On Feb. 24, astronomers’ computers around the world lit up with a deluge of cosmic notifications — 800,000 alerts about new asteroids in our solar system, exploding stars across the galaxy and other noteworthy changes in the night sky. The discoveries were made by the Simonyi Survey Telescope at the in Chile and distributed globally within about two minutes.

That flurry of notifications marked the commencement of the observatory’s Alert Production Pipeline, a sophisticated software system developed at the 91̽�� that is eventually expected to produce up to seven million alerts per night.

“Rubin’s alert system was designed to allow anyone to identify interesting astronomical events with enough notice to rapidly obtain time-critical follow-up observations,” said , a research associate professor of astronomy at the 91̽��who leads the Alert Production Pipeline Group for the Rubin Observatory. “Rubin will survey the sky at an unprecedented scale and allow us to find the most rare and unusual objects in the universe. We can’t wait to see the exciting science that comes from these data.”

The beginning of scientific alerts is one of the last major milestones before Rubin Observatory launches its (LSST) later this year. During the LSST, Rubin will scan the Southern Hemisphere sky nightly for 10 years to precisely capture every visible change using . These alerts will chronicle the treasure trove of scientific discoveries that Rubin will make through its time-lapse record of the universe. In the first year of the LSST, Rubin is expected to capture images of more objects than all other optical observatories combined in human history.

The 91̽��played a central role in the software that enabled this month’s milestone. The alert pipeline was developed by a team of about two dozen researchers and software developers in the astronomy department’s . The team has spent the past decade working with other data management teams around the country to figure out how to process the staggering 10 terabytes of images that Rubin produces every night, and will continue to develop and operate the alert system throughout the 10-year LSST survey.

“Enabling real-time discovery on such a massive data stream has required years of technical innovation in image processing algorithms, databases and data orchestration. We’re thrilled to continue the UW’s legacy of excellence in data-driven science.” Bellm said.

While the night sky seems calm and unchanging to the casual viewer, it’s actually alive with motion and transformation. Each alert signals something that has changed in the sky since Rubin last looked — a new source of light, a star that brightened or dimmed, or an object that moved. With Rubin’s alerts, scientists will have a greater ability to catch supernovae in their earliest moments, discover and track asteroids to assess potential threats to Earth and spot rare interstellar objects as they race through the solar system.

Scientists can use these data to better understand the nature of dark matter, dark energy and other unknown aspects of the universe.

“The discoveries reported in these alerts reflect the power of NSF-DOE Rubin Observatory as a tool for astrophysics and the importance of sustained federal support,” said Kathy Turner, program manager in the High Energy Physics program in the U.S. Department of Energy’s . “Rubin Observatory’s groundbreaking capabilities are revealing untold astrophysical treasures and expanding scientists’ access to the ever-changing cosmos.”

Every 40 seconds during nighttime observations, Rubin captures a new region of the sky. It then sends the data on a seconds-long journey from Chile to the U.S. Data Facility (USDF) at the in California for initial processing. Rubin’s data management system automatically compares it to a template made from previous images of the same region. This comparison allows it to detect the slightest variations. With every change, such as the appearance of a new point of light, an object’s movement or a change in brightness, the system generates a public alert within two minutes.

“The scale and speed of the alerts are unprecedented,” says Hsin-Fang Chiang, a SLAC software developer leading operations for data processing at the USDF. “After generating hundreds of thousands of test alerts in the last few months, we are now able to say, within minutes, with each image, ‘Here is everything. Go.’”

Rubin’s alerts are public, meaning anyone — from professional researchers to students and citizen scientists — can access and explore them. The speed of the alerts allows scientists using other ground- and space-based telescopes around the world to coordinate follow-up observations. This collaboration will enable fast and detailed studies of unfolding phenomena.��

Additionally, through collaborations with platforms like , Rubin will empower the global community to help classify cosmic events and contribute directly to discovery.

Rubin Observatory is jointly operated by NSF and SLAC.

For more information, contact Bellm at ecbellm@uw.edu.

This story was adapted from a press release by and .

Operations of the Vera C. Rubin Observatory are funded by the U.S. National Science Foundation and the U.S. Department of Energy’s Office of Science.

A new era of astronomy and astrophysics began Monday when the first images captured by the NSF–DOE were released, demonstrating the extraordinary capabilities of the new telescope and the world’s largest digital camera.

Officials in Washington, D.C., unveiled large, ultra-high-definition images and videos, as well as discoveries of thousands of new asteroids. Astronomers and researchers around the world watched along at viewing parties, including at the 91̽��’s Planetarium.

The images offer a preview of the most comprehensive census of the solar system scientists have ever conducted, and a peek into the exponential increase in discoveries and understanding of the cosmos this new telescope will make possible.

The 91̽��was one of the founding members of Rubin’s ambitious undertaking and will play a key role in making sense of the discoveries. 91̽��scientists and engineers were critical in advocating for the project, designing the observatory and developing the software that will analyze the petabytes of data from Rubin’s telescope, including the asteroid discovery algorithms.

“91̽�� faculty recognized early on that dreaming big about Rubin’s capabilities and leading the scientific charge would shape our knowledge of the solar system and propel innovation in data science not only in astrophysics but also across disciplines,” said 91̽��Provost Tricia R. Serio. “We often talk about the impact the 91̽��is making here and around the world. This project will take us far into space and give us information about the very origins of the universe and set the stage for future discoveries we can’t even imagine today.”

From its peak in the Chilean Andes, Rubin’s Simonyi Survey Telescope will scan the sky with its 8.4-meter mirror and enormous 3,200-megapixel camera, the largest digital camera in the world. The telescope’s sight path, the pace and frequency of observations and the vast field of vision required a new type of discovery algorithm to reliably make sense of the troves of data collected. Scientists and researchers at the 91̽��worked across disciplines to evolve data science and computer science to meet Rubin’s demands.

In 2017, the 91̽��— with founding support from the Charles and Lisa Simonyi Fund for Arts and Sciences — established the , or DiRAC. The Institute, part of the , aims to be an interdisciplinary hub to address fundamental questions about the origins and evolution of the universe. Leaders recognized that the future of astrophysics relied on using software as the chief instrument for this exploration. Combined with the UW’s and the deep connections to the Pacific Northwest’s tech community, DiRAC has developed a global reputation for working toward new discoveries.

As the Rubin sets out on a 10-year mission to conduct the Legacy Survey of Space and Time (LSST), software created at the 91̽��will be pivotal as scientists advance understanding of the cosmos and the origins of the solar system. UW’s faculty, students and staff have played key roles in the construction of this new facility They’ve also been pivotal in developing the algorithms that keep the telescope image sharp and creating the codes for mapping the solar system and discovering the most energetic and rarest phenomena in what astrophysicists call the ” UW’s , a professor of astronomy, is the director of the federally-funded Rubin Construction Project.��

Unlike other telescopes — which tend to focus and “zoom in” on a few objects of interest — Rubin is alone in the capability to quickly and repeatedly map the entire visible sky.��

“Rubin has the unprecedented capacity to capture the cosmos,” said , a professor of astronomy and director of UW’s . He’s also the co-principal investigator of the supported LSST Interdisciplinary Network for Collaboration and Computing (LINCC) Frameworks program to develop state-of-the-art analysis techniques capable of meeting Rubin’s scale and complexity.

“Rubin will deliver the largest map the universe ever made: tens of billions of galaxies, billions of stars and millions of new small bodies in our own solar system. It’s a data analysis endeavor of epic proportions,” Connolly said.��

For each object Rubin observes, there will be much more than a static image, the technology will produce a thousand-frame movie: trillions of measurements of billions of objects, said , a research associate professor and the science lead of Rubin’s time-domain software team.

“With these data, scientists will better understand the universe, chronicle its evolution, and delve into science ranging from dangerous asteroids to the mysteries of dark energy,” Bellm said.

For example, the UW’s team helped create simulation software to predict Rubin’s discoveries. The research found that the telescope will map more than 5 million main-belt asteroids, 127,000 near-Earth objects, 109,000 Trojan asteroids that share Jupiter’s orbit, 37,000 trans-Neptunian objects and about 2,000 Centaurs, or orbit-crossing objects.��

These objects, revealed in color and in more detail than was previously possible, help tell the story of the solar system’s origins, said , a professor of astronomy and the principal investigator of UW’s Rubin team.

Juric said that Rubin will help answer some fundamental questions: How did the planets form? Is there an unknown planet hiding in the outskirts of our solar system? Did comets bring water to the Earth? Or asteroids? And are there any that could still collide with us today?

“The first look we share today is a glimpse into the transformational capacity Rubin will bring to answer questions like these,” Juric said.

The work to support the Rubin Observatory hasn’t been limited to 91̽��faculty. Numerous 91̽��undergraduate and doctoral students have played contributing roles, authoring important journal articles, developing simulation software and writing complex computer codes.��

Exposure to the LSST has helped prepare students to succeed post graduation, whether applying for work in industry or moving onto advanced academic degrees.

“Developing cloud-based analytics platforms, or building pipelines to process large amounts of imaging data, are skills that allow one to do not just cutting-edge astronomy but also any other data-intensive problem,” said Steven Stetzler, who recently completed doctoral work at 91̽��and now holds a postdoctoral appointment at NASA’s Jet Propulsion Laboratory.

For more information, contact Juric at mjuric@uw.edu or James Davenport at jrad@uw.edu.��

Since 2018 the , an international astronomical collaboration based at the Palomar Observatory in California, has scanned the entire sky every two to three nights. As part of this mission, the ZTF’s has been counting and cataloguing supernovae — flashes of light in the sky that are the telltale signs of stars dying in spectacular explosions.

On Dec. 4, ZTF researchers — including astronomers at the 91̽�� — announced that that they have identified more than 10,000 of these stellar events, the largest number ever identified by an astronomical survey.

“There are trillions of stars in the universe, and about every second, one of them explodes,” said Christoffer Fremling, an astronomer at Caltech who leads the Bright Transient Survey. “ZTF detects hundreds of these explosions per night and a handful are then confirmed as supernovae. Systematically doing this for seven years has led to the most complete record of confirmed supernovae to date.”

The Bright Transient Survey is currently the primary discovery pipeline for cosmic flashes — also known as astronomical transients — in the world. To determine which transients are supernovae, ZTF shares a stream of nightly transient detections with the wider astronomical community so that other telescopes around the world can conduct follow-up observations of candidate transients. This includes conducting a spectral analysis, in which instruments on observatory telescopes split the light from a transient object into its individual colors to reveal its distance from Earth and other properties.

“Classifying 10,000 supernovae is a tremendous achievement and will enable unprecedented scientific studies of explosive transients,” said ZTF team member , a 91̽��research associate professor of astronomy and scientist with the UW’s . “Reaching this milestone required careful technical work on scheduling and processing the ZTF discovery images, human and machine vetting of the alerts and obtaining timely follow-up spectra.”

For the Bright Transient Survey, a 60-megapixel wide-field camera mounted on Palomar’s Samuel Oschin telescope scanned the entire visible sky every two nights. To detect new astronomical events, astronomers subtracted images of the same portion of the sky from subsequent scans. Next, members of the ZTF team studied the subtracted images and triggered follow-up spectral observations by a second telescope at Palomar or other observatories.

Bellm, 91̽��research scientist and , 91̽��professor of astronomy and director of the DiRAC Institute, all contributed to the Bright Transient Survey. Bellm managed alerts of new transients and scheduled imaging for the survey. Jurić helped set up the ZTF’s automated system to alert team members around the world of new transients.

Developing automated analysis pipelines and alert systems are critical for the field as more powerful imaging technologies and new generations of observatories continue to transform astronomy into a “big data” endeavor. , a 20th century astronomer who first coined the term “supernova,” identified 120 supernovae in 52 years. The Bright Transient Survey by the ZTF — named for Zwicky — found 10,000 in a fraction of that time.

“The Bright Transient Survey program serves as an exemplar for the kinds of science we hope to do with the in the near future,” said Bellm.

Under construction in Chile, the Vera C. Rubin Observatory is the future home of the Legacy Survey of Space and Time, or LSST, a mission that will take deep images of the sky nightly and detect even more cosmic transients than ZTF. 91̽��scientists with the DiRAC Institute have been heavily involved in planning for the launch of the LSST. Collaborations like the ZTF have been a proving ground for developing and testing methods for use in the LSST.

For the Bright Transient Survey, Graham conducted follow-up spectral analyses of transients at in New Mexico. These efforts were especially valuable in catching some of the fainter, fading supernovae that would have been missed at Palomar.

“As 91̽��astronomers, we are so fortunate to have access to the Apache Point Observatory for our research,” said Graham. “One of the most impactful — and fun — parts of obtaining optical spectra is being surprised by rare transients with peculiar characteristics, which often reveal more about supernova physics than hundreds of ordinary objects. Figuring out how to do this work with the even larger number of LSST supernovae is the next big challenge.”

Most of the transients in the Bright Transient Survey are classified as one of two common types of supernovae: Type Ia, when a white dwarf steals so much material from another nearby star that it explodes, or Type II, when massive stars collapse and die under their own gravity. Thanks to the treasure trove of data from the Bright Transient Survey, astronomers are now better equipped to answer questions about how stars grow and die, as well as how dark energy drives the expansion of the universe.

After its expected 2025 commissioning, the Vera Rubin C. Observatory could discover millions more supernovae.

“The machine learning and AI tools we have developed for ZTF will become essential when the Vera Rubin Observatory begins operations,” said ZTF team member Daniel Perley, an astronomer at Liverpool John Moores University. “We have already planned to work closely with Rubin to transfer our machine learning knowledge and technology.”

With an additional $1.6 million of funding from the National Science Foundation, ZTF will continue to scan the night sky for the next two years.

“The period in 2025 and 2026 when ZTF and Vera Rubin can both operate in tandem is fantastic news for time-domain astronomers,” said Mansi Kasliwal, an astronomy professor at Caltech who will lead ZTF in the next two years. “Combining data from both observatories, astronomers can directly address the physics of why supernovae explode and discover fast and young transients that are inaccessible to ZTF or Rubin alone. I am excited about the future.”

For more information, contact Bellm at ecbellm@uw.edu and Graham at mlg3k@uw.edu.

Adapted from a by Caltech.

The flashing of a nearby star drew the attention of a team of astronomers, who discovered that it is part of a rare and mysterious system. As they report in a published May 4 in Nature, the stellar oddity appears to be a “black widow binary” — a type of system consisting of a rapidly spinning neutron star, or pulsar, that is circling and slowly consuming a smaller companion star, as its arachnid namesake does to its mate.

The team, led by co-author , a postdoctoral researcher at the Massachusetts Institute of Technology, found the black widow binary utilizing data from the , a California-based observatory that takes wide-field images of the night sky.

“This discovery highlights the potential of large time-domain surveys like ZTF to find rare astrophysical objects,” said co-author , a research assistant professor of astronomy at the 91̽��, fellow at the UW’s and scientist with both the ZTF and the Chile-based Vera C. Rubin Observatory.

Astronomers know of about two dozen black widow binaries in the Milky Way. This newest candidate, named ZTF J1406+1222, lies 3,000 light-years from Earth and has the shortest orbital period yet identified, with the pulsar and companion star circling each other every 62 minutes. The system is unique in that it also appears to host a third far-flung star that orbits the two inner stars every 10,000 years.

This “triple” black widow raises questions about how such a system could have formed. Based on its observations, the team proposed an origin story: As with most black widow binaries, the triple system likely arose from a dense constellation of old stars known as a globular cluster. This particular cluster may have drifted into the Milky Way’s center, where the gravity of the central black hole puled the cluster apart while leaving the triple black widow intact.

“It’s a complicated birth scenario,” said Burdge. “This system has probably been floating around in the Milky Way for longer than the sun has been around.”

Pulsars, which are the collapsed cores of massive stars, have a dizzying rotational period, spinning around every few milliseconds, and emitting flashes of high-energy gamma and X-rays in the process.

Normally, pulsars spin down and die quickly as they burn off a huge amount of energy. But occasionally, the pulsar’s gravity can pull material off of a passing wayward star, providing new energy to spin the pulsar back up. The “recycled” pulsar then starts reradiating energy that further strips the star and eventually destroys it.

While most black widow binaries are found through the gamma and X-ray radiation emitted by the central pulsar, the team used visible light from the flashing from the binary’s companion star to detect ZTF J1406+1222. Burdge recognized that the companion star’s so-called “day” side — the side perpetually facing the pulsar — can be many times hotter than its “night” side, due to the constant high-energy radiation it receives from the pulsar. He reasoned that if astronomers observed a star whose brightness was changing periodically by a large amount, it would be a strong sign that it was in a binary with a pulsar.

To test this theory, Burdge and his co-authors studied the brightness of stars from ZTF data to see whether any were changing dramatically by a factor of 10 or more, and on a time scale of about an hour or less. The team was able to pick out the dozen known black widow binaries, validating the new method’s accuracy. They then spotted a star whose brightness changed by a factor of 13, every 62 minutes, indicating that it was likely part of a new black widow binary.

Looking back through decades-old measurements of the star​ by the Sloan Digital Sky Survey, they found evidence that the binary was being trailed by another distant star. By their calculations, this third star appeared to be orbiting the inner binary every 10,000 years.

Curiously, the astronomers have not directly detected gamma or X-ray emissions from the pulsar in the binary, which is the typical way that black widows are confirmed. As a result, for now ZTF J1406+1222 is considered a candidate black widow binary, which the team hopes to confirm with future observations.

“Everything seems to point to it being a black widow binary,” Burdge said. “But there are a few weird things about it, so it’s possible it’s something entirely new.”

The team plans to continue observing the new system, as well as apply the optical technique to illuminate more neutron stars and black widows in the sky.

“Identifying this black widow binary with ZTF alone suggests that we should be able to find even more such systems in a few years when the even more powerful Vera C. Rubin Observatory comes online,” said Bellm.

Co-authors include scientists at the University of Warwick; Caltech; McGill University; the University of Maryland, College Park; the University of Minnesota; the University of Sheffield; the University of Wisconsin–Milwaukee; National Cheng Kung University; National Tsing Hua University; Institute of Astrophysics of the Canary Islands; the University of La Laguna; Stockholm University; and the University of California, Berkeley. The research was funded by the National Science Foundation.

For more information, contact Bellm at ecbellm@uw.edu.

Adapted from a by MIT.

Less than a year into its mission, a sky-survey camera in Southern California shows just how full the sky is. The , based at the Palomar Observatory in San Diego County, has identified over a thousand new objects and phenomena in the night sky, including more than 1,100 new supernovae and 50 near-Earth asteroids, as well as binary star systems and black holes. Operated by Caltech, the ZTF is a public-private partnership between the National Science Foundation and a consortium of nine other institutions around the globe, including the 91̽��. The ZTF collaboration’s six latest papers, which describe these discoveries as well as the ZTF’s data mining, sorting and alert systems, have been accepted for publication in the journal .

, the ZTF survey scientist and a research assistant professor of astronomy at UW, is lead author on a paper describing the ZTF’s technical systems and major findings since the survey began on March 20, 2018. , a data scientist formerly with the 91̽��Department of Astronomy’s , is lead author on another paper describing the ZTF’s alert system for notifying science teams of possible new objects in the sky or significant changes to existing objects.

“The ZTF mission is to identify changes in the night sky and alert the astronomical field of these discoveries as quickly as possible,” said Bellm, who is also a fellow with the DIRAC Institute. “The results and specifications reported in these six papers demonstrate that the ZTF has in place a pipeline to identify new objects, as well as analyze and disseminate information about them quickly to the astronomy community.”

Science teams need quick alerts so that they could, if needed, arrange for follow-up observations of individual objects by other observatories, Bellm added.

The ZTF accomplishes its survey goals through a digital camera, consisting of 16 charge-coupled devices, mounted to the 48-inch-aperture at Palomar. A single image from the camera covers an area about 240 times the size of the moon; in just one night, the ZTF could image the entire night sky visible from the Northern Hemisphere. So far, the ZTF camera has imaged more than 1 billion stars in our galaxy alone. By comparing new images to old, the ZTF can identify objects that are new, such as a supernova lighting up for the first time, or changes to existing objects, such as a star brightening in luminosity.

The ZTF undertakes surveys for public agencies such as the National Science Foundation, as well as private entities. The sheer volume of data generated by the ZTF necessitated a new approach to data analysis and alerts, according to Bellm.

“Every image that the ZTF takes contributes to at least one survey,” said Bellm. “We needed to put an automated alert system in place that would inform the relevant survey teams – in near-real time – of every potential change or new object that the ZTF would uncover, which could be more than a million in a single night.”

Patterson, Bellm and other 91̽��scientists — including , associate professor of astronomy and senior data fellow with the — led the effort within the ZTF to craft the automated alert system. They utilized two open-source technologies: Kafka, a real-time data-streaming platform, and Avro, a framework to serialize data for transmission and storage. The completed alert system, which was first deployed in June 2018, has successfully generated and distributed up to 1.2 million ZTF alerts each night — with each alert going out to survey teams approximately 10 seconds after it was automatically generated.

“Through these alert systems, the ZTF is sharing every change it finds with our survey partners,” said Bellm. “They are receiving every bit of data.”

Survey partners, in turn, are experimenting with machine-learning classification systems and other analysis tools to sort through the alerts.

The ZTF’s alert system is a proving ground for future “automated, time-domain astronomy” missions such as the , said Bellm. The LSST, which is expected to begin its sky surveys in 2022, should generate about 10 million alerts per night, which is about 10 times the maximum alert volume of the ZTF. But the ZTF alert system could form the basis of a scaled-up alert pipeline for the LSST, according to Bellm.

“We are very pleased with the opportunities that the ZTF mission has provided us,” said Bellm. “It is reassuring to know that we have the tools at hand today that are useful not only for ongoing surveys at the ZTF, but also future missions like the LSST.”

The ZTF is funded by the NSF, Heising-Simons Foundation and the ZTF member institutions: Caltech, the 91̽��, the Weizmann Institute of Science, the Oskar Klein Centre at Stockholm University, the University of Maryland, the Deutsches Elektronen-Synchrotron, Humboldt University of Berlin, the TANGO Consortium of Taiwan, the University of Wisconsin-Milwaukee and the Lawrence Berkeley National Laboratory.

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For more information, contact Bellm at ecbellm@uw.edu.

ZTF papers accepted for publication:

• “” by Eric Bellm (91̽��) et al.
• “The Zwicky Transient Facility: Science Objectives” by Matthew Graham (Caltech) et al.
• “” by Frank Masci (Caltech) et al.
• “Machine Learning for the ZTF” by Ashish Mahabal (Caltech) et al.
• “” by Maria Patterson (91̽��) et al.
• “The GROWTH Marshal: A Dynamic Science Portal for Time-domain Astronomy” by Mansi Kasliwal (Caltech) et al.

The first astronomers had a limited toolkit: their eyes. They could only observe those stars, planets and celestial events bright enough to pick up unassisted. But today’s astronomers use increasingly sensitive and sophisticated instruments to view and track a bevy of cosmic wonders, including objects and events that were too dim or distant for their sky-gazing forebears.

On Nov. 14, scientists with the California Institute of Technology, the 91̽�� and eight additional partner institutions, that the , the latest sensitive tool for astrophysical observations in the Northern Hemisphere, has seen “” and took its first detailed image of the night sky.

When fully operational in 2018, the ZTF will scan almost the entire northern sky every night. Based at the Palomar Observatory in southern California and operated by Caltech, the ZTF’s goal is to use these nightly images to identify “transient” objects that vary between observations — identifying events ranging from supernovae millions of light years away to near-Earth asteroids.

In 2016, the 91̽��Department of Astronomy formally joined the ZTF team and will help develop new methods to identify the most “interesting” of the millions of changes in the sky — including new objects — that the ZTF will detect each night and alert scientists. That way, these high-priority transient objects can be followed up in detail by larger telescopes, including the UW’s share of the 3.5-meter telescope.

“ 91̽��is a world leader in survey astronomy, and joining the ZTF will deepen our ability to perform cutting-edge science on the ZTF’s massive, real-time data stream,” said , a 91̽��assistant professor of astronomy and the ZTF’s survey scientist. “One of the strengths of the ZTF is its global collaboration, consisting of experts in the field of time-domain astronomy from institutions around the world.”

Identifying, cataloguing and classifying these celestial objects will impact studies of stars, our solar system and the evolution of our universe. The ZTF could also help detect electromagnetic counterparts to gravitational wave sources discovered by Advanced LIGO and Virgo, as other observatories did in August when these detectors picked up gravitational waves from .

But to unlock this promise, the ZTF requires massive data collection and real-time analysis — and 91̽��astronomers have a history of meeting such “big data” challenges.

The roots of big data astronomy at the 91̽��stretch back to the , which used a telescope at the Apache Point Observatory in New Mexico to gather precise data on the “redshift” — or increasing wavelength — of galaxies as they move away from each other in the expanding universe.�� Once properly analyzed, the data helped astronomers create a more accurate 3-D “map” of the observable universe. The UW’s survey astronomy group is gathered within the , which includes scientists in the Department of Astronomy as well as the eScience Institute and the Paul G. Allen School of Computer Science & Engineering.

“It was natural for the 91̽��astronomy department to join the ZTF team, because we have assembled a dedicated team and expertise for ‘big data’ astronomy, and we have much to learn from ZTF’s partnerships and potential discoveries,” said 91̽��associate professor of astronomy .

From Earth, the sky is essentially a giant sphere surrounding our planet. That whole sphere has an area of more than 40,000 square degrees. The ZTF utilizes a new high-resolution camera mounted on the Palomar Observatory’s existing Samuel Oschin 48-inch Schmidt Telescope. Together these instruments make up the duet that saw first light recently, and after months of fine-tuning they will be able to capture images of 3,750 square degrees each hour.

These images will be an order of magnitude more numerous than those produced by the ZTF’s predecessor survey at Palomar. But since these transient objects might fade or change position in the sky, analysis tools must run in near real time as images come in.

“We’ll be looking for anything subtle that changes over time,” said Bellm. “And given how much of the sky ZTF will image each night, that could be tens of thousands of objects of potential interest identified every few days.”

From a data analysis standpoint, these are no easy tasks. But, they’re precisely the sorts of tasks that 91̽��astronomers have been working on in preparation for the Large Synoptic Survey Telescope, which is expected to see first light in the next decade. The LSST, located in northern Chile, is another big data project in astrophysics, and is expected to capture images of almost the entire night sky every few days.

“Data from the ZTF surveys will impact nearly all fields of astrophysics, as well as prepare us for the LSST down the line,” said Juric.

The ZTF is funded by the National Science Foundation and its partner institutions. The UW’s participation with the ZTF was made possible by funds provided by the College of Arts & Science, the DIRAC Institute and the Washington Research Foundation. The DIRAC Institute is funded in part by the Charles and Lisa Simonyi Fund for Arts and Sciences.

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For more information, contact Bellm at ecbellm@uw.edu and Juric at mjuric@astro.washington.edu.