Super-wide-angle Zwicky Transient Facility celebrates ‘first light’ with help from UW
ZTF first light
The Zwicky Transient Facility captured this “first light” image on Nov. 1. The Orion Nebula is at lower right. Computers searching these images for quick-changing events are trained to recognize and ignore non-astronomical artifacts such as the vertical lines seen here. (Caltech Optical Observatories)

A sky survey that draws upon the data-crunching skills of researchers at the University of Washington has reached a milestone known as “first light” — and the view is awesome.

The Zwicky Transient Facility takes super-wide-angle pictures of the night sky, using a robotic camera hooked up to the 48-inch Samuel Oschin Telescope at Caltech’s Palomar Observatory in the mountains near San Diego.

“First light” occurs when astronomers capture their first image with a new observing instrument. ZTF’s first-light image, taken on Nov. 1, shows a wide swath of the sky that includes the Orion Nebula.

Each ZTF exposure covers a sky area equal to 247 full moons, or 47 square degrees, resulting in an image that’s bigger than 24,000 by 24,000 pixels at full resolution. The camera can cover the entire northern sky in the course of three nights, and scan the visible plane of the Milky Way twice each night.

The aim of the ZTF project is to catch transient sky phenomena that appear and fade quickly, ranging from supernovas, to asteroids and comets, to the outbursts associated with neutron star collisions and gravitational-wave emissions.

“There’s a lot of activity happening in our night skies,” Caltech’s Shri Kulkarni, principal investigator for the ZTF campaign, explained in a news release. “In fact, every second, somewhere in the universe, there’s a supernova that’s exploding. Of course, we can’t see them all, but with ZTF we will see up to tens of thousands of explosive transients every year over the three-year lifetime of the project.”

ZTF’s data archive is expected to grow by 4 trillion bytes each night.

Half of the funding for the project, which is named after the late Caltech astronomer Fritz Zwicky, comes from the National Science Foundation. The other half comes from academic partners, including the University of Washington.

One of UW’s primary roles is to develop software used for automated processing of ZTF imagery., under the auspices of its DIRAC Institute. (DIRAC stands for “Data Intensive Research in Astrophysics and Cosmology.”)

The researchers at DIRAC are building the real-time alert distribution system and filtering service that spreads the word about ZTF discoveries for follow-up observations. They’re also exploring new approaches to handling large databases of time-dependent observations to identify rare and exotic astronomical objects.

ZTF will blaze a trail for even bigger sky surveys that will be done using the Large Synoptic Survey Telescope in Chile. It’s expected to achieve first light for engineering purposes in 2019, science first light in 2021, and full-scale science operations by 2023.

“The upcoming LSST will be 10 times faster than ZTF,” Kulkarni said. And that means the software tools developed by DIRAC will have to be faster and smarter as well.

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