Erik J. Tollerud

I'm an Associate Astronomer* and the Data Science Mission Office Project Scientist at the Space Telescope Science Institute in Baltimore, MD. I am also a founding coordinator of the Astropy Project.

ADS Publications arXiv Publications

Contact Me: etollerud (at) stsci (dot) edu

* without tenure


My astrophysics research focuses on Local dwarf galaxies and what they have to say about cosmology.

Observations of Local dwarf galaxies

I observe dwarf galaxies of the Local Group and Local Volume to try to understand their properties and constrain galaxy formation models. My observations include resolved star spectroscopy, deep imaging both from the ground and the Hubble Space Telescope, and radio searches for neutral hydrogen (HI).

Local Group dSph and Near-Field Cosmology

I compare the faintest known galaxies to cosmological models like ΛCDM. Because these galaxies are so faint, they are dark matter-dominated, and provide some of the best windows into the nature of dark matter. They also provide important insights into early universe processes like reionization.

Image Credit: Aquarius Project

Using large surveys to understand local dwarfs

I help build and use large multiwavelength surveys like SAGA, DELVE, the Sloan Digital Sky Survey, and GALFA-HI to place Local Group galaxies in a cosmological context. I also use them to search for new dwarf galaxies.

Image Credit: SDSS

Code Development

I also work on a number of open-source software projects, particularly for science with Python. I highlight some of these below, but see my github repository page for a more complete list.


Astropy is a community astronomy library for astronomy. I am on the coordinating committee and have several other key roles.

Open Astronomy

OpenAstronomy is a collaboration between open source astronomy and astrophysics projects to share resources, ideas, and to improve code.


An open-source project with the functionality of SOFA but with modern distribution and fully FOSS-compatible licensing.

My Curriculum Vitae

Research Positions

  • Assistant Astronomer (tenure-track) and DATB Project Scientist, 2017-present

    Space Telescope Science Institute, Baltimore, MD, USA

      • Giacconi Fellow, 2015-2017

        Space Telescope Science Institute, Baltimore, MD, USA

        • Hubble Fellow, 2012-2015

          Yale University, New Haven, CT, USA

        • Graduate Student Researcher, 2007-2012

          University of California, Irvine, CA, USA

          James Bullock, Elizabeth Barton

        • Honors Research Thesis, 2005-2006

          University of Puget Sound, Tacoma, CA, USA

          James Bernhard

        • NASA Space Grant Intern, Summer 2005

          Jet Propulsion Laboratory, Pasadena, CA, USA

          Michael Hecht

        • microEP REU, Summer 2004

          University of Arkansas, Fayetteville, AK, USA

          John Shultz


  • University of California, Irvine Irvine, CA, USA

    Ph.D., Physics and Astronomy, June 2012

    Advisor: James Bullock

    Dissertation: "Local Group Dwarf Galaxies in the LCDM Cosmology: Theory Meets Observations"

  • University of California, Irvine Irvine, CA, USA

    M.S., Physics and Astronomy, June 2008

  • University of Puget Sound, Tacoma, WA, USA

    B.S., Physics, Math, May 2006

Observing Experience

  • Hubble Space Telescope
  • Anglo-Australian Telescope
  • Green Bank Telescope
  • Hubble Space Telescope
  • Keck Observatory (I and II)
  • Palomar Hale Telescope
  • UC Irvine Observatory
  • UCO/Lick Shane 3m Telescope
  • WIYN Telescope

Honors and Awards

  • PI Observing time awarded:
    • Hubble Space Telescope
    • Keck Telescope
    • Palomar Hale Telescope
    • WIYN Observatory
  • Co-PI, $900k for Sustaining and Growing the Astropy Project, a Data-Driven Discovery Initiative grant from The Gordon and Betty Moore Foundation , 10/2019
  • Giacconi Fellow, 9/2015-8/2017
  • Awarded $900k grant from STScI Strategic Discretionary Research Fund, 9/2016
  • Depsy research software ranking: 97th percentile, 10/2016
  • Hubble Fellow, 8/2012-8/2015
  • Fletcher Jones Fellow, 9/2011-6/2012
  • UC Irvine Graduate Dean's Dissertation Fellow, 6/2011 - 9/2011
  • UC Irvine School of Physical Sciences Faculty Endowed Fellow, 5/2011
  • Chambliss Astronomy Achievement Award, 217th AAS, 1/2011
  • Optical Society of America Art in Science Award [1], 11/2010
  • Publication Featured in Nature Research Highlights [2], 9/2008
  • GAANN Fellow, 6/2008-6/2011
  • Coolidge Otis Chapman Honors Scholar, 6/2006
  • Nominated member of Sigma Xi, 5/2006
  • Thomas Malcolm & Hilda Enden Jack Physics Scholar, 6/2005
[1]visualization later featured in news media incl. MSNBC, AFP, Science Daily,

Teaching and Outreach

  • Co-supervisor/mentor

    Graduate Students: Luis Vargas, Ana Bonaca, Lucas Viani (Yale), John Phillips (UC Irvine), Brett Morris (U of Washington).

    Undergraduate students: Kareem El-Badry, Emily Sandford (Yale), Karl Vyhmeister (U of Washington), Zé Vinicus (UFCG, Brazil).

  • JWST User Training Workshops, 1/2015, 11/2016

    Present and help organize day-long workshops on Python in Astronomy and associated James Webb Space Telescope data analysis tools.

  • STScI PyLunch Organizer, 2016-present

    Organize/present bi-weekly sessions to train STScI science staff in usage of Python programming language for astronomy.

  • Publication Featured in HubbleSite News Release, 8/2016

  • Speaker: Astro on Tap, New Haven

    Public talks at BAR Restauraunt and Nightclub in New Haven, CT.

  • COSMOS Teaching Assistant, 2007-2011

    Managed project groups and gave lectures to science-oriented summer camp for California high school students.

  • Public Lectures, UC Irvine Observatory, 2008-2012

  • UC Irvine Observatory Outreach Coordinator, 2006-2008

    Planned and executed nearly 100 outreach visits for K-12 schools, reaching roughly 3000 students.

  • Teaching Assistant, UC Irvine, Intro to Astronomy, 2008

  • Teaching Assistant, UC Irvine, Physics of Music, 2007

  • Teaching Assistant, UC Irvine, Intro to Astronomy, 2007

  • Teaching Assistant, UC Irvine, Astronomy Lab, 2007

  • Lab Assistant, Univ. of Puget Sound, University Physics, 2006

  • Lab Assistant, Univ. of Puget Sound, Waves & Optics, 2005

  • Lab Assistant, Univ. of Puget Sound, College Physics, 2005

Memberships, Service, and Committees

  • Member, American Astronomical Society (AAS)
  • Member, American Association for the Advancement of Science (AAAS)
  • Member, Sigma Xi
  • Journal Article Referee

    • Astrophysical Journal
    • Astrophysical Journal Letters
    • Astronomy & Astrophysics
    • Monthly Notices of the Royal Astronomical Society
  • Astropy Coordinating Committee Member, 2011-present

    Founding Member of planning board for project to develop Python programming language libraries for astronomy.

  • Lead Maintainer, astropy.coordinates, 2011-present

    Develop and manage community contributions to astropy sub-package on celestial coordinates and transformations between them.

  • Scientific Organizing Committee Chair, M31 Surveys Workshop

    Lead Organizer for Workshop on “Large Surveys of the Great Andromeda Galaxy: Resolved Galaxy Physics Beyond the Milky Way”, 7/2017 at Lorentz Center, Leiden, NL

  • Scientific Organizing Committee, Python in Astronomy 2017

    Organing workshop on Python in Astronomy, 5/2017 at Lorentz Center, Leiden, NL

  • Scientific Organizing Committee, Detecting the Unexpected

    Organizing Workshop on “Detecting the Unexpected: Dis- covery in the Era of Astronomically Big Data”, Planned for 2/2017

  • JWST Data Analysis Forum, 2015-present

    Contribute to sprints on development of software for James Webb Space Telescope data analysis tools.

  • STScI Galaxy Journal Club Organizer, 2015-present

    Organize weekly lunch talk/journal club section for STScI and JHU science staff with extragalactic interests.

  • Delegate, Maximizing Science in the Era of LSST Kavli Study, 5/2016

    Participate in workshop on study of US Optical/IR Capa- bilities needed in the LSST Era.

  • Scientific Organizing Committee, Python in Astronomy 2016

    Organized Workshop on Python in Astronomy at eScience Center in Seattle, WA, 3/2016

  • Panelist, Hubble Space Telescope Time Allocation Committee, 2014

    Reviewed and voted on proposed small/medium GO time proposals for use of HST.

  • NASA Earth and Space Science Fellowship Program Reviewer, 2014

    Reviewed and graded fellowship applications for graduate fellowship.

  • Yale Astronomy Colloquium Organizer, 2012-2014

    Invited colloquium speakers, organize schedule, introduce colloquium speakers.

  • Yale Galaxy Lunch Organizer, 2013-present

    Organize weekly lunch talk/journal club section for faculty, postdocs, and grad students with extragalactic interests.

  • Founder, Yale Organized Discussion of Astronomy, 2012-present

    Created weekly meeting or faculty, postdocs, and grad students to discuss recent results across Yale's subfields.

  • Yale Astronomy Colloquium Organizer, 2012-2014

    Organize colloquium speaker's schedule, introduce seminar speakers before their talks.

  • Associated Graduate Students of UCI Chief of Staff, 2011

    Representative on administrative committees, liaison to President.

  • UCI Graduate Council Representative, 2010-2012

    Representative to UC Irvine Academic Senate committee on graduate student curriculum development.

  • Organizer for UC Irvine "READ" journal club, 2009-2012

    Organized bi-weekly discussions of recent papers on ArXiv/astro-ph between graduate students, postdoctoral researchers, and faculty.

  • Co-Organizer, Astronomy Graduate Seminar, 2009-2010

    Organized weekly talks by graduate students and postdocs.

  • Founding Chair, UCI Physics Graduate Caucus, 2007-2010

    Created graduate student organization to provide peer advising and graduate student voice in departmental affairs.