This Spring at DiRAC we are watching something amazing blossom – and I don’t just mean the iconic Cherry Blossoms at the University of Washington, which were in peak bloom at the end of March this year! At the end of February, after nearly 20 years of development, the Rubin Observatory began its first phase of science. Real-time “Alerts” are now flowing from the Simonyi Survey Telescope in Chile, and being broadcast to astronomers around the world. It was a powerful and joyous moment, watching Prof. Eric Bellm and Dr. Ian Sullivan, showcase the very first alerts to the entire Rubin/LSST team.
Our goal now is to discover the surprises that will bloom from this new data. Last week DiRAC wrapped up Winter Quarter with a “First Alert Sprint”, where astronomers of all experience levels from the UW Astronomy Department came together to explore the millions of Alerts already released. In one day we discovered new pulsating stars in the far reaches of our Galaxy, looked at some “nearby” supernovae (only 900 million light years away!), and recovered comets whose tails had pushed them away from their “expected” positions,
On a personal level, I’m extremely proud of soon-to-be PhD, Andy Tzanidakis, whose recent discovery and analysis of “Gaia-GIC-1” has been getting some well deserved attention. Found using Gaia data, this is one of the very few planetary giant impact candidates ever observed… and based on its position in the sky it should be a perfect test case for Rubin! In the 10-year LSST survey, we might discover hundreds of such systems, helping determine how common Moon-forming impacts are. Well done Andy!
And that’s just one of the many new excellent studies we’ve highlighted in this Quarter’s Newsletter and on our website. As always, be sure to check back regularly for updates from our team… I can’t wait to see what other surprises are waiting to bloom this coming Spring!
I’m Joe, a new DiRAC Postdoctoral Fellow working within the solar system group here at UW. I came over from Queen’s University Belfast in Northern Ireland, where my PhD focused on preparing for the LSST at the Vera C. Rubin Observatory – specifically modeling how many outer solar system objects like Centaurs and Neptune Trojans the survey will detect, and how well we’ll be able to characterize them.
Joseph Murtagh
Now that Rubin is actually producing data, I’m in the exciting position of being able to test my predictions for the first time. My focus at DiRAC is going to be on using early Rubin observations alongside years of archival survey data to build composite light curves to get a more complete picture of how active outer solar system objects behave, which is something that just hasn’t been possible at this scale before. In parallel, I’m looking forward to comparing real detections against my population-level predictions I built during my PhD, and using both to think about which objects are most in need of targeted follow-up and where best to do that.
Alongside that simulation work, I have also studied real objects like Chiron and 103P using survey data from ATLAS and ZTF, and follow-up observations from facilities like LCO and the Liverpool Telescope in order to probe their activity evolution of many years. From this, I’ve managed to capture the longest continuously monitored and densely sampled active period yet recorded for Chiron over the last 50 years, providing a unique opportunity to study the decay of Centaur activity in real time.
Our 2025 Annual Report is now available, highlighting a remarkable year for DiRAC.
From new discoveries and major survey milestones to growing collaborations and student achievements, the report captures a year in review and celebrates the breadth of our community’s work. We encourage everyone to take a moment to reflect on the team’s accomplishments and the momentum we’ve built together.
Thank you to everyone whose contributions made 2025 such a successful year.
The first Rubin real-time alert has arrived, the event was led by Prof. Bellm joined by his team at the University of Washington.
This milestone marks the beginning of a new era in time-domain astronomy, with rapid alerts enabling discoveries across the dynamic sky. Learn more about this exciting achievement and what it means for Rubin science in the full press release here.
In the October 2025 newsletter, we reported the discovery of 19 ultra- to super-fast rotating asteroids identified among the first roughly 2,000 asteroids discovered with the NSF-DOE Vera C. Rubin Observatory, including the fastest spinning large asteroid found to date, 2025 MN45.
The findings were published in a paper in The Astrophysical Journal Letters on 7 January 2026, led by UW Astronomy Affiliate Assistant Professor Sarah Greenstreet, UW Astronomy graduate student Chester Li, UW Astronomy postdoctoral scholar Dmitrii Vavilov, UW Astronomy undergraduate student Devanshi Singh, and their colleagues. Coincident with the paper publication was a Rubin Observatory press release and a press conference held at the 247th meeting of the American Astronomical Society (AAS) in Phoenix, Arizona.
The coming year marks an exciting turning point at the DiRAC Institute. Vast new datasets from the Rubin Observatory are about to become available, and our students and researchers are preparing to make breakthroughs that could reshape our understanding of the Universe.
To seize this moment, we need your support. Your generosity ensures our team has the resources to turn incoming data into real-time discoveries.
Together, we can empower the next generation of scientists and unlock insights that will inspire the world.
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.
