Letter from the Director

Prof. James R. A. Davenport

Dear friends,

Fall quarter is my favorite time of the year at the University. We get to welcome our new graduate students, undergrads come back to the campus, and the work of teaching, research, and engaging the community begins in earnest. This is the time when new ideas begin to take shape, projects start, and everything seems possible.

I’m feeling a sense of almost unbounded possibility especially this year at DiRAC, as we are working through the first days of the Rubin Observatory’s operations. This summer we celebrated major milestones, including the amazing “First Look” event we hosted at Kane Hall in June. As the “commissioning” phase comes to a close, and the Observatory prepares for full operations near the end of the year, our team is preparing for a flood of science and discovery.

Trophies for the first research submitted from the DiRAC Data Preview sprint in mid 2025.

We were able to practice a bit of this Rubin-driven discovery over the summer, thanks to the first “Data Preview” that the Observatory published. With truly a tiny sliver of LSST/Rubin data in hand, students and faculty from our entire department came together for a week to explore and collaborate. These kinds of “sprints” are a fun way for everyone to quickly learn new skills, and for our team to push out early science. I promised fabulous prizes for the first publications to come out of this Data Preview sprint, and I’m especially proud of the graduate students David Wang and Tobin Wainer who took home the trophies!

In the Newsletter you’ll see profiles from many of our research programs. Our Solar System group is now firmly established worldwide as one of the premier groups working on asteroids, comets, and the enigmatic “interstellar objects”, and I’m in awe at how quickly they rallied the Rubin community to study the incredible new object, 3I/ATLAS. I am baffled and fascinated by the discovery of ultra-fast rotating asteroids, which Sarah Greenstreet’s team has recently announced. Our newest postdoctoral fellow, Nick Tusay, is broadening our Time Domain group’s expertise into data from JWST and the new field of disintegrating exoplanets. The science at DiRAC continues to evolve and explore some of the most exciting topics across astrophysics!

I’m also thrilled that we are beginning the search for our next cohort of DiRAC postdoctoral researchers, who will be pushing the frontiers here at UW of science as Rubin makes its first full data release. Thanks to the support of our community, and especially the incredible partnerships with the Simonyi and Frink families, and the B612 Institute, we are able to continue supporting innovative science, as well as continue building a welcoming and energetic environment for discovery. I am so grateful for the many opportunities I’ve had at DiRAC, and being able to continue this Fellowship program for the next generation of astronomers is a dream come true.

Here’s to a Fall full of new beginnings, community, and exciting discoveries.

Keep looking up!

Jim Davenport
DiRAC Director

Image by Raymond Smith Photography

Meet DiRAC’s Research Team: Nick Tusay

We are pleased to welcome Nick Tusay, who joined the team this September as a DiRAC Postdoctoral Fellow. Nick focuses on the search for extraterrestrial intelligence (SETI) and habitable worlds research. His SETI work has been executing and analyzing the results of novel search strategies to look for radio technosignatures using observatories like the Green Bank Telescope and the Allen Telescope Array. His work on exoplanets has largely been focused on directly measuring the chemical components of disintegrating rocky bodies around main sequence stars to test our understanding of planet composition using both state-of-the-art ground-based optical observatories as well as space-based observatories like JWST. 

Nick is excited to be co-PI on a JWST Cycle 4 Program to observe a recently discovered disintegrating exoplanet, BD+05 4868 Ab, executing this October. Using transmission spectroscopy in mid-infrared, his team will measure the spectrum of the dusty effluents coming off the planet and try to match that with features of known materials. It’s an exciting and rare opportunity to examine the interior composition of a rocky exoplanet around a main sequence star. 

Ultra-fast rotators among Rubin’s first asteroid discoveries

The NSF-DOE Vera C. Rubin Observatory’s First Look media event that took place on June 23, 2025 in which the first LSST Camera commissioning images were released, included the announcement of its first asteroid discoveries – 2,103 discoveries in all. The roughly 340,000 individual detections in which the 2,103 discoveries were made span 9 nights between April 21 and May 5, 2025. With a faint magnitude range (~23-25 mag) and dense temporal sampling under an irregular, commissioning‑driven cadence, the Rubin First Look observations provide an ideal testbed for determining asteroid rotation periods, including the detection of rapid rotation. In a paper, currently in press in The Astrophysical Journal Letters, NSF NOIRLab Assistant Astronomer and UW Astronomy Affiliate Assistant Professor Sarah Greenstreet, UW Astronomy graduate student Chester Li, UW Astronomy postdoctoral scholar Dmitrii Vavilov and their colleagues present light curves, rotation periods, and colors for the first asteroid discoveries made with the NSF-DOE Vera C. Rubin Observatory. 

Magnitude (brightness) over time for Rubin First Look Solar System object discovery, 2025 MM81, both for the full observation period (top; MJD=modified Julian date, covering 25 April 2025 to 5 May 2025) and zoomed-in on a single night (bottom; 60797 MJD = 2 May 2025) to see the brightness variation. Observations were taken using three filters (g-, r-, and i-band) covering different wavelength ranges; the number of observations in each band is shown in the legend. The magnitude (brightness) variation, its extent (approx. 1.2 magnitudes), the object’s rotation period (approx. 0.045 days = 1.1 hr), and even its colors (e.g., g – r ~ 0.6) can be determined directly from the raw photometry from a single night of observations.

The paper includes modeled light curves and derived rotation periods and colors for the 2,103 objects, finding 75 asteroids with reliable, robust rotation periods spanning < 2 minutes to > 21 hours; each of the 75 asteroids in the data set reside in the Solar System’s main asteroid belt between the orbits of Mars and Jupiter. Notably, they find 18 super-fast rotators with periods shorter than the 2.2-hr spin barrier; the spin barrier is the maximum rotation rate an object can sustain before the centrifugal force overcomes self-gravity, potentially leading to structural fragmentation of the asteroid or the formation of a binary asteroid. Surprisingly, they additionally find that Rubin-discovered main-belt asteroid (MBA) 2025 MN45 is now the fastest rotating known asteroid with a diameter larger than 0.5 km (longer than the length of 5 football fields), rotating once every 1.9 min! Along with Rubin-discovered near-Earth object (NEO) 2025 MJ71 (3.7 min) and MBAs 2025 MK41 (3.8 min), 2025 MV71 (13 min), and 2025 MG56 (16 min), these five ultra-fast rotators now join a couple of previously-known near-Earth asteroids as the fastest spinning sub-km asteroids known.

As this study demonstrates, even in early commissioning, Rubin is successfully probing the previously sparsely sampled population of large-sized asteroids that reside at greater distances than other astronomical surveys have been able to observe spinning at these very fast rotation speeds. Although this data set consists of observations taken at a different cadence, subject to the requirements of Rubin’s commissioning period, than will be followed during Rubin’s Legacy Survey of Space and Time (LSST), expected to start later this year, with millions of asteroid discoveries expected from the survey in the coming years, the findings of this study are just the beginning of the exciting science the Rubin Observatory will unlock and the astronomers at UW Astronomy’s DiRAC Institute are poised to lead.

About Sarah Greenstreet

Sarah Greenstreet is a tenure-track assistant astronomer at the NSF National Optical-Infrared Astronomy Research Laboratory (NOIRLab) and an affiliate assistant professor in the University of Washington’s Department of Astronomy. She is also a member of the Rubin Observatory Community Science Team and has served as the Lead for the Rubin Observatory Solar System Science Collaboration’s Near-Earth Objects and Interstellar Objects Working Group for the past seven years. Prof. Greenstreet’s research program broadly focuses on orbital dynamics, characterization, and impacts of small bodies across the Solar System, with a particular focus on the rarest and most unusual asteroids. To learn more about her research, please visit her website: www.sarahgreenstreet.com.

About Dmitrii Vavilov

Dmitrii Vavilov is a postdoctoral researcher at the University of Washington and a former Marie Skłodowska-Curie Fellow at the Paris Observatory. He studied astronomy at St. Petersburg State University and earned his Ph.D. in celestial mechanics from the Institute of Applied Astronomy of the Russian Academy of Sciences. His research focuses on the dynamics and physical properties of small Solar System bodies (like asteroids and comets) from their dynamical evolution to shape transformations. He developed the Partial Banana Mapping (PBM) method, an efficient approach for modeling orbital uncertainties to predict Earth-impact probabilities, precoveries, and follow-up observations. He is a member of the International Astronomical Union, and asteroid (34583) DmitriiVavilov has been named in his honor.

About Chester Li

Zhuofu (Chester) Li is a Ph.D. student studying Astrophysics, Statistics, and Data Science at the University of Washington. His research integrates data science, astrophysics, and machine learning to explore the mysteries of the Universe. Chester’s recent work includes estimating rotation periods for Jupiter Trojans using Zwicky Transient Facility lightcurves, identifying temporary Jovian co-orbitals through large-scale N-body simulations, and applying simulation-based inference with normalizing flows to constrain dark matter using stellar streams. He is also the founder of the UW Data Science Society, where he builds interdisciplinary collaborations between astronomy, statistics, and computer science.

Exploring the Dynamic Solar System with Rubin Observatory and Citizen Science

3I/ATLAS, as observed by the NSF-DOE Vera C. Rubin Observatory on July 3, 2025, shows evidence of cometary activity in the form of a short, faint tail and dust cloud pointed in the upper-left direction. Image credit: Chandler et al. 2025.

DiRAC postdoctoral scholar Colin Orion Chandler is leading innovative efforts to explore small bodies in our Solar System using the upcoming Vera C. Rubin Observatory. As Project Scientist for the LSST Interdisciplinary Network for Collaboration and Computing (LINCC) Frameworks, Chandler’s work bridges cutting-edge data systems with frontier planetary science. His Rubin Comet Catchers project—the first Rubin-based Citizen Science program—invites volunteers worldwide to help identify comets and active asteroids hidden in Rubin’s vast imaging data. Since its launch in July 2025, over 1,500 participants have contributed more than 1.5 million classifications, demonstrating the power of community-driven discovery at LSST scale.

Chandler also co-leads the Rubin observations of interstellar comet 3I/ATLAS, representing the first scientific paper derived from Rubin data. The discovery revealed that Rubin had serendipitously imaged the interstellar visitor prior to its detection, offering invaluable insights into the observatory’s capabilities for identifying and characterizing future interstellar objects. With Rubin expected to find 5–50 such visitors over its 10-year survey, this work underscores the observatory’s transformative role in Solar System science and interstellar research.

Together, these efforts highlight how DiRAC researchers are pioneering the intersection of AI-assisted Citizen Science and next-generation astronomical surveys. From training “TailNet” neural networks on volunteer data to coordinating rapid follow-up of unexpected phenomena, Chandler’s team is forging the framework for large-scale, inclusive discovery—ensuring that Rubin’s once-in-a-generation data revolution engages both scientists and the public in revealing our dynamic Solar System.

Colin Orion Chandler
Project Scientist for the LSST Interdisciplinary Network for Collaboration and Computing (LINCC) Frameworks project

About Colin Orion Chandler

Colin Orion Chandler (DiRAC and University of Washington) is a Project Scientist for the LSST Interdisciplinary Network for Collaboration and Computing (LINCC) Frameworks project, and serves as co-chair of the LSST Solar System Science Collaboration. Colin earned his Ph.D. in Astronomy and Planetary Science from Northern Arizona University, where he was an NSF Graduate Research Fellow, after he graduated from San Francisco State University with a BS in Physics with a Concentration in Astrophysics. He specializes in solar system science (especially cometary activity), Citizen Science, and working with large-scale archival image data. Colin founded the NASA Partner program “Active Asteroids” (http://activeasteroids.net), a Citizen Science program hosted on Zooniverse. Colin is also an experienced observer, utilizing both ground- and space-based telescopes as part of his work. 

Report on LEO satellite impacts on ground-based optical astronomy for the Rubin Observatory LSST

In August 2025, Meredith Rawls, UW/DiRAC Research Scientist and Co-Lead of SatHub at the IAU Centre for the Protection of the Dark and Quiet Sky (CPS), and Brianna Smart, UW/DiRAC Research Scientist, attended an NSF-funded workshop on satellite constellations and Rubin Observatory at UC Davis.

The workshop resulted in a report titled, “Report on LEO satellite impacts on ground-based optical astronomy for the Rubin Observatory LSST,” which was shared on arXiv in September (v1). The report aims to minimize the impact of Starlink-like constellations on LSST science and acknowledges it cannot encompass all satellites or all observatories. Nevertheless, in addition to affirming previous recommendations, including satellite darkening mitigations, low orbital altitudes, and timely data sharing of satellite positions and trajectories, the report introduces new ones, such as coordinated de-orbit strategies, developing metrics that account for the impact of full constellations, and building a comprehensive database of satellite signatures in LSST data down to low surface brightness.

Read the report here.

About Meredith Rawls

Meredith Rawls is a research scientist in the Department of Astronomy and DiRAC at the University of Washington. She writes software to handle terabytes of nightly data from Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST), which will ultimately become the highest resolution movie of the night sky ever made. She earned a BS from Harvey Mudd, a MS from San Diego State, and a PhD from New Mexico State. Her background is in stellar astrophysics, but lately she studies the plethora of newly-launched low-Earth-orbit satellites in the hopes observers worldwide don’t lose the night sky. She lives with her family in Seattle, enjoys playing viola, and primarily gets around by e-bike.

About Brianna Smart

Brianna Smart is a research scientist in the Department of Astronomy and DiRAC at the University of Washington. She writes software as part of the Alert Productions Data Management group in support of the Vera C. Rubin Observatoriy’s Legacy Survey of Space and Time. She earned her B.S. in Astronomy and Physics at the University of Arizona, and her M.S. and PhD from The University of Wisconsin. Brianna has a varied background in astronomy from exoplanets to stellar dynamics to diffuse ionized gas. She also enjoys any science topic related to the Magellanic Clouds.

Letter from the Director

James R. A. Davenport,
DiRAC Director

Dear friends of DiRAC,

This summer marks an exciting turning point, not just for our Institute, but for astronomy as a whole: after years of anticipation, the construction of the Vera C. Rubin Observatory is finally complete, and the first incredible images have been shared with the world!

It’s amazing to think that this project started almost 20 years ago, and I’m so proud that Seattle and the University of Washington have remained leaders in its design, development, and now discovery with LSST. I hope you will join us in Kane Hall on June 26 as we share these images with our community, and tell a few of the stories of the brilliant and hard-working people who have made this dream a reality.

The summer also marks a turning point for the leadership of DiRAC. I am deeply honored to step in to the role as Director of the DiRAC Institute this year. I joined DiRAC 8 years ago a Postdoctoral Fellow, drawn by the promise of new datasets and a collaborative environment where wild or even silly ideas could find a home. Now as a professor and Director, my goal is to take the scientific momentum built by Andy Connolly and Mario Juric, and support this amazing group of students, developers, and researchers into an era of unprecedented discovery. These are uncertain times for science. The broader funding and academic landscape is rocky, and it can feel harder than ever to plan for the long term. But if these past 8 years have taught me anything, it’s that imagination, persistence, and compassion are powerful force multipliers. Whether we’re tracking near-Earth asteroids, developing novel algorithms, or chasing the weird and wonderful outliers in our data, we thrive when we let curiosity lead the way.

I am so grateful that our community has continued to support us, funding a 4th year of our Summer Research Prize program, and new generations of Postdoctoral Fellows at DiRAC. So here’s to the coming decade of discoveries with Rubin/LSST. Here’s to students asking bold questions from our data. And here’s to finding joy – even a little absurdity – in the vast puzzle of the cosmos.

Thank you for being part of this journey with us, and keep looking up.

Jim Davenport
DiRAC Director

Welcome to your First Look at the cosmos from the Rubin Observatory

Rubin Observatory has released its first look at the night sky—and the images are nothing short of spectacular. Visit the Rubin Observatory to see and learn more.

On Monday morning, June 23, 2025, we gathered in a full UW Planetarium to witness the release of Rubin Observatory’s first images—an extraordinary milestone that marks years of effort and dedication from teams across UW and DiRAC. It was a powerful moment of recognition for the many individuals who have contributed to making this achievement possible.

As our colleague and Rubin Director, Prof. Željko Ivezić, announced the discovery of the first asteroids identified in this new dataset, we applauded the outstanding work of our Solar System team. The variable stars revealed today offer an early look at the groundbreaking, real-time discoveries that will soon be enabled by the Alert and Data Management systems led here at UW, along with the Time Domain Analysis group. The search for dark matter remains one of Rubin’s most ambitious scientific goals, and even today, we are already engaged in spirited discussions about how to interpret the rich detail in these first images.

This milestone marks the beginning of a new era in astronomy, as Rubin prepares to launch the Legacy Survey of Space and Time (LSST), the most ambitious sky survey ever undertaken. To celebrate this exciting moment, we invite you to join the local UW Rubin team on Thursday, June 26th at 7:00 PM for a special event featuring a free public lecture.

Come be part of the celebration and learn more about the science and people behind this groundbreaking project.

REGISTER TODAY HERE

June 26, 2025

7:00 PM-8:30 PM

UW Kane Hall (KNE) 130

Lecture | Rubin Observatory’s First Look and exciting new era of discoveries at the University of Washington!

Join us for this free public event at the University of Washington and be part of the beginning of an exciting new era of discovery!

REGISTER TODAY HERE

June 26, 2025

7:00 PM-8:30 PM

UW Kane Hall (KNE) 130

This milestone represents over two decades of dedication and collaboration from the global Rubin community. We are especially proud to honor the University of Washington Rubin Team, whose leadership and involvement as one of four founding institutions, have been instrumental in bringing this vision to life.

The DiRAC Institute is thrilled to host this event, celebrating UW’s pivotal role and inviting the Seattle community to share in the excitement of discoveries to come.

Photograph by Marcos Zegers

This is more than an astronomy event — it’s a celebration of human curiosity, collaboration, and imagination. Whether you’re a student, researcher, space enthusiast, or simply someone who looks up at the night sky in wonder, you’re invited to be a part of this historic moment.

Speakers

Prof. Zeljko Ivezic: Professor Željko Ivezić of the University of Washington has been associated with Rubin Observatory since its inception in the early 2000’s (then called LSST Project). As LSST Project Scientist from 2004 to 2021, Željko has chaired the LSST Project Science Team and played a major role in both internal and external reviews of the project. In 2022, he became Director of the Rubin Observatory Construction Project. Scientifically, Željko’s expertise is in survey astronomy in a variety of fields ranging from solar system science to studies of the structure of the Milky Way and cosmology.

Prof. Mario Juric: Prof. Mario Juric is the co-director of UW’s Institute for Data-intensive Research in Astrophysics and Cosmology (DiRAC) and Principal Investigator (PI) of UW’s contribution to Rubin Observatory construction and operations. He has been involved with Rubin since 2008, including defining Rubin’s data products and leading the multi-institutional Rubin Data Management team through R&D and early construction. Prof. Juric’s team at UW is responsible for scanning the ever-changing sky with Rubin: from detecting the most energetic explosions in the Universe, to discovering asteroids that could potentially be on a collision course with the Earth.

Prof. Andy Connolly: Professor Andy Connolly is the Director of UW’s eScience Institute, and a professor in the Department of Astronomy. Professor Connolly studies cosmology and the formation of structure within our universe using large astronomical surveys ranging from the Sloan Digital Sky Survey to the Legacy Survey of Space and Time (LSST). He has been involved in the design, construction, and commissioning of Rubin since 2006 and currently works on the Active Optics System that ensures that the images from the Rubin Observatory will be sharp and clear. He leads LINCC Frameworks, a program supported by Schmidt Sciences to develop the software and tools that will make science discoveries possible at the scale of the Rubin data. Beyond his scientific research, Professor Connolly is interested in using technology to increase access to scientific data and to improve the educational experiences of students.

The Simonyi Survey Telescope now has its mirrors and a camera in place. (Credit: Rubin Observatory)

About Vera C. Rubin Observatory

High in the Chilean Andes, the NSF–DOE Vera C. Rubin Observatory is a next-generation facility named after astronomer Vera Rubin, whose work provided key evidence for dark matter. Jointly funded by the National Science Foundation and the U.S. Department of Energy, Rubin is set to transform our understanding of the Universe.

Its 8.4-meter Simonyi Survey Telescope, featuring the world’s largest digital camera, will scan the southern sky every few nights for ten years—creating the most detailed time-lapse of the night sky ever captured.

Rubin data will deepen our understanding of dark energy and dark matter, trace the history of our solar system, detect asteroids and new worlds, and uncover cosmic phenomena we’ve yet to imagine.

UW DiRAC Institute

The DiRAC Institute is an interdisciplinary research center at UW focused on data-intensive astronomy. Established in 2017 with founding support from the Charles and Lisa Simonyi Fund for Arts and Sciences, and additional support from Janet and Lloyd Frink, NSF, WRF, U.S. Department of Energy, B612 Foundation, Heising-Simons, and Breakthrough Listen – the DiRAC Institute will help us make sense of the discoveries emerging from Rubin and the next generation of telescopes.

REGISTER FOR THE EVENT

Millions of new solar system objects to be found and ‘filmed in technicolor’ – studies predict

In preparation for the Rubin Observatory’s upcoming ten-year Legacy Survey of Space and Time (LSST), we helped develop Sorcha, a survey simulator tuned for LSST. Sorcha models the detection and discovery of a model solar system population by a model Rubin Observatory, allowing us to conduct synthetic ‘test’ surveys with different conditions and environments.

Researchers from the UW and Queen’s University Belfast believe that knowledge of the objects in the solar system will expand exponentially when a new telescope comes online later this year. Shown here is a visualization of what astronomers predict the NSF–DOE Vera C. Rubin Observatory’s LSST Camera will see, including asteroids and other objects in the sky.Sorcha.space/University of Washington

The first major result with Sorcha are the predictions of a high-fidelity simulation of our best current expectations for LSST against our best current understanding of the solar system. We find that Rubin will observe 5.4 million asteroids including millions with sufficient data for precise color fits and hundreds of thousands with shapes revealed through their rotational light curves.

Even more exciting than these predictions is Sorcha’s potential as a tool for debiasing — applying the measured survey efficiency to a model population, allowing for fair comparisons between Rubin’s real observationally-biased discovery catalogs and theorists’ models of the intrinsic distributions of solar system object parameters.

Read here a full article by Jackson Holtz

Letter from the Director

Prof. Mario Jurić

Dear DiRAC supporters,

Welcome to 2025 and to a new installment of our newsletter.

And what a year it’s been so far! In October of last year, after almost two decades of research, development, and construction, we welcomed the first engineering light with the test camera at the Rubin Observatory. The first image, unveiled at the January American Astronomical Society’s meeting by Rubin Construction director and UW DiRAC Faculty Prof. Zeljko Ivezic, shows the potential of the observatory and foreshadows the next decade of discovery. We’re now working towards the first light with Rubin’s main camera, and marching towards the end of this year when Rubin will embark on its 10 year mission to map the Universe in both space and time.

Read more about Rubin, events at the Institute, profiles of our excellent DiRAC team members, as well as how our Prof. Nora Shipp won a Scialog Collaborative Innovation Award, in the main part of this newsletter.

But before I let you go, there’s one more thing… Following nearly five years of being at the helm of DiRAC, it’s a privilege to welcome Prof. Jim Davenport as the new incoming Director! Jim is Research Associate Professor in the department of Astronomy, and has been DiRAC’s Associate Director for nearly all of my tenure. His impact on the institute cannot be underestimated: from revitalizing our time-domain program to leading numerous outreach and education initiatives — including the highly successful DiRAC Undergraduate Summer Prize program.

As I prepare to take a Rubin-focused sabbatical next year, I’m incredibly grateful to Jim for agreeing to step up and take on this responsibility. As we finally enter the age of Rubin, there’s no one better I can imagine to lift the Institute to new heights!

Onwards and upwards,

Mario Jurić
DiRAC Director
Professor, Department of Astronomy