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.
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.
After the highly successful Rubin First Look press conference on June 23, 2025 in Washington D.C., where the first Rubin images were shared with the press and public, the Project focused on science verification and validation, and preparations for a series of Construction Completeness Reviews.
Science verification on-sky data taking was just completed on September 20, and resulted in a less extensive data set at the quality of LSST than originally planned. As a result, Data Preview and Data Release schedules are being re-optimized with external advice provided by Science Advisory Committee and Users Committee.
The transfer of authority from the construction project to the operations team will happen on October 24, during Construction Completeness Review 3 to be held in Chile. The Data Management Standards Reviews have been completed and confirmed by NSF and DOE. The public posting of the observing schedule is also confirmed, and Rubin is now in the 80-hour image embargo period. Criteria to start the LSST are given in ls.st/RTN-093 and Operations readiness review will provide a comprehensive basis for decision to start theLSST later this year.
The UW Alert Production Team celebrated the First Look milestone with several DiRAC-hosted events. Soon after, Rubin released Data Preview 1 containing commissioning data from the smaller ComCam camera. DiRAC hosted a successful DP1 sprint, which allowed members of the AP team to share knowledge with other scientists in the department and resulted in several research notes and papers. Since then, the team has continued to commission the image processing pipelines in preparation for public alert release and reporting discoveries of solar system objects to the Minor Planet Center.
Željko Ivezić Director of Rubin Construction Professor of Astronomy, University of Washington
Eric Bellm Research Associate Professor, University of Washington
About Željko Ivezić
Željko Ivezić (pronounced something like Gel-co Eva-zich) obtained undergraduate degrees in mechanical engineering and physics from the University of Zagreb, Croatia, in 1990 and 1991. He obtained Ph.D. in physics from the University of Kentucky in 1995, where he worked on dust radiative transfer models and wrote the code Dusty. He moved on to Princeton University in 1997 to work on the Sloan Digital Sky Survey, and took a professorship at the University of Washington, Seattle, in 2004. Željko’s scientific interests are in detection, analysis and interpretation of electromagnetic radiation from astronomical sources. His current focus is the Rubin Observatory and Legacy Survey of Space and Time, for which he serves as the Construction Project Director.
About Eric Bellm
Eric Belm is a Research Assistant Professor in the Department of Astronomy at the University of Washington and a Fellow of the DIRAC Institute. He is leading the development of major portions of two new large optical time-domain surveys. He is the Alert Production Science Lead for the Vera C. Rubin Observatory as well as Survey Scientist for the Zwicky Transient Facility. Eric is using optical variability data to search for hidden populations of neutron star and black hole binaries in our Galaxy. His research includes observation, instrumentation, and large-scale data analysis.
UW Lecture: A New Era of Cosmic Discovery with the Rubin Observatory
The DiRAC Institute hosted a special event at the University of Washington to celebrate Rubin’s First Look, featuring a public lecture at Kane Hall. Recording of the lecture is below.
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.
Sarah Greenstreet
Dmitrii Vavilov
Chester Li
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.
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.
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.
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.
