic Instrument (DESI) commissioning team. My first-author SPIE paper shows a small sampling of my DESI commissioning work.

DESI Imaging Surveys

I'm a core member of the DESI imaging surveys team, producing optical catalogs 1.5-2 mags deeper than SDSS across 20,000 square degrees of sky.

WISE Coadds

I've reprocessed more than 300 terabytes of WISE images to create the deepest ever full-sky maps at 3-5 microns.

Spitzer Cycle 14 Campaign

I'm the PI of an approved Spitzer program that has imaged hundreds of extremely cold and fast-moving brown dwarf candidates newly revealed by combining the full WISE and NEOWISE data sets.

WISE Planet Nine Search

I have performed the deepest and widest area WISE-based search for Planet Nine.

The unWISE Catalog

We have published the deepest ever 3-5 micron full-sky catalog, featuring over 2 billion unique WISE-selected sources.

unTimely Catalog

A full-sky, time-domain version of the unWISE Catalog.

WISE Dust Map

I created a full-sky, high-resolution map of mid-infrared dust emission.


Accurate motion measurements for more than a billion infrared sources based on my time-resolved WISE coadds.

Data Releases

Full-sky WISE/NEOWISE-Reactivation Coadds:,, IRSA

Full-sky, Time-domain, Mid-infrared unTimely Catalog,, GitHub

Full-sky, WISE-selected "unWISE Catalog":, Astro Data Lab, IRSA, Vizier

DESI imaging surveys DR1-DR9:, Astro Data Lab

Full-sky CatWISE proper motion catalog:, Astro Data Lab, Vizier

Planck Full-sky Dust Model:

WISE Full-sky 12 micron Dust Emission Map:

DECam Galactic Plane Survey (DECaPS):, Astro Data Lab

NOIRLab Source Catalog:


See Complete List @ NASA ADS

Viewers / Visualizations

Time-resolved WISE/NEOWISE Coadds -- WiseView (primary author: Dan Caselden) [ASCL]

Full-depth WISE/NEOWISE Coadds -- Imagine Sky Viewer (primary author: Dustin Lang)

unTimely Catalog -- unTimely Catalog Explorer (primary author: Frank Kiwy) [ASCL]


Dark Energy Spectroscopic Instrument (DESI, builder)

Vera C. Rubin Observatory (Community Science Team)

Backyard Worlds: Planet 9 (co-founder)

Backyard Worlds: Cool Neighbors (founder, PI)

CatWISE (founding Co-I)

Dark Energy Camera Legacy Survey (DECaLS, core team member)

MOSAIC-3 z-band Legacy Survey (MzLS, core team member)

Dark Energy Camera Galactic Plane Survey (DECaPS)

LSST Stars, Milky Way & Local Volume Science Collaboration (SMWLV)

LSST Solar System Science Collaboration (SSSC)

LSST Dark Energy Science Collaboration (DESC)

LSST Active Galactic Nuclei Science Collaboration (AGN SC)

LSST Transients and Variable Stars Science Collaboration (TVS)

LSST Informatics & Statistics Science Collaboration (ISSC)

NOIRLab Source Catalog (NSC)


I co-founded Backyard Worlds: Planet 9, a Zooniverse project consisting of an all-sky crowdsourced motion search built around my time-resolved WISE/NEOWISE coadds. Since launching in February 2017, over 150,000 citizen scientists have contributed to our total of more than 10 million Backyard Worlds classifications. These contributors include residents of all 50 US states and 167 countries. Backyard Worlds now counts 79,000 registered users, and has benefited enormously from the enthusiasm and dedication of our diverse group of volunteers, some of whom have gone on to receive media recognition for their participation. Four citizen scientists are co-authors on the project's first peer-reviewed publication.

Credit: NASA's Goddard Space Flight Center Conceptual Image Lab/Krystofer D.J. Kim


My work, particularly in relation to citizen science, "big data", high performance computing, and Planet Nine, has been widely featured in local, national and international media. A partial list of articles quoting or mentioning me by name is provided below. I have also discussed my research during a number of radio and television appearances.

The Wall Street Journal : Supercomputer Embarks on Effort to Help Map the Universe, Dark Energy and All
Newsweek : What's your moonshot? Aaron Meisner and Backyard Worlds Want to Discover Our Solar System's Ninth Planet
CNN : Citizen scientists help discover 95 brown dwarfs that are neighbors of our sun
CBC Radio One : Amateur astronomers use the 'mark one eyeball' to find brown dwarf stars
NASA Feature : Citizen Scientists Help Create 3D Map of Cosmic Neighborhood
BBC : Backyard Worlds: One hundred new 'cool worlds' discovered
KGUN9 Tucson : Astronomers are trying to measure the effects of dark energy on the expansion of the universe
Berkeley News : UC Berkeley, NASA looking for citizen scientists to help find Planet 9
Scientific American : Looking for Planet Nine, Astronomers Gaze into the Abyss
NASA Feature : NASA-funded Website Lets Public Search for New Nearby Worlds
Berkeley Lab : Attention Earthlings: Help Wanted in Finding a New Planet
USA Today : NASA wants you - to find a missing planet
Daily Cal : Two UC Berkeley Researchers Recognized in Forbes '30 Under 30 in Science' List
HubbleSite : NASA Awards Prestigious Postdoctoral Fellowships
Die Welt : Jeder soll bei der Jagd auf Planet Neun mithelfen


950 North Cherry Ave.
Tucson, AZ 85719